Optimizing Digestive Efficiency: The Key to Resilient Piglets

In Brief
 
  • Decreases in performance in the early life of a piglet can compromise performance in the growing and finishing phases.
  • A resilient piglet is well-equipped to withstand future challenges and better enabled to achieve its genetic potential.
  • Two strategies are key to ensuring resilient piglets: improving pre-absorptive nutrient uptake and optimizing post-absorptive nutrient utilization. 

After successfully weaning a piglet and conquering the immediate post-weaning challenges, the next most important task for the producer is to build a resilient pig that is well equipped to combat future challenges. The importance of building resilience in piglets post-weaning is demonstrated clearly in work by Brossard et al. (2006) which indicates that pig weight at 65 days of age explains 35% of the average daily gain observed between day 65 and reaching 110 kg of body weight. The key message is that any decrease in performance in the early stages of life compromises performance in the growing and finishing phases.

What is resilience?

But what does resilience really mean? Resilience was defined by Colditz and Hine (2016) as “the capacity of the animal to be minimally affected by a disturbance or to rapidly return to the physiological, behavioral, cognitive, health, affective and production states that pertained before exposure to a disturbance.” All the challenges that a pig encounters detract the pig from reaching their inherent genetic potential so their reaction to these challenges dictate the extent of this deviation. 

Swine geneticists have incorporated the concept of resilience into their breeding programs and demonstrated the clear advantages in performance that can arise from having resilient pigs. One model used to evaluate resilience is the concept of residual feed intake (RFI). Residual feed intake can be explained as the difference between the observed and expected feed intake based on a pig’s average daily gain and/or backfat deposition.  Animals with high RFI use more nutrients for a given level of performance than animals that have a low RFI.  Low RFI animals are therefore more efficient at extracting and/or utilizing nutrients, and methods to optimize this efficiency are an integral aspect of supporting resilience.

Another key component in understanding the role of resilience in piglets is the degree to which the challenge impacts the pig, and the length of time needed for the pig to recover from the challenge. The recovery period can be considered as the resilience period. The level of recovery in performance is related to the health, immune competency and gut functionality of the piglets and is why getting these aspects right is so important. The particularly important role of the immune system in resilience has been shown in a number of publications, such as a paper by Sauerwein (2005), that have measured the relationship between haptoglobin (an acute phase protein that reflects sub-clinical inflammation) level and performance. As haptoglobin blood level increases, average daily gain decreases.

It is important to recognise that the immune system requires a different suite and supply of these nutrients, especially amino acids, to what is needed for lean muscle growth and that feeding diets to support lean muscle accretion may not adequately supply the correct proportion of nutrients to support immune optimisation. For example, the amino acids phenylalanine, tryptophan and threonine are needed in much higher proportion for acute phase protein synthesis than skeletal muscle deposition (Klasing and Iseri, 2013). Similarly, when animals are challenged with unsanitary conditions (requiring an upregulated immune response), the requirement ratio between tryptophan and lysine is altered with pigs in unsanitary conditions requiring more tryptophan to maintain acceptable performance (Le Floc’h, 2009) and in addition overall nitrogen digestibility is decreased in unsanitary conditions (Noorman, 2002).  Decreasing nitrogen digestibility and nitrogen retention efficiency can lead to increases in protein substrate availability in the hindgut for pathogen growth, further challenging the immune system of the pig.

Therefore, the key aspects to supporting resilience in pigs is to ensure:

        1) the optimal extraction of nutrients from the feed (optimum nutrient digestive efficiency –
        the pre-absorptive component), and

         2) the appropriate allocation of nutrients to maintenance and production (the post-
        absorptive component). 

These concepts are outlined in Figure 1.

Figure 1. Mechanisms for Supporting Resilience 

Improving pre-absorptive nutrient uptake

The key element to address in the pre-absorptive phase of nutrient utilization is to ensure that feed digestibility is maximized so that nutrients are unlocked and the pig can extract maximum value from its feed. Digestibility can be maximized via two main mechanisms, 1) ensuring fiber, protein and starch are fully utilized and 2) removing bacterial cell debris (such as peptidoglycans) from the intestinal surface so that the digested nutrients are available for absorption. 

Ensure that feed digestibility is maximized so that the pig can extract maximum value from its feed.

