By Dr. Inge Heinzl, Editor, EW Nutrition

In piglet production, high productivity, meaning high numbers of healthy and well-performing piglets weaned per sow and year, is the primary target. Diarrhea around weaning often gets in the way of achieving this goal.

Up to the ban of antibiotic growth promoters in 2006, antibiotics were often applied prophylactically to help piglets overcome this critical time. Zinc oxide (ZnO) application is another measure that cannot be used anymore to prevent piglet diarrhea. Effective alternatives are required.

Weaning – a critical point in piglets’ life

Weaning stress is well-known to have a negative impact on the balance of the intestinal microflora and gastrointestinal functions (Miller et al., 1985). Suckling piglets have a limited ability to produce hydrochloric acid, but nature has a solution to compensate for this inadequacy. The lactobacilli present in the stomach can use the lactose in the sow’s milk to produce lactic acid (Easter, 1988). In nature, the piglets would start to eat small amounts of solid feed at about three weeks when the sow’s milk production no longer covers their nutrient demand. By increasing the feed intake, the piglets stimulate hydrogen chloride (HCl) production in their stomachs.

In piglet production, where weaning occurs at three or four weeks of age, the piglets are still not eating considerable amounts of solid feed. It is often the case that 50 % of the piglets take feed at the earliest after 24 h, and 10 % accept the first feed only after 48 h (Brooks, 2001). Additionally, hard grains in the diet can physically damage the small intestine wall, reducing villus height and crypt depth (Kim et al., 2005).

Only a minor production of HCl, no more lactose supply for the lactobacilli, varying feed intake, and high buffering capacity of the feed lead to a pH of >5 in the stomach.

The higher stomach pH is partly responsible for problems after weaning

A pH higher than 5, besides causing direct effects on the microflora in the stomach, has consequences for the whole digestive tract and digestion.

A high pH is favorable for certain microorganisms, including coliforms (Sissons, 1989) and other acid-sensitive bacteria such as Salmonella typhimurium, Salmonella typhi, Campylobacter jejuni, and V. cholerae (Smith, 2003).

1.  Lower activity of proteolytic enzymes

   In the stomach, the conversion of pepsinogen to pepsin, which is responsible for protein digestion, is catalyzed under acid conditions (Sanny et al., 1975). Pepsin works optimally at two pH levels: pH 2 and pH 3.5 (Taylor, 1959). With increasing pH, the activity decreases; at pH 6, it stops. Therefore, a high pH can lead to poor digestion and undigested protein arriving in the intestine. There, it can be used as “feed” for harmful bacteria, leading to their proliferation. Barrow et al. (1977) found higher counts of coliforms in piglets’ intestinal tract two days after weaning, while the number of lactobacilli was depressed.

   In the lower parts of the gastrointestinal tract (GIT), the final products of the pepsin protein digestion are needed to stimulate the secretion of pancreatic proteolytic enzymes. If no final products arrive, the enzymes are not activated, and the inadequate protein digestion continues. Additionally, gastric acid is the main stimulant for bicarbonate secretion in the pancreas, neutralizing gastric acid and providing an optimal pH environment for the digestive enzymes working in the duodenum.

2. Expedited digesta transport

   The stomach pH also influences the transport of digesta. The acidity of the chyme leaving the stomach and arriving in the small intestine is decisive for the amount of digesta being transferred from the stomach to the small intestine. Acid-sensitive receptors provide feedback regulation to prevent the stomach from emptying until the duodenal chyme can be neutralized by pancreatic or other secretions (Pohl et al., 2008). Therefore, a higher pH in the stomach leads to a faster transport of the digesta, resulting in worse feed digestion.

3. Proliferation of microorganisms

   A high pH is favorable for certain microorganisms, including coliforms (Sissons, 1989) and other acid-sensitive bacteria such as Salmonella typhimurium, Salmonella typhi, Campylobacter jejuni, and V. cholerae (Smith, 2003).

   Elevated stomach pH + incomplete immune system = diarrhea

Acidifiers can mitigate the adverse effects of weaning on piglets

To overcome this critical time of weaning and maintain performance, acidifiers can be a helpful tool. They improve gut health, stimulate immunity, and serve as nutrient sources – while also positively affecting feed and water hygiene.

What are acidifiers?

Acidifiers’ role in pig nutrition has evolved from feed preservatives to stomach pH stabilizers, compensating for young pigs’ reduced digestive capacity (Ferronato and Prandini, 2020). They are now used to replace antibiotic growth promoters and ZnO, which were applied for a long time to mitigate the negative effects of weaning.

In general, both organic and inorganic acids and their salts feature in animal nutrition. They can be added to the feed or the water.

Organic acids: Commonly used with good results

Feed acidifiers are usually organic acids, including fatty and amino acids. Their carboxyl functional group is responsible for their acidic specificity as feed additives (Pearlin et al.,2019). Their pKa, the pH where 50 % of the acid occurs in a dissociated form, is decisive for their antimicrobial action. In animal nutrition, acids with pKa 3-5 are typically used (Kirchgeßner and Roth, 1991).

Organic acids used as feed additives can be divided into three groups:

•  Simple monocarboxylic acids such as formic, acetic, propionic, and butyric acid
•  Carboxylic acids with a hydroxyl group such as lactic, malic, tartaric, and citric acid
• Short-chain carboxylic acids with double bonds – fumaric and sorbic acid.

The primary acids for pig nutrition are acetic, fumaric, formic, lactic, benzoic, propionic, sorbic, and citric acids (Roth and Ettle, 2005).

Inorganic acids – the low-cost version

Inorganic acids are cheaper than organic acids, but their only effect is to decrease the pH. Additionally, they are extremely corrosive and dangerous liquids due to their strong acidity in a pure state (Kim et al., 2005).

Salts are easier to handle

The advantage of salts over free acids is that they are generally odorless and easier to handle in the feed manufacturing process due to their solid and less volatile form. Higher solubility in water is a further advantage compared to free acids (Huyghebaert and Van Immerseel, 2011; Roth and Ettle, 2005; Partanen and Mroz, 1999). The better handling and higher palatability make acid salts a more user-friendly method to apply acids to feed and water without compromising their efficacy (Luise et al., 2020).

The salts are mainly produced with calcium, potassium, and sodium. They include calcium formate, potassium diformate, sodium diformate, and sodium fumarate.

Blends

A mixture of diverse acidifiers combines the different characteristics of these substances. Perhaps, there may be synergistic effects. Acid blends are more and more used as feed additives. They have a wider-ranging action than single substances.

Roth et al. (1996) showed that a combination of formic acid with various formats is more effective than the application of formic acid alone.

The main effects of acidifiers

Acidifiers support piglets during the critical time after weaning through different modes of action. The final results are:

• Improvement in gut health
• Increase in growth performance
• Stabilization of the immune system.

1.    Improvement in gut health

As shown in figure 1, the improvement in gut health relies on the antimicrobial effect of organic acids and the decrease in the stomach’s pH.

1.1     Organic acids directly attack bacteria

Organic acids not only act through their pH-decreasing effect but also directly attack pathogens. Due to their lipophilic character, organic acids can pass the bacterial cell membrane when they are in their undissociated form (Partanen in Piva et al., 2001). The lower the external pH, the more undissociated acid can pass the membrane.

Within the cell, the pH is higher. Hence, the organic acid dissociates and releases hydrogen ions, reducing the cytoplasmic pH from alkaline to acid. Cell metabolism is depressed at lower pH. Therefore, the bacterial cell needs to expel protons to get the cytoplasmic pH back to normal. As this is an energy-consuming process, more prolonged exposure to organic acids kills the bacterium. Additionally, the anions staying within the cell disturb the cell’s metabolic processes and participate in killing the bacterium.

Studies from Van Immerseel et al. (2006) revealed that many fermentative bacteria could let their intracellular pH decline and prevent increased acid penetration. Bacteria with a neutrophil pH, however, react more sensitively.

1.1     Decreased pH reduces non-acid-tolerant pathogens

There is a direct effect of pH on the microflora. Some pathogenic bacteria are susceptible to low pH. The proliferation of, e.g., E. coli, Salmonella, and Clostridium perfringens is minimized at a pH<5. Acid-tolerant bacteria such as lactobacilli or bifidobacteria, however, survive. Many lactobacilli can produce hydrogen peroxide, which inhibits, e.g., Staphylococcus aureus or Pseudomonas spp. (Juven and Pierson, 1996).

Already Fuller (1977) showed in in vitro experiments that certain bacteria such as Streptococci, Salmonella, and B. cereus don’t grow in an environment with pH 4.5 or even die (Micrococcus). In contrast, Lactobacilli are not so susceptible to this low pH. Using the same binding sites as harmful bacteria, they suppress coliforms, for example. Kirchgeßner et al. (1997) found a stronger reduction of E. coli than Lactobacilli and Bifidobacteria in different gut segments when exposed to 1.25 % formic acid.

1.2     Recovery of eubiosis through reduction of substrate

The reduction of the pH through organic acids maintains or stimulates the secretion of proteolytic enzymes in the stomach (pepsin) and pancreatic enzymes. Additionally, the acid leaving the stomach is partly responsible for regulating gastric emptying (Ravindran and Kornegay, 1993; Mayer, 1994). Both effects by improving protein digestion, reduce the fermentable substrates arriving in the hindgut. This decreases the quantity of fermentable substrate arriving in the intestine and, therefore, the growth of undesired pathogens.

2. Promotion of growth

2.1     Enhanced digestion of macronutrients

As explained above, the acidity in the stomach is responsible for the activation and stimulation of enzymes. Additionally, the lower pH keeps the feed in the stomach for longer. Both result in better digestion.

The improved utilization of nutrients leads to higher daily gain and better feed conversion. In pigs, the growth-promoting effect of organic acids is particularly pronounced during the first few weeks after weaning (Roth and Ettle, 2005). Some examples of the growth-promoting effect of formic and propionic acid feature in table 1.

Table 1: Influence of two commonly used organic acids in animals on growth performance

Varying results are mainly due to the character of the organic acid, the dosage, the buffering capacity, and the possible reduction of feed intake in case of a high dosage (Roth and Ettle, 2005).

2.2     Improved utilization of minerals

Minerals are essential for metabolic processes and, thus, healthy growth. Chelated minerals show a higher digestibility. Acidic anions of the acidifiers form complexes (chelates) with cationic minerals such as Ca, Zn, P, and Mg. The resulting higher digestibility and absorption lead to decreased excretion of supplemented minerals and, therefore, to a lower environmental burden. Kirchgeßner and Roth (1982), e.g., reported an improved absorption and retention of Ca, P, and Zn with the addition of fumaric acid. However, there are also trials showing no effect of acidification of the diet on mineral balance (Radecki et al., 1988).

Phytic acid

Another factor influencing the absorption of minerals, mainly phosphorus, is the amount of intrinsic or microbial phytase in the diet (Rutherfurd et al., 2012). The enzyme phytase releases phosphorus out of phytic acid and increases its bioavailability. Partanen and Mroz (1999) showed that organic acids improve the performance of phytase and, therefore, the bioavailability of phosphorus in the diet.

