Phytomolecules: Sustainability And Efficiency In Pig Production

Conference Report
By M. Rosenthal, Global Application Manager Swine, EW Nutrition GmbH

Sustainability is essential for the long-term survival of our planet. In pig production, sustainability involves maintaining economically viable outputs while simultaneously safeguarding animal health and welfare and minimizing environmental impact. The goal is to produce pork that is profitable, ethical, and has a minimal ecological footprint.

Phytomolecules, the bioactive constituents of plant-derived essential oils, play a promising role in advancing this goal. With multifunctional gut health benefits including antimicrobial, anti-inflammatory, antioxidant, and digestive-supportive properties, phytomolecules help maintain gut health and reduce the need for antibiotics. By improving feed efficiency, enhancing resilience, and supporting intestinal integrity, phytomolecules contribute to both sustainability and efficiency in pig production systems.

Targeting sustainability in pig production

Achieving sustainability in pig production requires a balanced approach that considers three key perspectives: those of the producer, the pig, and the environment.
For the producer, sustainable pig production must be profitable to ensure the long-term viability of the industry. This includes factors such as efficient feed conversion, optimized production practices, and fair market prices.

Another aspect is the maintenance of animal health and well-being, which is essential for optimal pig performance and can be achieved by providing appropriate housing, nutrition, and veterinary care, as well as minimizing stress and disease.

From an environmental perspective, minimizing negative impacts, such as greenhouse gas emissions, water pollution, and land degradation, is a key objective. Various strategies, such as improved manure management, efficient nutrient utilization, reuse of farm resources like manure and water, and the use of by-products from other industries as feed ingredients, can be applied.

Strategy for efficient pig production

Historically, pig production has relied heavily on the use of antibiotics to control enteric pathogens, promote gut health, and enhance growth. While effective in the short term, this practice led to unintended consequences, including the emergence of antimicrobial resistance (amr), disruption of microbiota across multiple organ systems, difficulties in manure management, and environmental contamination.

These outcomes triggered societal concern, regulatory interventions, and economic pressure, prompting a shift away from routine antibiotic use. The industry now faces increasing expectations for environmentally responsible practices, reduced dependence on antibiotics, and cost-effective, sustainable solutions.
Achieving both efficiency and sustainability in pig production requires a holistic, system-wide approach that includes an innovative, solution-oriented mindset, optimized management practices, and the adoption of effective gut health antibiotic alternatives.

The foundation of efficiency the gut

The pigs gastrointestinal tract is the largest and most vulnerable interface between the pig and its external environment. It is a highly organized ecosystem comprised of epithelial cells, the mucosal immune system, and a diverse microbiome consisting of both beneficial commensal microbes and potentially harmful pathogens.
The functions of the gut include nutrient absorption, chemosensing of nutrients and other compounds, immune defence, and balancing the highly diverse microbiome within this complex environment (Furness et al. , 2013). Disruption of this ecosystems homeostasis can impair not only gut function and health but also negatively affect the overall well-being and growth efficiency of the pig.

When evaluating antibiotic alternatives to support this ecosystems homeostasis in the face of challenges, considerations include safety for humans, animals, and the environment, cost-effectiveness, antimicrobial efficacy, the ability to increase nutrient availability, and to modulate immune activation and inflammation.

Functional feed additives commonly utilized in pig nutrition, alone or in combination, include organic acids, probiotics, immunoglobulins, medium-chain fatty acids, and phytomolecules.

Phytomolecules: supporting gut health and performance

Phytomolecules are the bioactive components of plant-derived essential oils. Due to the variability in phytomolecule content and the presence of volatile and astringent components in essential oil extracts, utilizing commercial phytomolecule products is recommended. Proprietary formulations utilize encapsulation or matrix technology to protect the phytomolecules from damage or loss during storage, processing, and passage through the stomach.