Post-weaning piglet diets can include a range of plant-based ingredients containing many different types of non-starch polysaccharides (NSPs) contributing indigestible components such as arabinoxylans, glucans, mannans and galactans and impacting diet viscosity and digestibility of nutrients. The endogenous enzymes in the pig are unable to fully digest these NSP components. The use of targeted exogenous carbohydrases such as xylanases, β-glucanases, β-mannanases, and amylases have been shown to improve the net energy of the diet by cleaving NSP fractions into more readily fermentable components (Kiare et. al., 2013) and thereby facilitating more flexibility in the choice and sourcing of feed ingredients for pigs. Improving fiber digestion through use of exogenous enzymes has also been shown to modulate the microbial ecology and stimulate fermentation which can improve gastrointestinal health through the stimulatory effects of short chain fatty acids, especially butyrate (Kerr and Shurson, 2013; Zhao et. al., 2019).

In addition to maximizing net energy extraction, ensuring full utilization of the amino acids in the diet, is also essential to enable the piglet to achieve its genetic potential. Decreasing the undigestible crude protein content of feed and avoiding protein fermentation in the hindgut are important aspects of supporting growth and resilience. While protein sources such as soybean meal, peas and sunflower meal are effective ingredients for supplying amino acids, they also contain significant amounts of cell wall materials consisting of xyloglucans and pectins. These compounds can contribute to an increased viscosity of the digesta preventing effective amino acid utilization and need a combination of enzymes to assist in their breakdown. Supplementing piglet diets with a mixture of enzymes including beta-glucanases and endo-pectinases resulted in an increase in daily weight gain of up to 7% (Schurz and Richter, 2002). Furthermore, Blanco-Perez et al. (2021) have identified that pectins can have indirect and direct beneficial effects on immune modulation and therefore pectin release from raw materials through enzyme use may have positive health benefits for the pig.

When bacteria die, the resulting cell wall debris, which is rich in peptidoglycans, can impair nutrient absorption from the intestinal surface (van Immerseel et al., 2020).  Peptidoglycans can be cleaved by muramidase, resulting in formation of muramyl dipeptide (MDP). The MDP can be recognized by epithelial cell receptors (NOD-2) and the NOD-2 receptors play a crucial role in supporting barrier protection and surveillance of the cell wall (Constans, 2005). Consequently, with a proper functioning cell wall, absorption of nutrients can be maximized.  A meta-analysis of the effect of including muramidase in piglet diets for 42 days showed that average daily gain was improved by 7% and feed conversion efficiency by 6% (DSM, 2020).

Optimizing post-absorptive nutrient utilization

Supporting resilience from the post-absorptive perspective requires the most effective transfer of nutrients to productive purposes such as lean muscle deposition, with limited diversion of nutrients to maintenance and unproductive inflammatory responses. Strategies to reduce the inflammatory processes, such as developing immune competency and gut functionality should be continued in this phase.  As carbohydrates supply approximately 60-70% of the net energy needs of the piglet, a major contributor to resilience is centered on fiber nutrition and its optimized use.  In addition to the use of enzymes to assist with release of nutrients as required in the pre-absorptive phase, use of carbohydrases also play a pivotal role in improving the hindgut fermentation of dietary fiber components, significantly unlocking energy reserves. During hindgut fermentation, production of short chain fatty acids such as butyric acid will also positively influence the growth of colonocytes.  As there are many different ingredients used in piglet feed and they contain many types and concentrations of fiber, it is imperative that the right enzymes are matched to the ingredients. The recent development of near infrared reflectance spectroscopy to predict NSP composition and starch digestibility profiles (Nieto-Ortega et al., 2022) can assist in optimizing which exogenous enzymes to apply.

In addition to the major nutrients of energy and amino acids, supporting resilience also relies on accurate mineral nutrition, including phosphorous. Reducing the negative effects of phytate on nutrient binding can increase mineral availability.  Phytase has been shown to have additional effects on animal performance, over and above the phosphorus effect (Lu et al., 2019), at the post-absorptive level.  A further effect of phytase supplementation is the release of myo-inositol (the core of phytic acid).  A key function of myo-inositol is in stimulation of glucose uptake and glucose uptake has been proposed as a rate limiting step for muscle glycogen synthesis so provision of extra myo-inositol may enhance muscle growth (Lu et al., 2019).

Conclusion

In summary, supporting resilience through optimizing gastrointestinal functionality relies on addressing both the pre-and post-absorptive factors influencing nutrient absorption and utilization. Clearing bacterial cell debris in the gut and use of enzymes to increase digestibility of fiber, protein and starch are important tools in optimizing the pre-absorptive digestive processes.  Effective incorporation into lean deposition of the energy from fibre and the minerals in the feed are central to the post-absorptive processes influencing pig performance potential. Supporting resilience in piglets is key to maximizing lifetime performance and profitability of the pig and supporting the pig in reaching its genetic potential.  