Besides a better utilization by the animal, improved absorption of minerals means preserving the environment and direct cost-saving, as mineral supplements are expensive.

2.3     Stimulation of gut and stomach mucosal morphology

An intact gut mucosa with a preferably high surface is vital for efficient nutrient absorption. Many trials show that organic acids improve the condition of the mucosa:

Organic acids stimulate cell proliferation

In an in vitro trial with pig hindgut mucosa, butyric acid stimulated epithelial cell proliferation in a dose-dependent manner (Sakata et al., 1995).

Blank et al. reported that fumaric acid, being a readily available energy source, may have a local trophic effect on the small intestines’ mucosa. Due to faster recovery of the gastrointestinal epithelial cells after weaning, this trophic effect may increase the absorptive surface and digestive capacity in the small intestines.

Organic acids influence villi length and crypt depth in the gut

Ferrara et al. (2016) observed a trend toward longer villi with a mixture of short-chain organic acids and mid-chain fatty acids, compared to the negative control.

The addition of Na-butyrate to the feed leads to increased crypt depth, villi length, and mucosa thickness in the distal jejunum and ileum, according to Kotunia et al. (2004). However, the villi length and mucosa thickness were reduced in the duodenum.

According to Gálfi and Bokori (1990), a diet with 0.17% sodium butyrate increased the length of ileal microvilli and the depth of caecal crypts in pigs weighing between 7 and 102 kg.

Organic acids strengthen stomach mucosa

Mazzoni et al. (2008) reported that sodium butyrate applied orally at a low dose influenced gastric morphology and function (thickening the mucosa), presumably due to its action on mucosal maturation and differentiation.

2.4    Pigs can use organic acids acid as an energy source

Organic acids are usually added to the feed in small doses. As some organic acids are intermediary products of the citric acid cycle, they are an energy source after being absorbed through the gut epithelium by passive diffusion. Their gross energy can be fully metabolized (Pearlin et al., 2019; Roth and Ettle, 2005; Suiryanrayna and Ramana, 2015).

The gross energy supply varies according to the acid. Roth and Ettle (2005) determined values between 6 kJ/g (formic acid) and 27 kJ/g (sorbic acid). Pearlin et al. (2019) calculated that 1 M of fumaric acid generates 1.340 kJ or 18 M ATP; this is comparable to the energy provision of glucose. Citric acid’s energy provision is similar; acetic and propionic acid require 18 and 15 % more energy to generate 1 M ATP.

Acidifiers improve immune response

The immune system, especially at the sensitive life stage of weaning, plays an essential role for the piglet. Acidifiers have been shown to stimulate or support the immune system. Ahmed et al. (2014) showed that citric acid (0.5 %) and a blend of acidifiers composed of formic, propionic, lactic, phosphoric acid + SO2(0.4 %) significantly increased the level of serum IgG. IgG are part of the humoral immune system. They mark foreign substances to be eliminated by other defense systems.

In a trial conducted by Ren et al. (2019), piglets receiving a mixture of formic and propionic acid showed lower concentrations of plasma tumor necrosis factor-α, regulating the activity of diverse immune cells. Furthermore, interferon-γ and interleukin (Il)-1ß were lower than in the control group after the challenge with E. coli (ETEC). In this trial, the addition of organic acids to the feed alleviated the inflammatory response in a way comparable to antibiotics.

In a nutshell

Organic acids are no longer seen as pure acidifiers but as growth promoters and potential antibiotic substitutes due to their positive effect on the gastrointestinal tract. Their main effect, the decrease of pH, entails consequences from inhibiting pathogenic bacteria and improved digestion to enhanced health and growth.
Research indicates that acidifiers can be a viable alternative to antibiotic growth promoters and ZnO for ensuring healthy piglet production after weaning.

By Marisabel Caballero, Global Technical Manager Poultry, EW Nutrition

Most grains used in feed are susceptible to mycotoxin contamination, causing severe economic losses all along feed value chains. As skyrocketing raw material prices force producers to include a higher proportion of economical cereal byproducts in the feed, the risks of mycotoxin contamination likely increase. In this article, we review why mycotoxins cause the damage they do – and how effective toxin-mitigating solutions prevent this damage.

Mycotoxin contamination of cereal byproducts requires solutions

Cereal byproducts may become more important feed ingredients as grain prices increase. But also from a sustainability point of view and considering population growth, using cereal byproducts in animal feed makes  a lot of sense. Dried distiller’s grains with solubles (DDGS) are a good example of how byproducts from food processing industries can become high-quality animal feed.

Figure 1: Byproducts are a crucial protein source (data from FEFAC Feed & Food 2021 report)

Still, research on what happens to mycotoxins during food processing shows that mycotoxins are concentrated into fractions that are commonly used as animal feed (cf. Pinotti et al., 2016 + link to article IH+MC ). To safeguard animal health and performance when feeding lower-quality cereals, it is essential to monitor mycotoxin risks through regular testing and to use toxin-mitigating solutions.

Problematic effects of mycotoxins on the intestinal epithelium

Most mycotoxins are absorbed in the proximal part of the gastrointestinal tract. This absorption can be high, as in the case of aflatoxins (ca. 90%), but also very limited, as in the case of fumonisins (< 1%); moreover, it depends on the species. Importantly, a significant portion of unabsorbed toxins remains within the lumen of the gastrointestinal tract.

Importantly, studies based on realistic mycotoxin challenges (e.g., Burel et al., 2013) show that the mycotoxin levels necessary to trigger damaging processes are lower than the levels reported as safe by EFSA, the Food Safety Agency of the European Union. The ultimate consequences range from diminished nutrient absorption to inflammatory responses and pathogenic disorders in the animal (Figure 2).

Figure 2: Mycotoxins’ impact on the GIT and consequences for monogastric animals

1.  Alteration of the intestinal barrier‘s morphology and functionality

   Several studies indicate that mycotoxins such as aflatoxin B1, DON, fumonisin B1, ochratoxin A, and T2, can increase the permeability of the intestinal epithelium of poultry and swine (e.g. Pinton & Oswald, 2014). This is mostly a consequence of the inhibition of protein synthesis.

   As a result, there is an increase in the passage of antigens into the bloodstream (e.g., bacteria, viruses, and toxins). This increases the animal’s susceptibility to infectious enteric diseases. Moreover, the damage that mycotoxins cause to the intestinal barrier entails that they are also being absorbed at a higher rate.

2. Impaired immune function in the intestine

   The intestine is a very active immune site, where several immuno-regulatory mechanisms simultaneously defend the body from harmful agents. Immune cells are affected by mycotoxins through the initiation of apoptosis, the inhibition or stimulation of cytokines, and the induction of oxidative stress.

   For poultry production, one of the most severe enteric problems of bacterial origin is necrotic enteritis, which is caused by Clostridium perfringens toxins. Any agent capable of disrupting the gastrointestinal epithelium – e.g. mycotoxins such as DON, T2, and ochratoxin – promotes the development of necrotic enteritis.

3. Alteration of the intestinal microflora

   Recent studies on the effect of various mycotoxins on the intestinal microbiota show that DON and other trichothecenes favor the colonization of coliform bacteria in pigs. DON and ochratoxin A also induce a greater invasion of Salmonella and their translocation to the bloodstream and vital organs in birds and pigs – even at non-cytotoxic concentrations.

   It is known that fumonisin B1 may induce changes in the balance of sphingolipids at the cellular level, including for gastrointestinal cells. This facilitates the adhesion of pathogenic bacteria, increases in their populations, and prolongs infections, as has been shown for the case of E. coli. The colonization of the intestine of food-producing animals by pathogenic strains of E. coli and Salmonella also poses a risk for human health.

4. Interaction with bacterial toxins

   When mycotoxins induce changes in the intestinal microbiota, this can lead to an increase in the endotoxin concentration in the intestinal lumen. Endotoxins promote the release of several cytokines that induce an enhanced immune response, causing inflammation, thus reducing feed consumption and animal performance, damage to vital organs, sepsis, and death of the animals in some cases.

   The synergy between mycotoxins and endotoxins can result in an overstimulation of the immune system. The interaction between endotoxins and estrogenic agents such as zearalenone, for example, generates chronic inflammation and autoimmune disorders because immune cells have estrogen receptors, which are stimulated by the mycotoxin.

Increased mycotoxin risks through byproducts? Invest in mitigation solutions

To prevent the detrimental consequences of mycotoxins on animal health and performance, proactive solutions are needed that support the intestinal epithelium’s digestive and immune functionality and help maintain a balanced microbiome in the GIT. As the current market conditions will likely engender a long-term shift towards the inclusion of more cereal byproducts in animal diets, this becomes even more important.

Trial data shows that EW Nutrition’s toxin-mitigating solution SOLIS MAX provides effective protection against feedborne mycotoxins. The synergistic combination of ingredients in SOLIS MAX mycotoxins from damaging the animals’ gastrointestinal tract and entering the blood stream:

In-vitro study shows SOLIS MAX’ strong mitigation effects against wide range of mycotoxins

Animal feed is often contaminated with two or more mycotoxins, making it important for an anti-mycotoxin agent to be effective against a wide range of different mycotoxins. A dose response evaluation of SOLIS MAX was conducted a at an independent laboratory in Spain, for inclusion levels of 0.10%, 0.15%, and 0.20% (equivalent to 1 kg, 1.5 kb, and 2 kg per ton of feed). A phosphate buffer solution at pH 7 was prepared to simulate intestinal conditions in which a portion of the mycotoxins may be released from the binder (desorption).

Each mycotoxin was tested separately by adding a challenge to buffer solutions, incubating for one hour at 41°C, to establish the base line (see table). At the same time a solution with the toxin challenge and SOLIS MAX was prepared, incubated, and analyzed for the residual mycotoxin. All analyses were carried out by high performance liquid chromatography (HPLC) with standard detectors.

Figure 3: SOLIS MAX adsorption capacity against different mycotoxins (%)

The results demonstrate that SOLIS MAX is a very effective solution against the most common mycotoxins found in raw materials and animal feed, showing clear dose-response effects.

Mycotoxin risk management for better animal feed

A healthy gastrointestinal tract is crucial to animals’ overall health: it ensures that nutrients are optimally absorbed, it provides effective protection against pathogens through its immune function, and it is key to maintaining a well-balanced microflora. Even at levels considered safe by the European Union, mycotoxins can compromise different intestinal functions, resulting in lower productivity and susceptibility to disease.

The globalized feed trade, which spreads mycotoxins beyond their geographical origin, climate change and raw material market pressures only escalates the problem. On top of rigorous testing, producers should mitigate unavoidable mycotoxin exposures through the use of solutions such as SOLIS MAX – for stronger animal health, welfare, and productivity.

References

Antonissen, Gunther, An Martel, Frank Pasmans, Richard Ducatelle, Elin Verbrugghe, Virginie Vandenbroucke, Shaoji Li, Freddy Haesebrouck, Filip Van Immerseel, and Siska Croubels. “The Impact of Fusarium Mycotoxins on Human and Animal Host Susceptibility to Infectious Diseases.” Toxins 6, no. 2 (January 28, 2014): 430–52. https://doi.org/10.3390/toxins6020430.