Extensive research in humans and animals has identified phytomolecules as having antimicrobial, anti-inflammatory, antioxidative, and coccidiostatic properties. They enhance digestibility and immunity, promote gut health through differential modulation of bacterial populations, and reduce inflammation and oxidative stress (Brenes et al., 2010; Puvaca et al. , 2013; Chitprasert et al., 2014). Phytomolecules most researched and utilized in pig feed additives to date include terpenes (e. G., carvacrol and thymol) and phenylpropenes (e.g., cinnamaldehyde and eugenol).

1. Direct antimicrobial activity of phytomolecules

Phytomolecules such as carvacrol and thymol provide broad-spectrum antimicrobial activities against Gram- and Gram+ bacteria, fungi, and yeast and are regarded as promising alternatives to antibiotics in swine production systems (Lambert et al., 2001; Delaquis et al., 2002; Abbaszadeh et al., 2014).

Phytomolecules directly target bacterial cells through multiple mechanisms, with the cell wall and membrane being major sites of action. The lipophilic structure of phytomolecules enables their entry through bacterial membranes among the fatty acid chains, causing the cell wall and membranes to expand and become more fluid. This damage collapses the cell wall and cytoplasmic membrane, resulting in the destruction of membrane proteins, the coagulation of the cytoplasm, and a reduction in proton motive force. The result is leakage of vital intracellular contents and death of the bacterial cell (Cox et al., 1998; Faleiro, 2011; Nazzaro et al., 2013; Yap et al., 2014). For example, thymol and carvacrol can damage the outer membrane of Salmonella typhimurium and Escherichia coli o157: h7 (Helander et al., 1998).

A further direct antimicrobial action involves phytomolecules acting as trans-membrane carriers, exchanging a hydroxyl proton for a potassium ion, resulting in dissipation of the ph gradient and electrical potential over the bacterial cytoplasmic membrane. The result is a reduced proton motive force and the depletion of the intracellular adenosine triphosphate (APT) pools. Loss of potassium further inhibits bacterial function as it is needed for the activation of cytoplasmic enzymes to maintain osmotic pressure and regulate intracellular pH. (Wendakoon et al., 1995).

In summary, the primary direct antimicrobial mechanism of action for terpene and phenylpropene phytomolecules is related to their effects on cell walls and cytoplasmic membranes, and energy metabolism of pathogenic bacteria.

2. Indirect antimicrobial activity of phytomolecules

Phytomolecules indirectly impact the physiological functioning and virulence capability of pathogenic bacteria through the interference of quorum-sensing (QS). QS involves pathogenic bacteria producing signaling molecules that are released based on cell numbers. The detection of these molecules regulates pathogen population behavior such as attachment, biofilm formation, and motility, i. e. , virulence (Greenberg, 2003; Joshi et al., 2016).

QS mechanisms require signal synthesis, signal accumulation, and signal detection, providing three opportunities for QS inhibitors to disrupt pathogenic bacteria from causing disease (Czajkowski and Jafra, 2009; Lasarre and Federle, 2013). Eugenol and carvacrol have been extensively studied for their QS inhibition activities (Zhou et al., 2013; Burt et al., 2014).

3. Combinations increase efficacy

Additional antimicrobial effects can be seen when different phytomolecules are combined, and/or applied with other functional additives such as organic acids (Souza et al., 2009; Hulankova and Borilova, 2011). Zhou et al. (2007) reported that carvacrol or thymol in combination with acetic or citric acid had a better efficacy against S. typhimurium when compared to the individual phytomolecule or organic acid. In recent studies, results have shown in vivo efficacy of such synergistic dietary strategies in pigs (Diao et al., 2015; Balasubramanian et al., 2016). The combined inclusion of phytomolecules and organic acids in pig diets before slaughter may hinder Salmonella shedding and seroprevalence (Walia et al., 2017; Noirrit et al., 2016).

4. Phytomolecules are more than antimicrobials

In addition to acting as antimicrobials, phytomolecules enhance production efficiency through multiple complementary mechanisms, including direct anti-inflammatory, antioxidative, digestive, and gut barrier-supportive effects.