References

Brossard, L., van Milgen, J., Lannuzel, P.Y., Bertinotti, R. and Rivest, J., 2006, January. Analyse des relations entre croissance et ingestion à partir de cinétiques individuelles: implications dans la définition de profils animaux pour la modélisation. In 38. Journées de la Recherche Porcine. ITP.

Colditz, I.G. and Hine, B.C., 2016. Resilience in farm animals: biology, management, breeding and implications for animal welfare. Animal Production Science, 56(12), pp.1961-1983.

Sauerwein, H., Schmitz, S. and Hiss, S., 2005. The acute phase protein haptoglobin and its relation to oxidative status in piglets undergoing weaning-induced stress. Redox Report, 10(6), pp.295-302.

Klasing, K.C. and Iseri, V.J., 2013. Recent advances in understanding the interactions between nutrients and immunity in farm animals. Energy and protein metabolism and nutrition in sustainable animal production, pp.353-359.

Le Floc'H, N., Lebellego, L., Matte, J.J., Melchior, D. and Sève, B., 2009. The effect of sanitary status degradation and dietary tryptophan content on growth rate and tryptophan metabolism in weaning pigs. Journal of Animal Science, 87(5), pp.1686-1694.

Noorman L., de Vries S., Gilbert M., Bart van der Hee G., Gerrits W., 2022. Low sanitary housing conditions reduce ileal N digestibility and enhance the production of protein-derived metabolites in piglets. 15th International Symposium on Digestive Physiology of Pigs, Rotterdam, the Netherlands, pp. 145-156.

Kerr, B.J. and Shurson, G.C., 2013. Strategies to improve fiber utilization in swine. Journal of Animal Science and Biotechnology, 4(1), pp.1-12.

Zhao, J., Bai, Y., Tao, S., Zhang, G., Wang, J., Liu, L. and Zhang, S., 2019. Fiber-rich foods affected gut bacterial community and short-chain fatty acids production in pig model. Journal of Functional Foods, 57, pp.266-274.

Richter, G., Heller, E., Schurz, M. and Arnhold, W., Wirksamkeit NSP-hydrolysierender Enzyme beim Ferkel. Vitamine und Zusatzstoffe in der Ernährung von Mensch und Tier, p.438.

Blanco-Pérez, F., Steigerwald, H., Schülke, S., Vieths, S., Toda, M. and Scheurer, S., 2021. The dietary fiber pectin: Health benefits and potential for the treatment of allergies by modulation of gut microbiota. Current allergy and asthma reports, 21(10), pp.1-19.

Constans, A., 2005. Giving a nod2 the right target: the bacteria-sensing molecule contributes to innate immunity, and mysteriously, to Crohn disease. The scientist, 19(3), pp.24-26.

Nieto-Ortega, S., Olabarrieta, I., Saitua, E., Arana, G., Foti, G. and Melado-Herreros, Á., 2022. Improvement of oil valorization extracted from fish by-products using a handheld near infrared spectrometer coupled with chemometrics. Foods, 11(8), p.1092.

Lu, H., Cowieson, A.J., Wilson, J.W., Ajuwon, K.M. and Adeola, O., 2019. Extra-phosphoric effects of super dosing phytase on growth performance of pigs is not solely due to release of myo-inositol. Journal of Animal Science, 97(9), pp.3898-3906.

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About the Author

Neil Gannon - Global Swine Technical Manager

Dr. Gannon is an Australian with a Bachelor of Agricultural Science (Honours) and a PhD in pig nutrition from the University of Sydney, Australia. Early in his career, Dr. Gannon worked as a research scientist for university and government organisations in the USA and Australia before moving to the commercial sector in a pig technical and nutrition role with the largest feed miller in Australia. After 10 years, Dr. Gannon started his own nutrition and research consultancy and had a part time appointment as a senior lecturer at the University of Queensland, Australia. In 2011, Dr Gannon joined BIOMIN and prior to the acquisition of BIOMIN by DSM in 2021, Dr. Gannon was the Regional Product Manager for Gut Performance in Asia. At DSM, Dr. Gannon continues his technical support of customers and sales colleagues and research interests as Global Swine Technical Manager.

Laurent ROGER, Swine Marketing Manager EMEA

Laurent, a French national, holds a master’s degree in Animal Biology and Physiology from the Pierre and Marie Curie University, in Paris.

He brings more than 20 years of experience in the field of Product Management and nutrition with a focus on Swine. Starting as a Swine Technical Manager evolving to a Swine Department Manager, and global marketing and business maneger, working in an international environment.

He participated to different scientific publications and global projects focusing on health, nutrition and welfare.

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