Burel, Christine, Mael Tanguy, Philippe Guerre, Eric Boilletot, Roland Cariolet, Marilyne Queguiner, Gilbert Postollec, et al. “Effect of Low Dose of Fumonisins on Pig Health: Immune Status, Intestinal Microbiota and Sensitivity to Salmonella.” Toxins 5, no. 4 (April 23, 2013): 841–64. https://doi.org/10.3390/toxins5040841.

Burton, Emily J., Dawn V. Scholey, and Peter E. Williams. “Use of Cereal Crops for Food and Fuel – Characterization of a Novel Bioethanol Coproduct for Use in Meat Poultry Diets.” Food and Energy Security 2, no. 3 (September 19, 2013): 197–206. https://doi.org/10.1002/fes3.30.

Ghareeb, Khaled, Wageha A. Awad, Josef Böhm, and Qendrim Zebeli. “Impacts of the Feed Contaminant Deoxynivalenol on the Intestine of Monogastric Animals: Poultry and Swine.” Journal of Applied Toxicology 35, no. 4 (October 28, 2014): 327–37. https://doi.org/10.1002/jat.3083.

Mani, V., T. E. Weber, L. H. Baumgard, and N. K. Gabler. “Growth and Development Symposium: Endotoxin, Inflammation, and Intestinal Function in livestock1,2.” Journal of Animal Science 90, no. 5 (May 1, 2012): 1452–65. https://doi.org/10.2527/jas.2011-4627.

Obremski, K. “The Effect of in Vivo Exposure to Zearalenone on Cytokine Secretion by Th1 and Th2 Lymphocytes in Porcine Peyer’s Patches after in Vitro Stimulation with LPS.” Polish Journal of Veterinary Sciences 17, no. 4 (2014): 625–32. https://doi.org/10.2478/pjvs-2014-0093.

Oswald, I. P., C. Desautels, J. Laffitte, S. Fournout, S. Y. Peres, M. Odin, P. Le Bars, J. Le Bars, and J. M. Fairbrother. “Mycotoxin Fumonisin B1 Increases Intestinal Colonization by Pathogenic Escherichia Coli in Pigs.” Applied and Environmental Microbiology 69, no. 10 (2003): 5870–74. https://doi.org/10.1128/aem.69.10.5870-5874.2003.

Pinotti, Luciano, Matteo Ottoboni, Carlotta Giromini, Vittorio Dell’Orto, and Federica Cheli. “Mycotoxin Contamination in the EU Feed Supply Chain: A Focus on Cereal Byproducts.” Toxins 8, no. 2 (February 15, 2016): 45. https://doi.org/10.3390/toxins8020045.

Pinton, Philippe, and Isabelle Oswald. “Effect of Deoxynivalenol and Other Type B Trichothecenes on the Intestine: A Review.” Toxins 6, no. 5 (May 21, 2014): 1615–43. https://doi.org/10.3390/toxins6051615.

By Marisabel Caballero, Global Technical Manager Poultry, and Dr. Inge Heinzl, Editor, EW Nutrition

Consistently rising feed prices compel feed producers to resort to alternative feed ingredients. By-products of milling and ethanol distillation would be good options. The following article shows what should be paid attention to when using these feeds.

Keeping high-quality animal protein affordable requires cost-efficient alternatives

For a high percentage of consumers, the price of food products is one of the most decisive purchase factors; however, quality and sustainable use of resources are also of high importance. So, to comply with market requirements, meat producers must find cost-efficient and sustainable sources of feed ingredients. Feed prices already increased during the COVID-19 pandemic. Shortage of workforce and high shipping costs led to discontinuity in the supply chain, long delivery times, and increased costs for certain raw materials. Due to the Ukrainian crisis, there is no improvement to be seen. Alternatives must be considered more vigorously to compensate for this limited feed supply.

Grain by-products are an option

The use of grain by-products occurring at milling or ethanol production can cover a part of animal nutritional demands. Additionally, it contributes to sustainable usage of the available sources, as the remains of the production of human consumables are put back into the food chain.

However, increasing levels of by-products in the feed also have their sticking points. The raw materials grains or corn are often contaminated with mycotoxins, impacting the quality of this kind of feed.

Milling processes reduce mycotoxins in food

Before the whole process of milling, the grains are sorted and cleaned. Kernels with extensive mold growth, broken kernels, fine materials, and dust are removed.

When it comes to reducing mycotoxins by sorting and cleaning, the results vary a lot. They are influenced by several factors, including the initial condition of the grains, the type and level of contamination, and the type and efficiency of the cleaning process (Pinotti et al., 2016). The cleaning process has been shown to remove from 5 to 80 % of DON and NIV, 5 to 40 % of ZON (Schaarschmidt & Fauhl-Hassek, 2018), and 50 to 60 % of T2/HT2 contamination in wheat (Pascale et al., 2011). Debranning, the mechanical process by which the outer layers of wheat grains are removed, further reduces mycotoxin content in wheat grain from 15 to 80% of the initial contamination (Aureli et al., 2007; Rios et al., 2009). However, neither the cleaning and debranning nor the milling process include a step that destroys mycotoxins.

In white flour for human consumption, mycotoxin levels typically range from 50 to 70% of the wheat grain (Cheli et al., 2013).

The milling of maize shows a reduction factor of about 4 for aflatoxins and about 10 for zearalenone from the grain to the final human products. Contrarily, concentration triplicates for both aflatoxins and zearalenone in the case of the by-products such as germs, bran, and animal flour.

Milling processes concentrate mycotoxins in animal-feed fractions

The milling and pre-milling processes reduce the content of mycotoxins in products for human consumption, but what about the parts removed and normally used in animal feeds? Several studies (Tibola et al., 2015; Hoffmans et al., 2022) indicate that the concentration of mycotoxins is higher in the wheat fractions intended for animal feeds such as bran, flour shorts screenings, and middlings. However, their level in feedstuffs is variable and affected by several factors such as the type of mycotoxins, the level and extent of fungal contamination, and the complexity of the cereal processing technology.

Compared to the concentration in wheat grain, these concentrations in by-products may be up to 800 % but more typically range from 150 % to 340 % (Cheli et al., 2013). EW Nutrition’s worldwide mycotoxin survey shows a similar trend (Figures 1 and 2), in which DON levels are nine times higher in wheat midds than wheat grains, and fumonisin is eight times higher in wheat bran.

Figure 1 + 2: Mycotoxins levels in grain and by-products

Highest concentrations in germ and bran fraction

After corn milling, animal feed fractions such as germ and bran have a low yield ranging from 5 to 7 % and are mostly composed of the outer parts of the kernels; as a consequence, an important concentration of mycotoxins occurs in these fractions (Schollenberger et al., 2008). When taking corn grains as the base, the contamination of aflatoxins goes up to three times in corn germ and up to nine times in bran (Brera et al., 2006; Pietri et al., 2009). For fumonisins, a double concentration can be expected (Brera et al., 2004), and for zearalenone, up to four times (Brera et al., 2006). Recently, Park and collaborators (2018) evaluated the distribution of 12 mycotoxins during wet milling of corn and found higher concentrations in corn gluten feed and corn bran.

Milling is a crucial step in the post-production of rice, in which the husk and the bran layers are removed. Rice bran is a common ingredient for animal feeds, in which aflatoxin is a common contaminant. It is believed that most of the aflatoxin contamination in rice bran occurs due to non-optimal storage conditions (Takahashi et al., 1989); however, a concentration of the toxin during milling of stored paddy rice also occurs, and the levels can triplicate compared with the grains (Trucksess et al., 2011).

The concentration of mycotoxins in DDGS during the ethanol production

Destillers’ dried grains with solubles (DDGS), a by-product of ethanol production, is a valuable feed ingredient, particularly as a source of protein for ruminants and monogastric animals at a competitive price.

Also here, mycotoxin contamination raises concerns with regard to their use in animal feeds. Mycotoxins are not destroyed during the ethanol fermentation process or during the production of DDGS. Moreover, a concentration of DON, ZEA, and fumonisin from corn to DDGS of 2–3.5 times has been reported for industrial ethanol production (Bennett et al., 1981; Schaafsma et al., 2009; Bowers & Munkvold, 2014).

In summary, studies on the fate of mycotoxins during food processing have shown that mycotoxins are concentrated in the fractions commonly used as animal feed. Moreover, high variability in mycotoxin contamination of cereal by-products has been evidenced, representing barriers to an increased acceptance of several food by-products as feed ingredients.

Feed formulation: Consider the mycotoxin contamination in by-products

Higher inclusions of cereals have an impact on their safe use in feeds. To evaluate this impact, we can simulate two different scenarios with different inclusions of by-products:

Table 1: Different levels of by-products’ inclusion rates

*Risk Tool (masterrisktool.com)

In the first lower inclusion scenario, the risk for broilers in the starting phase considers the low inclusion of raw materials; the losses related to the contamination (without management) are mild. When increasing the levels of by-products, the risk category also increases. The losses are more important for the operation, ranging from gut barrier alterations with impaired production parameters to alterations in the immune response and increased susceptibility to disease.

Mycotoxins in by-products effective toxin risk management can help!

Given the pros of including cereal by-products in animal feeds, such as their saving potential and their link with sustainability of resources, their utilization is advisable; however, understanding how mycotoxin distribution and concentration change during grain processing is critical. Today’s knowledge is limited to a few mycotoxins in cereal milling.

Therefore, when considering using these by-products in the animal feed, we must bear in mind that:

• modified mycotoxins and mycotoxin co-contamination can be present, contributing to additive/synergistic effects on animal health.
• toxin risk management strategies, including analysis, risk evaluation, and risk mitigation must be pursued to prevent those undesired effects.

References:

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Bennett, G. A., A. A. Lagoda, O. L. Shotwell, and C. W. Hesseltine. “Utilization of Zearalenone- Contaminated Corn for Ethanol Production.” Journal of the American Oil Chemists’ Society 58, no. 11 (1981): 974–76. https://doi.org/10.1007/bf02659774.

Bowers, Erin, and Gary Munkvold. “Fumonisins in Conventional and Transgenic, Insect-Resistant Maize Intended for Fuel Ethanol Production: Implications for Fermentation Efficiency and DDGS Co-Product Quality.” Toxins 6, no. 9 (2014): 2804–25. https://doi.org/10.3390/toxins6092804.

Brera, Carlo, Carla Catano, Barbara de Santis, Francesca Debegnach, Marzia de Giacomo, Elena Pannunzi, and Marina Miraglia. “Effect of Industrial Processing on the Distribution of Aflatoxins and Zearalenone in Corn-Milling Fractions.” Journal of Agricultural and Food Chemistry 54, no. 14 (2006): 5014–19. https://doi.org/10.1021/jf060370s.