Anti-inflammatory effects: Gut inflammation in pigs not only compromises intestinal function and barrier integrity but also has a direct negative impact on growth performance and overall health. Chronic or excessive immune activation diverts energy away from productive processes such as growth and feed efficiency.

Phytomolecules have demonstrated the ability to modulate immune responses by influencing key cell-signalling pathways involved in inflammation. For example, compounds such as cinnamaldehyde and carvacrol can modulate the activity of critical transcription factors, including nuclear factor erythroid 2 2-related factor 2 (Nrf2) and nuclear factor kappa B (NF-κB). Through this dual action, phytomolecules can simultaneously activate antioxidant defences and suppress pro-inflammatory signalling, thereby reducing intestinal inflammation and supporting improved performance outcomes (Krois-mayr et al., 2008; Wondrak et al., 2010; Zou et al., 2016).

Antioxidant effects: oxidative stress is a major biological challenge in modern swine production systems, where high-performance animals are frequently exposed to stressors such as weaning, disease challenges, heat stress, mycotoxin exposure, transport, and overcrowding. These stressors promote the generation of reactive oxygen species (ROS), and when ROS production exceeds the capacity of the pig’s antioxidant defence systems, oxidative stress occurs.

This imbalance can negatively affect growth, immunity, muscle integrity, feed intake, milk yield, and reproductive performance, including increased abortion rates in gestating sows (Zhou et al., 2013; Burt et al., 2014). As a result, there is growing interest in the use of natural antioxidant compounds, particularly phytomolecules, to counteract these detrimental effects. For example, carvacrol and thymol (1:1 ratio) at 100 mg/kg dietary supplementation reduced weaning-associated oxidative stress by decreasing TNF-α mRNA expression in the intestinal mucosa (Wei et al., 2017).

Additionally, carvacrol supplementation in the diets of late gestation and lactating sows under oxidative stress conditions significantly improved piglet performance (Tan et al., 2015).

Digestive function: The gastrointestinal tract functions not only as a site for nutrient absorption but also as a sensory organ. Specialized chemosensors in the gut monitor the concentration and composition of nutrients, playing a crucial role in the regulation of digestive enzyme secretion, gut peptide release, feed intake, and nutrient absorption and metabolism.

Studies in weaner piglets have shown that certain phytomolecules can stimulate the secretion of digestive enzymes and enhance gastrointestinal function (Maenner et al., 2011; Li et al., 2012).

Tight junctions and gut barrier integrity: The intestinal epithelium functions as a highly dynamic and selective barrier, facilitating the absorption of fluids and solutes while preventing the translocation of pathogens and toxins into underlying tissues. This barrier function occurs through intercellular tight junctions. During episodes of mucosal inflammation, the integrity of these junctions can be compromised, leading to increased intestinal permeability, reduced nutrient absorption, and systemic immune activation and inflammation.

Research has shown that phytomolecules can enhance transepithelial electrical resistance and upregulate the expression of tight junction proteins, reducing epithelial permeability and maintaining a functional barrier, even under inflammatory conditions (Yu et al., 2020; Kim and Kim, 2019).

Sustainable efficiency in pig production supported by in-feed phytomolecules

As the pig industry moves away from reliance on in-feed antibiotics, the need for sustainable, efficient, and health-focused production strategies has never been greater. Modern pig production systems must respond to societal expectations, regulatory mandates, and environmental pressures, while still maintaining profitability and high animal welfare standards.

Central to this transformation is a holistic approach-one that includes a shift in mindset among stakeholders, optimized management across all production domains, and the strategic use of effective antibiotic alternatives. The gastrointestinal tract, as the core of nutrient absorption and immune defence, is a critical control point for supporting health and performance.

Phytomolecules and other functional feed additives have demonstrated potential to enhance gut integrity, reduce inflammation, combat oxidative stress, and improve nutrient utilization. While no single solution can fully replace antibiotics, targeted combinations of these compounds have shown the most consistent success in promoting gut health and sustainable performance.

With continued innovation, collaboration, and science-based application of these alternatives, the industry is well-positioned to achieve its goals of profitable, ethical, and ecologically responsible pork production for the future.

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