Brera,Carlo, Francesca, Debegnach, Silvana Grossi, and Marina Miraglia. “Effect of Industrial Processing on the Distribution of Fumonisin B1 in Dry Milling Corn Fractions.” Journal of Food Protection 67, no. 6 (2004): 1261–66. https://doi.org/10.4315/0362-028x-67.6.1261.

Cheli, Federica, Luciano Pinotti, Luciana Rossi, and Vittorio Dell’Orto. “Effect of Milling Procedures on Mycotoxin Distribution in Wheat Fractions: A Review.” LWT – Food Science and Technology 54, no. 2 (2013): 307–14. https://doi.org/10.1016/j.lwt.2013.05.040.

Park, Juhee, Dong-Ho Kim, Ji-Young Moon, Jin-Ah An, Young-Woo Kim, Soo-Hyun Chung, and Chan Lee. “Distribution Analysis of Twelve Mycotoxins in Corn and Corn-Derived Products by LC-MS/MS to Evaluate the Carry-over Ratio during Wet-Milling.” Toxins 10, no. 8 (2018): 319. https://doi.org/10.3390/toxins10080319.

Pascale, Michelangelo, Miriam Haidukowski, Veronica Maria Lattanzio, Marco Silvestri, Roberto Ranieri, and Angelo Visconti. “Distribution of T-2 and HT-2 Toxins in Milling Fractions of Durum Wheat.” Journal of Food Protection 74, no. 10 (2011): 1700–1707. https://doi.org/10.4315/0362-028x.jfp-11-149.

Pietri, A., M. Zanetti, and T. Bertuzzi. “Distribution of Aflatoxins and Fumonisins in Dry-Milled Maize Fractions.” Food Additives & Contaminants: Part A 26, no. 3 (2009): 372–80. https://doi.org/10.1080/02652030802441513.

Pinotti, Luciano, Matteo Ottoboni, Carlotta Giromini, Vittorio Dell’Orto, and Federica Cheli. “Mycotoxin Contamination in the EU Feed Supply Chain: A Focus on Cereal Byproducts.” Toxins 8, no. 2 (2016): 45. https://doi.org/10.3390/toxins8020045.

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By Dr. Inge Heinzl, Editor, and Marisabel Caballero, Global Technical Manager Poultry, EW Nutrition

Careful management of the breeders is a must to get their best reproductive efficiency. In today’s hatching egg production, factors such as stress, inflammation, body weight, and altered mating behavior lead to decreased performance, meaning fewer hatchable eggs and, therefore, fewer day-old chicks per hen (Grandhaye, 2020). The use of antibiotics to increase performance in farm animals is no longer allowed in many countries, and, since it may lead to the development of resistance, it is also not recommended. So, also in breeders, alternatives are requested to maintain animal health, welfare, and a high level of performance. 

Optimal gut health is the cornerstone for breeder performance 

As the organ responsible for digestion of the incoming feed, the absorption of nutrients, and the defense of the organism against pathogens or toxins, a healthy gut is a pre-condition for optimal performance (Shini and Bryden, 2021). A healthy gut, according to Bailey (2018), has optimally developed gut tissues, a well-functioning gut immune system, and well-balanced gut microbiota. It shows efficient functionality in terms of digestion and absorption and protects the organism against harmful agents. 

The gut directly or indirectly provides the elements for egg production 

Efficient feed digestion and absorption of nutrients are essential for the breeder hen to obtain the “material” for maintenance, growth, and egg production. Gut health is crucial since dysbacteriosis and diarrhea, characteristics of gut health challenges, increase dirty eggs, creating favorable conditions for pathogens to enter the egg and infect the embryo. 

Egg yolks consist of water (70%), proteins (10%), and lipids (20%). The yolk lipids are lipoproteins rich in triglycerides, built up in the liver and transported to the ovary. Cholesterol carried via lipoproteins to the egg yolk is also built up there, thus showing the importance of the liver in egg production. The gut plays a crucial role in protecting the liver from damage, constituting a barrier against harmful pathogens and toxins, potentially passing into the bloodstream and reaching this vital organ.  

Phytomolecules support performance in different ways 

Phytomolecules, are an excellent tool to support gut health and animal performance. Phytomolecules are plant-derived secondary metabolites that exert insect-attracting or defensive functions in the plant. They are used in their natural but also nature-identical forms in humans and animals to exert their digestive, immune-modulating, antimicrobial effects. 

Phytomolecules support gut health by balancing the gut microbiome 

Diverse examples can be found in the scientific literature, where phytomolecules improve the gut microbiome, resulting in better performance of layer and breeder hens. This support happens in two ways: 

1. Promoting beneficial bacteria

   Rabelo-Ruiz and co-workers (2021), asserted that adding garlic and onion extracts to the diet of layers led to more eggs with a bigger size, accompanied by an increase in Lactococci in the ileum and Lactobacilli in the cecum. Another example is provided by Park et al. (2016). When supplementing the diet of layers with a fermented phytogenic feed additive, egg production and weight raised with increasing dosage of the additive, and a higher number of Lactobacilli could be observed in the cecum.  
   Phytomolecules can promote the growth of certain beneficial bacteria and therefore act like prebiotics. As these changes took place in the lower gut, they assumed an improved digestibility of the feed. 

2. Lowering pathogenic bacteria

   In the study by Park et al. (2016) and in an in vitro study by Ghazanfari et al. (2019), E. coli in the cecum was reduced.  

   According to Burt (2007b), several essential oils / phytomolecules, amongst them, carvacrol, thymol, eugenol, and cinnamaldehyde, are effective against pathogens such as Listeria, Salmonella, E. coli, Shigella, and Staphylococcus. The hydrophobic essential oils can partition the lipids of the cell membranes. The resulting permeability of the membrane enables the leakage of cell content.  

3. Changing virulence factors

   Another mode of action is the change of virulence factors. Carvacrol, e.g., is known to decrease the motility of Campylobacter jejuni (Van Alphen et al., 2012); oregano and thyme oil reduced the motility of E. coli by inhibiting the synthesis of flagellin (Burt, 2007a). Vidanarachchi et al. (2005) mentioned that the hydrophobicity of microbes increases when some plant extracts are present, affecting their virulence characteristics. Also, the inhibition of defense measures such as efflux pumps in Gram-negative bacteria has been researched (Savoia, 2012). 

Phytomolecules support gut health by improving digestion 

For many years, phytomolecules have been studied and known for their digestive characteristics. In poultry and other animals, they influence feed digestion in two main ways. 

1. Stimulating enzyme secretion

   Platel and Srinivasan (2004) described different spices promoting not only the salivary flow, gastric juice and bile secretion but also the stimulation of the activity of enzymes such as pancreatic lipase, amylase, and proteases in rats. Hashemipour et al. (2013) saw the same effect in broilers supplemented with carvacrol and thymol in the diet. Research has also concluded on a higher nutrient digestibility:  Hernandez et al. (2004) and Basmacioğlu Malayoğlu, 2010 noticed that supplementing plant extracts or essential oils improved apparent whole-tract and ileal digestibility of different nutrients.). 

2. Maintaining gut integrity and enlarging the digestion area

   An intact gut with a large area for digestion guarantees optimal utilization of nutrients. Different researchers found that adding plant extracts or essential oils (Khalaji et al., 2011; Ghazanfari et al., 2015; Chowdhury et al., 2018) promotes intestinal gut morphology, reflected in higher villi and deeper crypts, which might lead to higher nutrient absorption.

   Concerning gut integrity, thymol and carvacrol showed protecting effects and mitigated gut lesions in broilers challenged with C. perfringens (Du et al., 2016). Probably, the lower pathogenic pressure due to the antimicrobial activity of phytogenic substances leads to minor damage to the gut wall and, in the end, to better absorption of the nutrients.  

Phytomolecules mitigate the effects of stress 

Environmental stress in breeders may decrease performance: the heat-stress-induced disruption of the tight junctions often leads to higher gut permeability, poor nutrient absorption, and higher electrolyte and water secretion (Abdelli, 2021). Sahin et al. (2010) achieved a linear improvement in egg production in quails when applying two doses of green tea catechin.  

Cold-stressed layers also reacted positively to supplementation of oregano essential oil, improving egg production compared to a non-supplemented control (Migliorini, 2019). 

Positive influence of phytomolecules results in higher performance 

As described, phytomolecules improve gut health and support the animal in multiply ways, allowing better utilization of resources for growth and production. Literature provides many articles showing the promoting effects of these substances on the performance of layers or breeders, some of them summarized in Table 1.  

Table 1: Benefits of phytomolecules in layers and breeders 

In-feed and in-water phytomolecules-based products show efficacy 

Much of the research done with phytomolecules focuses on essential oils (with variable inclusions of the active compounds or on single plant extracts. EW Nutrition is a research-driven company proposing phytomolecule-based solutions for the animal production industry. These products combine selected, synergistically acting phytomolecules to achieve optimal results.   

EW Nutrition has tested the combined use of  

• a microencapsulated blend of phytomolecules (Activo) for the feed and designed to maintain a good gut-health status during the whole life-cycle of the breeders, and  

• Activo Liquid, a liquid combination of phytomolecules and organic acids, which is conveniently applied on the farm via the waterline.  

1. Trial documents phytomolecules positively influencing microflora 

A trial conducted at the University of Central Queensland (Australia) showed that phytomolecules enhance beneficial bacteria such as Lactobacilli and, on the other hand, repress harmful bacteria such as Clostridium perfringens.  

For the trial, caecal microbiota of layers was used. They were grown with and without Activo Liquid in vitro, and the changes in microbiota were monitored. 

Result: The in vitro study clearly shows that Activo Liquid increases the number of lactobacilli and decreases clostridia and Enterococcus sp.  

Figure 1: Shifting intestinal balance with phytomolecules 

2.Three field trials with Activo Liquid showed an increased laying rate in breeders

 Many operations started testing phytomolecules in a farm-application-based program to reaffirm the gut health-improving activity of phytomolecules in broiler breeder performance. Especially the flexibility of assisting animals through the water for drinking during stress periods makes phytomolecules an optimal tool to support gut health.   

Two broiler breeder farms in Thailand (TH1 and TH2) and one grandparent farm in India (IN) are good examples of the effectiveness of phytomolecules. On each farm, the birds were always divided into two groups. Besides the standard management, feed, and water, one group got 200 ml Activo Liquid per 1,000 L of water. The periods when the birds received Activo in the water differed: 

TH1 & TH2: 5 days per week, during weeks 24 – 32 

IN:  5 days per week, every third week  from weeks 18 to 24 and every fourth week from 28 to 36  

The trials lasted for 9 weeks (Thailand 1 and 2) and 30 weeks (India). 

The results are shown in figure 2. The animals supplemented with Activo Liquid showed an up to 4.4 % higher laying rate and up to three more hatchable eggs per hen housed. 

Figure 2+3: Results of three trials conducted In Asia concerning laying rate and hatchable eggs 

3. Customers tell about lower breeder mortality and more DOCs due to phytomolecules 

The benefits of a tailored phytomolecule program have been demonstrated in several broiler breeder operations worldwide. For example, a combination of the in-feed (Activo) and the in-water solution (Activo Liquid) was tested in the Middle East. For the study, 75,000 23-weeks-old broiler breeders were divided into groups: 4 houses with the program, and 6 houses served as control (standard feed and water). The program, tailored to customer needs, was designed as follows: 

AC+AL group:

• Activo 100 g/ton of feed during the whole trial (weeks 23-41) + 
• Activo Liquid 250 ml/1000 L water, four days per week, weeks 23-30.  

As a result, the peak and average laying rates were higher for the flocks with the program, and laying persistency was also higher. This allowed for a significant difference of 3 total and 3.5 hatching eggs/hen housed at week 41. In both cases, an increase equivalent to 5 % compared to the control group (figure 4) could be observed. 

Figure 4: Total eggs and hatching eggs per hen housed

As fertility and hatchability were similar for both groups, the 5 % increase in hatching eggs resulted in a 5 % higher number of day-old chicks per hen housed (figure 5).

Figure 5: Number of DOSs per hen housed 

It must be mentioned that during the trial period, at 28 weeks of age, an NDV outbreak was diagnosed on the farm, which negatively impacted the overall results. However, this impact was reduced in the groups receiving the phytomolecule-based products, which also was reflected in a lower mortality rate (figure 6). 

Figure 6: Cumulative mortality rate wk 41

4. Scientific trial shows that Activo can increase post-peak productivity in breeders 

When thinking about the use of phytomolecules, most broiler breeder operations would like to consider scientific trial results in this type of animal. For EW Nutrition, it is crucial to accurately evaluate every product that reaches a market. Thus several scientific trials with broiler breeders have been performed. For one of them, Hubbard breeders (JA57 females with 80 M77 males) were divided into 2 treatments, having 5 replicate pens for each. The experiment started after the peak production period, at 34 weeks of age, and ended at week 62. To make the trial fair, the production data of 6 (pre-experimental) weeks was used to allocate the pens for each treatment, resulting in two (statistically) similar groups. 

The control group was fed the standard mash diet. For the Activo group, 100g Activo/MT was added to the diet. 

With Activo, breeders kept their high productivity after the peak, while the control group showed a steady decline from breed target values. During the experiment, Activo supplemented birds produced 3.6 more eggs than control birds (P=0.06) while consuming a similar amount of feed. As a result, a lower feed consumption per egg produced was achieved (169.9 vs. 173.6 g/egg, respectively). 

As the dietary treatment did not influence hatchability, the 3.6 extra eggs resulted in 2.9 extra day-old chicks per hen during the post-peak period, showing a positive return. 

Phytomolecules as gut health and performance promoters– antibiotics can be reduced! 

With their gut health-promoting activity, phytomolecules support breeders to better utilize nutrients. They can be invested for maintenance and the production of hatchable eggs, obtaining good quality day-old chicks.  

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Ren, Hao, Wilfried Vahjen, Temesgen Dadi, Eva-Maria Saliu, Farshad Goodarzi Boroojeni, and Jürgen Zentek. “Synergistic Effects of Probiotics and Phytobiotics on the Intestinal Microbiota in Young Broiler Chicken.” Microorganisms 7, no. 12 (2019): 684. https://doi.org/10.3390/microorganisms7120684.  

Sahin, K., C. Orhan, M. Tuzcu, S. Ali, N. Sahin, and A. Hayirli. “Epigallocatechin-3-Gallate Prevents Lipid Peroxidation and Enhances Antioxidant Defense System via Modulating Hepatic Nuclear Transcription Factors in Heat-Stressed Quails.” Poultry Science 89, no. 10 (2010): 2251–58. https://doi.org/10.3382/ps.2010-00749.  

Savoia, Dianella. “Plant-Derived Antimicrobial Compounds: Alternatives to Antibiotics.” Future Microbiology 7, no. 8 (2012): 979–90. https://doi.org/10.2217/fmb.12.68.  

Shini, S., and W. L. Bryden. “Probiotics and Gut Health: Linking Gut Homeostasis and Poultry Productivity.” Animal Production Science, 2021. https://doi.org/10.1071/an20701.  

van Alphen, Lieke B., Sara A. Burt, Andreas K. Veenendaal, Nancy M. Bleumink-Pluym, and Jos P. van Putten. “The Natural Antimicrobial Carvacrol Inhibits Campylobacter Jejuni Motility and Infection of Epithelial Cells.” PLoS ONE 7, no. 9 (2012). https://doi.org/10.1371/journal.pone.0045343.  

Vidanarachchi, J.K., L.L. Mikkelsen, I. Sims, P.A. Iji, and M. Choct. “Phytobiotics: Alternatives to Antibiotic Growth Promoters in Monogastric Animal Feeds.” Recent Advances in Animal Nutrition in Australia 15 (2005): 131–44.  

Wang, Xiao-cui, Xiao-hong Wang, Jing Wang, Hao Wang, Hai-jun Zhang, Shu-geng Wu, and Guang-hai Qi. “Dietary Tea Polyphenol Supplementation Improved Egg Production Performance, Albumen Quality, and Magnum Morphology of Hy-Line Brown Hens during the Late Laying period1.” Journal of Animal Science 96, no. 1 (2018): 225–35. https://doi.org/10.1093/jas/skx007.  

Zhu, Nianhua, Jun Wang, Longfei Yu, Qiman Zhang, Kai Chen, and Baosheng Liu. “Modulation of Growth Performance and Intestinal Microbiota in Chickens Fed Plant Extracts or Virginiamycin.” Frontiers in Microbiology 10 (2019). https://doi.org/10.3389/fmicb.2019.01333.  

By Marisabel Caballero, Global Technical Manager Poultry, and Ivan Ilić, Global Manager Technical Product Applications, EW Nutrition

Modern large-scale feed mills operate extremely efficiently and have few variable costs that could be reduced to lower the total cost of the final feed (Stark, 2012). In light of worrying energy price hikes, feed producers, however, should reduce their electricity use per unit produced, to maintain profitability. Find out how optimizing the feed mill’s moisture management increases feed quality while decreasing the energy required to produce it.

Due to climatic challenges, variability in raw material quality, and technical constraints, it can be challenging for feed producers to stabilize the water content in compound feed across time, raw material batches or even different machinery.

Combined with high temperatures, high moisture in feed can favor the growth of molds. They spoil feed, depleting energy and nutrients and generating reactive oxygen species (ROS) that reduce feed palatability. Even worse, some molds release toxins harm animals’ health and performance. On the other hand, low moisture levels in feed has a negative impact on pellet durability, increasing fines, process loss, and energy consumption while decreasing pellet press yield (Moritz et al., 2002).

What does feed moisture management have to do with a feed mill’s electricity consumption?

Moisture from raw materias can be lost during storage and processing. Silo aeration and enviroment conditions can contribute to moisture loss when the grains are stored at higher than optimal moisture levels (Angelovič, 2018). During feed processing, the intense friction of grinding results in heat and moisture from the grains is lost as vapor. As an optimal level of moisture is critical to ensure production output and feed quality, it must be added back to the system and adequately managed to keep or increase final feed quality.

For pelleted feeds, managing moisture is a two-step process:

1. Adding moisture in the mixer. This ensures that the mash feed is enters the conditioning process at the right moisture level, facilitating the penetration of steam and increasing the efficiency of the process.
2. Managing steam during conditioning. Steam added to the conditioner must be dry (meaning saturated with water droplets in suspension), and when this dry steam contacts the feed, it condenses and adds moisture.

However, simply adding water into the mixer does not give optimal results: Pure water does not completely bind to the feed; it mostly “sits on top” of the feed surface, increasing its water activity, and thus increasing the danger of microbial growth. Plus, a high proportion of pure water evaporates again when the feed is cooled.

Surfactants improve moisture retention

Surfactants change the way water behaves: by reducing the surface tension of water, they enable the feed particles to absorb the water and ensure that it is evenly distributed throughout the feed.

Improved moisture retention can:

• facilitate the starch gelatinization during conditioning (important making the pellet more durable and the feed more digestible),
• minimize feed shrinkage,
• reduce friction and hence the energy required for the pellet die (improving milling efficiency), and
• curb microbial growth by reducing water activity.

SURF•ACE: Improve throughput and reduce energy requirements

While surfactants contribute to mold control, feed producers also require the help of organic acids such as propionic acid (cf. Smith et al., 1983). The objectives are to optimize the moisture content in feed and to reduce its mold contamination. EW Nutrition’s SURF•ACE^TM feed mill processing aid combines organic acids and surfactants to achieve the objective of adding moisture without risking either the significant loss of moisture during cooling or the development of mold.

The effect of adding SURF•ACE to diets with different levels of fat was evaluated at more than 40 feed mills, with production capacities ranging from 5 to 20 tons per hour. SURF•ACE is added to water sprayed during mixing. This hydrating solution lubricates the mash feed, improves steam penetration and starch gelatinization, and reduces friction in the pellet dies. The results show that, relative to pure water, the addition of SURF•ACE increases press throughout (t/h) by between 5 and 25 %.

Trial results: SURF•ACE increases press yields while lowering energy consumption

• For a trial at a Turkish beef and poultry feed mill, the same feed was run through the pelletizer in two batches, one with a 1 % water and one with 1% water mixed with 200 g of SURF•ACE per ton of feed. Adding SURF•ACE resulted in higher pellet output (6% for beef; 9% for poutry) and reduced energy consumption (13% for both beef and poultry):

• In Poland, another trial conducted at a commercial feed mill found that when SURF•ACE was added to 1% mixer-moisture, this lead to a 28.6 % higher feed throughput in the pellet press, 23 % lower energy consumption per unit produced during the pelleting process, and a nearly 1 %-point higher moisture content in finished feed. This resulted in higher profitability: based on the costs in Poland at the time of the trial, an ROI of 2.4:1 was achieved.

• A recent trial at an Indian feed mill evaluated the difference between adding 1% moisture to produce crumble feed (control group) and upgrading the water with 200 g of SURF•ACE per ton. The addition of SURF•ACE reduced power consumption by 6% and improved throughput by 18%.

Feed mills must deal with rising energy costs head-on

Operating in a tight margin environment, feed mills always need to prioritize efficiency. The advantages of using SURF•ACE feed mill processing aid are clear: reduced energy consumption, better pellet quality, fewer fines, better PDI, moisture optimization, lower maintenance costs, and higher productivity (throughput). During times of increasingly high ingredient and energy costs, it is even more important to utilize savings opportunities at every production stage. Thanks to its dual surfactant and preservative effects, SURF•ACE enables feed mills to improve feed quality and increase throughput while lowering electricity use.

References

Angelovič, Marek, Koloman Krištof, Ján Jobbágy, Pavol Findura, and Milan Križan. “The effect of conditions and storage time on course of moisture and temperature of maize grains.” BIO Web Conferences 10 (2018): 02001. https://doi.org/10.1051/bioconf/20181002001

Moritz, J. S., K. J. Wilson, K. R. Cramer, R. S. Beyer, L. J. McKinney, W. B. Cavalcanti, and X. Mo. “Effect of Formulation Density, Moisture, and Surfactant on Feed Manufacturing, Pellet Quality, and Broiler Performance.” Journal of Applied Poultry Research 11, no. 2 (2002): 155–63. https://doi.org/10.1093/japr/11.2.155.

Smith, Philip A., Talmadge S. Nelson, Linda K. Kirby, Zelpha B. Johnson, and Joseph N. Beasley. “Influence of Temperature, Moisture, and Propionic Acid on Mold Growth and Toxin Production on Corn.” Poultry Science 62, no. 3 (1983): 419–23. https://doi.org/10.3382/ps.0620419.

Stark, Charles. “Feed manufacturing to lower feed cost”. Presentation at Allen D. Leman Swine Conference, Volume 39, 2012. https://conservancy.umn.edu/bitstream/handle/11299/139624/Stark.pdf?sequence=1

By Technical Team, EW Nutrition

A variety of stressors simultaneously occur at weaning, making this probably the most challenging period in pig production. During weaning, we commonly see altered gut development and gut microbiome, which increases piglets’ vulnerability to diseases. The most classic clinical symptom resulting from these stressors is the occurrence of post-weaning diarrhea. It is a sign that something went wrong, and piglet development and overall performance may be compromised (Guevarra et al. 2019).

Besides weaning, an unavoidable practice in pig production, the swine industry has been facing other changes. Among them, the increased pressure to reduce the use of antimicrobials stands out. Antimicrobials are often associated with improved piglet performance and health. Their usage has been reduced worldwide, however, due to the threat of antimicrobial resistance that affects not just animal health but also human health (Cardinal et al., 2019).

Reduce antimicrobials and post-weaning diarrhea: can piglet nutrition achieve both?

With these drastic changes for the piglets and the global swine industry, producers must find solutions to keep their farms profitable — especially from a nutritional perspective. Our last article presented two feed additives that can be part of an antibiotic-free concept for post-weaning piglets. This article will highlight a few essential nutritional strategies that swine producers and nutritionists must consider when formulating post-weaning feed without or with reduced amounts of antimicrobials.

What makes weaning so stressful for piglets?

Producers, nutritionists, and veterinarians all agree that weaning is a tough time for piglets (Yu et al., 2019) and, therefore, a challenge to all those involved in the pig production chain. Although there is a global trend towards increasing weaning age, generally speaking, animals are still immature when going through the weaning process. They face several physiological, nutritional, and environmental changes (figure 1).

Figure 1. Factors associated with weaning can compromise piglet well-being and performance

Most of these changes become “stressors” that trigger a cascade of reactions affecting the balance and morphology of the intestinal microbiome (figure 2). The outcome is a decrease in the piglets’ well-being and, in most cases, performance. We need to clearly understand how these stressors affect pigs to develop effective strategies against post-weaning growth impairments, especially when no antimicrobials are allowed.

Figure 2. Schematic diagram illustrating the effects of stress in weaned piglets (adapted from Jayaraman and Nyachoti, 2017)

Weaning support starts before weaning

The use of creep feed has been evaluated and even criticized for many years. Some operations are still reluctant to use such a feed due to its high cost and amount of labor on the farm, with manually providing feed and cleaning feeding trays. In addition, some questions have been raised regarding the ideal composition of the creep feed – how much complexity should we add to this special diet?

Therefore, the benefits of creep feed are under re-evaluation, not only considering piglet physiology per se, but also feed characteristics and different feeding programs. Recent studies have questioned highly complex creep feed formulations. Creep feed is being called “transition feed” (Molist, 2021) – i.e., that meal which is complementary to sows’ milk and not a replicate of it, helping piglets during the period of changing its main source of nutrients. We must, therefore, look at it as a way of making piglets familiar with solid feed, as highlighted by Mike Tokach during the 2020 KSU Swine Day. Dr. Tokach also mentioned that the presence of feeders in the lactation pen could stimulate the exploratory behaviors of the piglets. Combined, these practices can lead to a higher feed intake and performance during the nursery phase.

Towards a pragmatic stance on creep feed

Heo et al. (2018) evaluated three different creep feed types: a highly digestible creep feed, weaning feed as creep feed, and sow feed as creep feed until weaning. Piglets receiving the highly digestible creep had higher feed intake during the second to the last week pre-weaning (14 to 21 days of age) and higher ADG during the last week pre-weaning (21 to 28 days of age). This resulted in a trend for higher weaning weight. However, these benefits did not persist after weaning when all piglets received the weaning feed.

Guevarra et al. (2019) also suggested that the abrupt transition in piglet nutrition to a more complex nutrient source can influence shifts in the gut microbiota, impacting the absorptive capacity of the small intestine. Yang et al. (2016) evaluated 40 piglets from eight litters during the first week after weaning. They found that the change in diet during weaning reduced the proliferation of intestinal epithelial cells. This indicates that this period affects cellular macromolecule organization and localization, in addition to energy and protein metabolism. These results suggest that “similarity” in feed pre- and post-weaning may contribute more to the continuity of nutrient intake post-weaning than a highly complex-nutrient dense creep feed.

Nutritional strategies without antibiotics: focus on pig physiology

As mentioned, it is crucial to avoid a drastic drop in feed/nutrient intake after weaning compared to pre-weaning levels. In a classic study, Pluske et al. (1996) showed the importance of high intake levels on villus weight (used as a reference for gut health, cf. graph 1). Although not desirable, the reduction should be considered “normal” behavior.

Imagine these recently weaned piglets, facing all these stressors, having to figure out within this new group of peers when it is time to eat, where to find food, why water and food now come from two distinct sources… Therefore, management, feeding, water quality, and other aspects play important roles in post-weaning feed intake (figure 3).

Graph 1. Villus height following different levels of feed intake (M = maintenance) post-weaning (a.b.c bars with unlike superscript letters are different at P<0.05). (From Pluske et al., 1996.)

From a nutritional perspective, piglets at weaning experience a transition from milk (a high-fat, low-carbohydrate liquid) to a plant-based diet (a solid, low-fat, and high-carbohydrate diet) (Guevarra et al., 2019). Even when previously introduced to solid feed, it is still difficult for their enzymatic system to cope with grains and beans.

One of the consequences of the lower digestibility capacity is an increase of undigested nutrients. Harmful bacteria thrive and cause diarrhea, reducing even further an already compromised feed intake. This cycle must be broken with the support of formulations based on piglet physiology.

Post-weaning feed must support digestion and nutrient absorption, including the largest possible share possible of high-quality, digestible ingredients, with low anti-nutritional factors. High-performing feed also integrates functional amino acids, functional carbohydrates, and additives to support the intestinal mucosa and gut microbiome.

Figure 3. Supporting piglets with effective solutions

Crude protein – more of the same?

Levels of crude protein in piglet feed have been in the spotlight for quite some time. The topic can be very controversial where the exact percentage of crude protein in the final feed is concerned. Some nutritionists pragmatically recommend maximal levels of 20% in the weaner feed. Others go a bit lower, with some formulations reaching 17 to 18% total crude protein. Levels above 20% will incur high costs and may accentuate the growth of pathogenic bacteria due to a higher amount of undigested protein in the distal part of the small intestine (figure 4).

Figure 4. The dynamics of crude protein levels in piglet feed

What is not open for discussion, however, is the quality of the protein used, in terms of:

• digestibility,
• the total amount of anti-nutritional factors, and
• the correct supply of essential and non-essential amino acids (particularly lysine, methionine, threonine, tryptophane, isoleucine and valine).

The critical role of digestibility

High-digestibility ingredients for piglets need to deliver minimum 85% digestibility. In most cases, to reach high biological values (correlating to high digestibility), these ingredients typically undergo different processing steps, including heat, physical, and chemical treatments. Animal by-products (such as hydrolyzed mucosa, fish meal, spray-dried plasma) and processed vegetable sources (soy protein concentrate, extruded grains, potato protein) can be used in high amounts during this phase. They will notably reduce the total amount of undigested protein reaching the distal part of the intestine, with 2 main benefits:

• Less substrate for pathogenic bacteria proliferation (and therefore lower incidence of diarrhea)
• Lower nitrogen excretion to the environment

It is common knowledge that certain storage proteins from soybean meal (for instance, glycinin and B-conglycinin) can cause damage to piglets’ intestinal morphology and trigger the activation of the immune system. However, it is normal practice to introduce this ingredient to piglets around weaning so that the animals can develop a certain level of tolerance to such compounds (Tokach et al., 2003). In Europe, where most diets are wheat-barley based, soybean meal is included in levels varying from 3 to 9% in the first 2 diets, with gradual increases during the nursery phase.

Amino acids and protein: manage the balance

When the supply and balance between essential and non-essential amino acids is concerned, reducing total crude protein brings indeed complexity to the formulations. The concept of ideal amino acid should be expanded, ideally, to all 9 essential amino acids (lysine, methionine, tryptophan, threonine, valine, isoleucine, leucine, histidine, and phenylalanine). In most cases, formulations go up to the 5^th or 6^th limiting amino acid. Lawor et al. (2020) suggest 2 practical approaches to avoid deficiencies when formulating low-protein piglet feed:

• Maintain a maximum total lysine to crude protein ratio in the diet of 7.1 to 7.4%
• Do not exceed the SID lysine to crude protein ratio of 6.4%

Some conditionally essential amino acids (e.g. arginine, proline, and glutamine) also play critical roles in diets with reduced crude protein levels. Glutamine is especially interesting. When supplemented in the feed, it can be used as a source of energy by the intestinal epithelium and, therefore, prevent atrophy and support nutrient absorption, resulting in better growth post-weaning (Hanczakowska and Niwińska, 2013; Watford et al., 2015)

The importance of the buffer capacity of the feed – supporting the enzymatic system

Given the move towards antibiotic reduction, this topic is more relevant than ever to nutritionists worldwide. The acid-binding capacity (also known as buffering capacity) of the feed directly affects the capacity of the stomach to digest protein. Hence, buffer capacity is of utmost importance in antimicrobial-free diets as it influences the growth of pathogenic bacteria (Lawlor et al., 2005).

In short, the acid-binding capacity is the resistance of an ingredient or complete feed to pH change. For piglet feed/feed ingredients, it is normally measured by the acid-binding capacity at pH4 (ABC-4). A higher ABC-4 equates to a higher buffering capacity. Feed with a high ABC-4 would require large amounts of gastric acid for the pH of the stomach to reach 4 and below. As the post-weaned piglet has limitations on producing and secreting acid, the stomach pH would stay high and, thus, less favorable for protein digestion.

The recommendation is to have a complete feed based on single ingredients with low ABC-4 values and to use additives that further reduce the ABC-4 value (such as organic acids). According to Molist (2020), post-weaning feed must have an ABC-4 that is lower than 250-300 meq/kg.

Talking about fiber

Dietary fibers are also known for regulating intestinal health in both humans and animals. Chen et al. (2020), for example, examined the effects of dietary soluble fibers (inulin) and insoluble fibers (lignocellulose) in weaned piglet diets for four weeks. Results showed that combining those fibers can positively influence nutrient digestibility, gut microbiota composition, intestinal barrier functions, and growth performance (table 1 ).

Table 1. Effects of dietary fiber supplementation on piglet growth performance (adapted from Chen et al., 2020)

How to reduce antimicrobials? Understand the roles of piglet physiology and nutrition

Swine producers might think that “How can I reduce antimicrobial use on my farm?” and “How can I improve the performance of piglets at weaning?” are two separate questions. However, that is not always the case. Answers based on a deep understanding of physiology and nutrition dynamics help piglets overcome the challenges encountered during weaning – and, thus, lessen the need for antimicrobial interventions.

In this article, we have explored the basic principles that are the basis for ensuring the performance and health of the post-weaning piglet. Although we do not have a singular solution for eliminating antimicrobials on our pig farms, we can count on a group of robust and integrated nutritional strategies. By integrating factors ranging from management to feed additives, these solutions can improve piglet health and performance throughout their lives.

To know more about Gut health products click here.

Piglet weaning is a critical period. When not properly managed, it leads to decreased performance, diarrhea, and sometimes mortality. 

The six areas of intervention in our infographic will help pig producers manage these stressors, avoid diarrhea, and maintain piglet health and performance. 

By Technical Team, EW Nutrition

A storm has been brewing.

Even before the invasion of Ukraine in late February, global growth was expected to trend significantly downward, from 5.5-5.9% in 2021 to 4.1-4.4% in 2022 and 3.2% in 2023. The causes are similar across industries:

• rising inflation around the world
• supply chain issues stretching long into the foreseeable future, including exponentially higher freight costs
• pandemic restrictions and long-lasting effects
• rising raw material prices

In early 2022, this “perfect storm” quickly stifled the moderate optimism of Q4 2021. Of course, the worst was yet to come.

What causes sustained price increases?

With the ongoing crisis in Eastern Europe, economic perspectives are tilting down to a new level of uncertainty. The new variables now thrown into the mix are crude oil and natural gas prices, as well as added concerns over other raw materials coming out of Russia and Ukraine.

Source: tradingeconomics.com, March 2022

Russia accounts for 25% of the global natural gas market and 11% of the crude oil market. It is also the largest wheat exporter (China and India are still the largest producers, but Russia exports appreciably more). Together with Ukraine, also a powerhouse of agricultural exports, the two now enemies account for 29% of international annual wheat sales.

Source: ING, March 2022

Wheat prices were already nearly double the five-year average shortly before the invasion; after February 24, they rose by another 30%. Today we are at a staggering 53% increase in wheat prices in just the last few months. We are at a 14-year peak. And the countries that import the most from Russia and Ukraine (such as Egypt or Indonesia) will bear the brunt of this crisis.

Together, Russia and Ukraine’s exports account for 12% of the world’s traded calories. The two countries account for almost 30 percent of global wheat exports, almost 20 percent of corn exports, and more than 80 percent of the world supply of sunflower oil. However, the compounded effect of embargo and devastation in the two countries will surely exert tremendous influence on the global economic outlook for years to come.

What are the perspectives?

Agriculture was already hurting before February 24^th. Poor harvests caused by extreme weather conditions, continued losses along the production chain, supply chain issues, and abnormal pandemic buying patterns combined to sink global wheat stocks one third lower than the five-year average. Reserves, in other words, are low – and will be significantly lower.

We need to be realistic about the coming months and years. Corn (where Ukraine accounts for 13% of global exports) and wheat will be severely hit by the war and its aftermath. This will compound all the pre-existing factors (transportation costs, supply chain slowdown, continuing weather disruptions, energy costs), none of which will trend down. Fertilizer prices have also gone up exponentially, and Russia – the largest exporter – has banned fertilizer exports at the beginning of March. The effects will be ultimately reflected in the cost of raw materials.

Ukraine and Russia have all but banned grains exports – either for security reasons or to protect internal needs. On top of this, the last harvests collected in Ukraine are now sitting in bins where ventilation and temperature controls have been affected by power cuts.

Source: World Bank, March 2022

At the end of February, World Bank data already showed upward movement for nearly all categories; whatever was not trending up at that time is catching up fast. The last time things looked like this, experts warn, was in 2008-2009 – and social unrest followed around the world, to serious global consequences.

However, the perspective is not catastrophic and there is room to conserve profitability. The essential is to intervene with fast, targeted action that favors smart optimization, localization, and long-term planning.

What can feed producers do?

 Most feed producers will be caught in the middle of all rising costs, from raw materials to transport and energy. Where, then, can they look for shelter when the storm hits?

Optimize feed costs without losing performance

One of the first things feed producers will focus on will be cutting down feed costs. At this point, it is essential that this basic optimization does not impact animal health and performance. Here is what should be kept in mind.

Preserve feed material and feed quality

Whatever raw materials you choose to use, minimizing losses and maintaining quality should be the first step. Losses caused by storage are often the easiest to mitigate.

Quick intervention #1: Use mold inhibitors and mitigate the impact of mycotoxins

Compensate for lost nutrients (protein content, digestibility)

Freight costs will continue to cause pressure on transported raw materials, driving producers to local/regional options. When you replace one feed ingredient with a cheaper one, the first effects will be on the active principle and on the digestibility of the feed. Often something you are taking out of the diet cannot be replaced 1:1.

Quick intervention #2: Maximize the use of enzymes to ensure high feed digestibility; for poultry, pigments can replace corn-derived coloration (to control color variability)

Compensate for stress caused by diet changes

Adjusting the feed composition doesn’t only have effects on paper.

Even if you choose the best replacements, adjust the balance, compensate for loss of digestibility and optimize everything in every possible way, one thing remains:

The animal receives a new diet.

New diets are textbook stressors. But sometimes the nutritionist or the producer is so stressed that it is easy to overlook the stress placed inside the animal. Since animal efficiency is key for productivity, it is essential that the effects of diet stress are mitigated for the animal.

Quick intervention #3: Precautionary use of gut-health mitigating additives; also consider palatable feed materials and taste enhancers

Optimize production costs without losing quality

To optimize costs on the production floor, there are three essential areas where feed producers can act:

• Saving on energy costs and reducing the carbon footprint
• Reducing losses on the production floor
• Increasing throughput without increasing manpower

To answer these challenges, there are solutions that can operate individually. More importantly in such times, there are products that can impact all three areas without negatively influencing the quality of output. One such solution, for instance, can decrease energy costs, increase throughput and pellet quality, and reduce fines.

Quick intervention #4: Choose a solution that satisfies 3/3 of your issues

Conclusion

Climate change will continue to wreak havoc on the predictability of harvests. Freight costs are projected to keep rising. And the costs of war and (hopefully) reconstruction will take a toll on the cost of living and cost of doing business around the world, for years to come.

In the storm that has already started, it is unwise to take shelter for a while and hope for good weather soon. Cutting down on ingredients here and additives there won’t keep profitability high in the long run. Feed producers must look at all aspects – from feed storage and composition to process improvement – and consider holistic measures that protect animals and profitability at the same time.

Poultry producers worldwide use natural carotenoids in feed formulations for laying hens and pigmented broilers. With European Union regulation restricting the use of apoester to 5 ppm in animal feed, it is more relevant than ever for poultry producers that safe, natural alternatives exist. Regulatory limits for natural xanthophylls, in contrast, are set at up to 80 ppm in complete feed.  

At EW Nutrition, natural xanthophyll production is a specialized and standardized process that includes quality assurance at all stages, from planting to harvesting, extraction, and saponification. The outcome is uniform and very stable products that deliver consistent, reliable results.   

How to choose and handle pigmentation products for maximum performance? 

• Choose a trusted pigment brand with verifiable quality controls and carotenoid handling expertise 
• Use commercially available products in their original, unopened bags 
• Use fresh products that are within their shelf-life period 
• Suspend products that do not fulfill pigmentation levels after opening (e.g., a level that is one third or more below the supplier specification indicates a damaged product) 
• Store products in closed and dark bags with little exposure to oxygen during storage 

EW Nutrition’s Colortek Yellow B pigment for poultry contains ≥ 100 g/kg of natural yellow xanthophylls extracted from the marigold flower (Tagetes erecta spp.). It achieves consistent, uniform, and high-quality coloration for egg yolk and broiler skin, as attested by independent certifications FAMI QS, ISO 14000, and ISO 9001.  

A trial was designed to compare the stability of natural Colortek Yellow B and a synthetic apoester product (Carophyll Yellow, DSM [Batch L 1954]) in a premix under challenge conditions (high level of choline chloride). As shown in Figure 1, Colortek Yellow B outperformed the apoester, offering superior stability. 

Figure 1. Stability in vitamin mineral premix (12.5% choline chloride, closed bag, 30°C, 75% RH) 

These results underscore that Colortek Yellow B offers the stability poultry producers require for a successful pigmentation program. As poultry producers adopt natural carotenoid alternatives, they can be assured that specialized and standardized production processes and strict quality controls guarantee these products’ reliable performance. 

Salmonellosis is a zoonosis, meaning that it can be easily transferred from animals to humans. The transfer can occur via different routes:

• Direct contact with an infected animal
• Handling or consuming contaminated animal products such as eggs or raw meat from pigs, turkeys, and chicken
• Contact with infected vectors (insects or pets) or contaminated equipment

Frozen or raw chicken products, as well as the eggs of backyard hens, are the most frequent causes of animal-mediated Salmonella infections in humans. The following graphic shows a clear relationship between the occurrence of Salmonella in layer flocks and the event of disease in humans:

The impact of Salmonella on poultry depends on the bird’s age

Within the poultry flock, there are two ways of spreading: the fecal-oral way (horizontal infection) or the infection of the progeny in the egg (vertical infection). The effects of the disease depend on the age of the birds: the younger the animals, the more severe the impact.

If the brood eggs already carry salmonellae, the hatchability dwindles. During their first month of life, infected chicks show ruffled downs and higher temperatures. Diarrhea leads to fluid losses and frequently to the chicks’ death.

Adult animals usually do not die from Salmonellosis; often, the infection remains unnoticed. During a substantial acute salmonella outbreak, the animals show weakness and diarrhea. They lose weight, resulting in decreased egg production in layers and worse growth performance in broilers. The birds need more water to compensate for the fluid losses, and their crowns and jowls appear pale.

Salmonella protects itself through an intelligent infection style

Salmonellae have developed a clever way to protect themselves. After they arrive in the gut, they attach to the epithelial cells and form small molecular “syringes” to inject divers substances into the gut cells (Type-3-injection system). These signaling substances make the gut cells bulge their membranes and enclose the bacterium. Finally, the manipulated gut cell absorbs the Salmonella, the host “allows” the bacterium to enter, and it can proliferate in the gut cells (Fischer, 2018).

When an antibiotic is attacking the bacterium, Salmonellae stop their cell division. Since many antibiotics are only effective against bacteria during cell division and growth, Salmonellae survive the attack by staying as dormant variants or persisters until the treatment stops (Fischer, 2018).

Salmonellae – a big “family”

The genus of Salmonella consists of more than 2600 serovars (Ranieri et al., 2015), of which less than 100 are relevant for humans (CDC, 2020). More than 1500 serovars belong to the Salmonella enterica subspecies that colonize the intestinal tract of warm-blooded animals. These serovars are responsible for 99 % of salmonella infections (Mendes Maciel et al., 2017). The main serovars relevant for poultry are S. Gallinarum and S. Pullorum, but also S. Enteritidis, Typhimurium, and in recent years, S. Kentucky, S. Heidelberg, S. Livingstone, and S. Mbandaka (Guillén et al., 2020).

The zoonosis Salmonellosis must be controlled

Several Salmonella serovars are critical for animals and humans. Since more than 91,000 salmonellosis cases are reported for Europe and more than 1.35 million for the USA every year (EFSA, 2022; FDA, 2020), their spread must be prevented by all means. Governments have enacted some laws to curtail this disease. The EU, for example, implemented extended control programs for zoonotic diseases, with Salmonella set as a priority. These programs include the provision of scientific advice, targets for reducing Salmonella in poultry flocks, and restrictions on the trade of products from infected flocks.

For farmers and vets, this means the obligation to notify the occurrence of the disease to the authorities. Depending on the country, it also entails compulsory vaccination and the documentation of hygienic measures. In the EU, due to the risk of developing resistances, the EFSA recommends limiting the use of antimicrobials to individual cases, e.g., to prevent inordinate suffering of animals.

Prevention of Salmonella infection is the key

The best strategy for salmonella control is prevention based on three key points (Visscher, 2014):

• Preventing the introduction of Salmonella into the farm/flock through effective hygiene measures
• Preventing the spread of the pathogens within a flock/farm
• Prophylactic measures to recover immune resistance of the animals against Salmonella infection

For this purpose, the following steps are requested/recommended:

1.    Keeping the litter dry

The use of well-absorptive material such as wood shavings, straw pellets, or straw granulates and regular removal of the used litter is recommended. The animals must be controlled for diarrhea to avoid wet droppings. The water supply must be adequate; an excessive water supply wets the litter.

2.    Providing a clean environment

To keep the poultry house clean, broken eggs and dead animals (potential sources of infection) must be removed. In general, the houses should be cleaned and disinfected before every restocking.

Clean feed and water are essential; therefore, feed should not be stored outside but be kept dry and protected from pests and rodents. The feeding of the animals should take place inside to avoid contamination by wild birds. Concerning the water for drinking, the flow rate must be high enough to provide the birds with sufficient water but not too high that the floor gets wet. The troughs must be clean from droppings.

3.    Limiting contacts

To limit the spread of Salmonella, only a restricted number of persons can have access to the flocks. They must wear clothes, and instruments should be exclusively used for the respective poultry house.

Knowing the optimal growth conditions for Salmonella facilitates control

Salmonellae are a genus in the family of Enterobacteriaceae. They are gram-negative, rod-shaped (size: approx. 2 µm), glucose-fermenting facultative anaerobes that are motile due to peritrichous flagella. Since Salmonellae do not form spores, they can be easily destroyed by heating them to 60°C for 15-20 min (Forsythe, 2001), especially in food/feed with higher water content.

For the storage of food, Bell and Kyriakis (2002) found that most serovars of Salmonella will not grow at temperatures lower than 7°C and a pH lower than 4.5. Wessels et al. (2021) showed optimal growth conditions for Salmonella: temperatures between 5 and 46°C (optimum 38°C), a water activity of 0.94-0.99, and a pH of 3.8-9.5.

A high fat content in the feed or food increases the likelihood of infection with Salmonella because the fat protects the bacteria during the passage through the stomach. Doses of 10 to 100 Salmonella cells can already pose a severe risk (University of Georgia, 2015).

Natural alternatives to antibiotics: effective Salmonella control?

To reduce the incidence of Salmonella while simultaneously lowering the use of antibiotics in animal production, there are different possibilities. On the one hand, veterinary medicine offers vaccines. On the other hand, the feed industry provides additives that strengthen the immune system, improve gut health, or support the animals in another manner. Other than pro- and prebiotics, the main active ingredient categories for such additives are organic acids and phy­tomolecules.

Organic acids worsen the conditions for Salmonella

Already in ancient Egypt, the method of fermentation and the generated acids have been used for the conservation of food (Ohmomo et al., 2002). Nowadays, it is a standard tool to protect feed  (silage) and food from spoilage. Also for animals, organic acids added to the feed or the water have proven helpful against pathogens. These modes of action can be combined against Salmonella: reducing the pathogen load in the feed to limit the intake of bacteria and fighting against these pathogens in the animal.

Organic acids reduce Salmonella in feed materials

In general, the antimicrobial activity of organic acids in feed is based on lowering the pH (Pearlin et al., 2019). pH-sensitive bacteria such as Salmonella minimize their proliferation at a pH <5. Additionally, the organic acids attack bacteria directly. The acid’s undissociated and more lipophilic form penetrates the bacterial cell membrane. At the neutral pH within the cell, the acid dissociates, releases protons, and lowers the pH, leading to the impediment of metabolic processes in the cell. The cell spends a lot of energy trying to get the pH back to neutral (Mroz et al., 2006). Additionally, the anions become toxic for the cell metabolites and disrupt the membrane (Russel, 1992).

What do organic acids do in the bird?

According to Hernández and co-workers (2006) and Thompson and Hinton (1997), the addition of organic acids to the feed does not change the pH in the various digestive tract segments. Still, literature shows a clear reduction of Salmonella in the gut or litter when using propionic or/and formic acid (McHan and Emmett, 1992; Hinton and Linton, 1988; Humphrey & Lanning, 1988). A likely mode of action is described by Van Immerseel et al. (2004). He asserts that SCFAs such as propionic and formic acid as well as MCFAs can inhibit Salmonella’s penetration of the intestinal epithelium and, therefore, can control these invasive phenotypes of Salmonella (S. Typhimurium and S. Enteritidis).

Different acids show different efficacy

Depending on the acid, the efficacy against Salmonella varies (see figure 3). Formic acid shows the highest effect, followed by fumaric acid. Then, lactic, butyric, and citric acid follow, showing lower efficacy.

Trials prove the efficacy of organic acids

An in-vitro trial was conducted at a commercial research facility in the US to test the efficacy of Acidomix AFL, a liquid mixture of propionic and formic acid, against Salmonella. The bacterial strain used in these studies was nalidixic acid-resistant Salmonella typhimurium. The bacteria were maintained in broth cultures of tryptic soy broth.

They were added to 5 g of dry feed in a 50 ml tube to a final concentration of 40,000 CFU/g. Next, Acidomix AFL was added to the desired inclusion rate, and the samples were incubated at room temperature. After 18 to 72 hours of incubation, viable bacteria were counted using the plate count method.

Results: As shown in figure 4, the trial found that at an inclusion rate of 2.0 %, Salmonella inhibition was nearly 100 %. Already at a 0.4 % inclusion rate, Salmonella could be reduced by 45-60 %, showing a clear dose dependency.

Phytomolecules combat Salmonella through complex modes of action

Plants produce phytogenic substances to protect themselves from molds, yeasts, and bacteria, among others. After several purification steps, these phy­tomolecules can be used to fight Salmonella in poultry. They work through different modes of action, from attacking the cell wall (terpenoids and phenols) to influencing the genetic material of the pathogenic cells or changing the whole morphology of the cell.

Due to the different modes of action, it was long thought that there would be no resistance development. Still, Khan et al. (2009) found some microorganisms such as multidrug-resistant E. coli, Klebsiella pneumoniae, S. aureus, Enterococcus faecalis, Pseudomonas aeruginosa, and Salmonella typhimurium can show a certain – perhaps natural – resistance to some components of herbal medicines.

Gram-negative bacteria such as Salmonella are usually less attackable by phytomolecules because the cell wall only allows small hydrophilic solutes to pass; however, phy­tomolecules are hydrophobic. However, mixing the phytomolecules with an emulsifier facilitates the invasion into the cell. Their efficacy depends on their chemical composition. It is also decisive if single substances or blends (possible positive or negative synergies) are used.

The best-clarified mode of action is the one of thymol and carvacrol, the major components of the oils of thyme and oregano. They can get into the bacterial membrane and disrupt its integrity. The permeability of the cell membrane for ions and other small molecules such as ATP increases, decreasing the electrochemical gradient above the cell membrane and the loss of energy equivalents.

Trials show the efficacy of phy­tomolecules against Salmonella

Two different phytogenic compositions were tested for their efficacy against Salmonella.

Trial 1: Blend of phy­tomolecules and organic acids shows best results in an in-vitro assay

To evaluate its potential as a tool for antibiotic reduction, a trial was conducted to test the antimicrobial properties of Activo Liquid, a mixture of selected phy­tomolecules and an organic acid designed for application in water. The laboratory test was carried out at the Veterinary Diagnosis Department of Kasetsart University in Thailand. Standardized suspensions [1×10⁴ CFU/ml] of three poultry-relevant Salmonella strains were incubated in LB medium, either without or with Activo Liquid. The tests were run at concentrations of 0.05%; 0.1%; 0.2% and 0.4%. After incubation at 37°C for 6-7 hours, serial dilutions of the cell suspensions were transferred onto LB agar plates and incubated for 18-22h at 37°C. Subsequently, colonies (CFU/ml) were determined.

Results: Activo Liquid was found to be growth-inhibiting to all Salmonella strains from a concentration of 0.1% onwards. At 0.2%, Activo Liquid already exhibited bactericidal efficacy against all tested Salmonella isolates, which was confirmed at a concentration of 0.4%.

Trial 2: Blend of nature-identical phy­tomolecules inhibits Salmonella

On Mueller Hinton agar plates where Salmonella enterica were spread uniformly, small disks containing 0 (control, only methanol), 1, 5, and 10 µl of Ventar D were placed and incubated at 37 °C for 16 hours. The presence of clearing zones indicates antimicrobial activity.

Additionally, a motility test was performed in tubes with a motility test medium containing 0 (control) and 750 µL Ventar D. For this purpose, one colony of Salmonella enterica grown on the agar was stuck in the middle of the medium and incubated at 37 °C for 12-16 hours. Growth can be visualized through the formation of red color.

Result: Ventar D inhibited S. enterica in a dose-dependent manner. Clearing zones were visible within the lowest tested concentration. At its inhibitory concentration, Ventar D suppressed S. enterica motility (figures 5 and 6).

Let’s fight Salmonella through effective and sustainable natural tools

The zoonosis Salmonella generates high costs in the poultry industry. As Salmonellosis can be transferred to humans, it must be kept under control by all means. Antibiotics are one tool to fight Salmonella, but they have their “side effects”: they are no longer well respected by the consumer, and, even more critically, they create resistance. To help keep antibiotics effective, poultry producers seek to use effective but not resistance-creating natural solutions against Salmonella.

As shown with the reviewed trials, organic acids and phytomolecules are highly active against diverse Salmonella serovars. Accordingly, feed additives based on these active ingredients offer effective tools for controlling Salmonella in poultry while also contributing to the overarching aim of reducing antibiotic use in poultry production.

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