With an increasing global demand for protein, improving the efficiency of swine production is critical. Feed efficiency represents the efficiency with which pigs utilize dietary energy and nutrients for maintenance, lean gain, and lipid accretion.1 Greater feed efficiency is achieved when productive and healthy animals require less feed or a shorter time to hit market weight goals. Since feed is a key element of pig production, feed efficiency also strongly influences financial returns for a swine operation. 1,2 In this article, we will discuss the importance of maximizing the feed efficiency of pigs in terms of ingredient quality and feed additives that can improve digestibility and have a positive impact on sustainability.
Swine feed costs make up the greatest proportion of all production expenses. To decrease diet cost, alternative ingredients are frequently used in swine diet formulation, although sometimes these alternative ingredients have lower bioavailability which can negatively impact pig performance and feed efficiency.3 For this reason, producers should routinely evaluate their manufacturing processes and the nutritional value of the end-product to ensure adequate performance and a low cost-to-benefit ratio. Soybean meal, dried distillers’ grains with solubles, bakery meal, and meat and bone meal are co-products of pig diets that undergo multistep processing before reaching the final product sold for feed usage and, thus, may often present variable nutrient levels.3 There is a great deal of variation among fats in terms of composition, quality, energy content, and price.4 In addition, oxidation, which degrades unsaturated fatty acids, is a risk factor that can reduce lipid nutritional value and palatability, but either non-specific or no information about the extent of lipid peroxidation which reflects lipid quality is provided for lipid products.4 Pigs fed peroxidized lipids may present changes in their gut epithelial barrier function due to cellular damage, as well as alterations in genes that regulate fatty acid metabolism, both of which have a negative effect on growth performance.5,6
The source of the ingredients and harvest season are other factors that can influence the nutritional value of pig feed ingredients. For example, Lagos & Stein (2017) reported that soybean meal sourced from Brazil and India had the highest concentrations of amino acids, while China’s had the lowest.10 Since grains are variable year to year, their nutritional value, quality, and potential mold/mycotoxin issues are also variable. The challenges with variable alternative ingredients can be mitigated by implementing ingredient specifications with a supplier and staying in touch with purchasing agents, suppliers, and receiving personnel to ensure the manufacturing of high-quality feed.3
Feed additives are defined by The Official Journal of the European Union as substances, microorganisms, or preparations other than feed material and premixtures, which are intentionally added to feed or water to affect the animal favorably in one of many ways including improving the feed characteristics, satisfying the nutritional requirements of the animal, improving the performance or welfare of the animal, particularly by affecting the gastrointestinal flora, and many others.7 Exogenous enzymes are used as feed additives in animal feed to increase the bioavailability and digestibility of nutrients by degrading their complex matrices to help eliminate some anti-nutritional factors, maintain intestinal health, and increase animal performance.8
Emulsifier additives are molecules capable of breaking down large fat droplets into smaller droplets, thus providing extra surface area for lipase and bile salt attachment that support the digestion of fats and fat-soluble nutrients (e.g., some vitamins and carotenoids) and enhance nutrient absorption.9 Emulsifiers are used in pig diets generally as synthetic molecules, lecithins, and lysolecithins. Synthetic emulsifiers are especially beneficial for young animals that have less developed digestive tracts with insufficient bile salts to help emulsify dietary fats. Lysolecithins contain mixtures of phospholipids, lysophospholipids, and triglycerides, which offer emulsifying properties and interact with biological membranes to enhance nutrient absorption by intestinal epithelial cells. A good emulsifier must support all of the steps in fat digestion, while also improving emulsification, increasing the speed of digestion, and facilitating fat or fat-soluble nutrient absorption.
Diet formulation will be more challenging with the push for medication-free feed and the need to improve the costs of feeding and animal performance. Therefore, alternative ingredients will increasingly be introduced at the feed mill. However, it is worth remembering that the least-cost diets are not necessarily the most digestible diets. Maximizing the digestibility of the feed is a key factor in feed efficiency. In addition, animals with greater feed efficiency have a reduced environmental impact and less nitrogen and ammonia excretions into the environment.
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References
1Patience, J. F., Rossoni-Serão, M. C., & Gutiérrez, N. A. (2015). A review of feed efficiency in swine: Biology and application. Journal of Animal Science and Biotechnology, 6(1), 1–9. https://doi.org/10.1186/S40104-015-0031-2/TABLES/4
2Gaines AM, Peterson BA, Mendoza OF. Herd management factors that influence whole herd feed efficiency. In: Patience JF, editor. Feed efficiency in swine. Wageningen: Wageningen Academic Press; 2012. p. 15–39.
3Paulk CB, Stark CR, Dunmire KM. Feed processing technology and quality of feed. In: Chiba LI, editor. Sustainable Swine Nutrition. Hoboken: Willey Blackwell; 2nd ed; 2022. p.429-444.
4Shurson, G. C., Kerr, B. J., & Hanson, A. R. (2015). Evaluating the quality of feed fats and oils and their effects on pig growth performance. Journal of Animal Science and Biotechnology, 6(1), 1–11. https://doi.org/10.1186/S40104-015-0005-4/TABLES/3
5Dibner, J. J., Atwell, C. A., Kitchell, M. L., Shermer, W. D., & Ivey, F. J. (1996). Feeding of oxidized fats to broilers and swine: effects on enterocyte turnover, hepatocyte proliferation and the gut associated lymphoid tissue. Animal Feed Science and Technology, 62(1), 1–13. https://doi.org/10.1016/S0377-8401(96)01000-0
6Liu, P., Chen, C., Kerr, B. J., Weber, T. E., Johnston, L. J., & Shurson, G. C. (2014). Influence of thermally oxidized vegetable oils and animal fats on growth performance, liver gene expression, and liver and serum cholesterol and triglycerides in young pigs. Journal of Animal Science, 92(7), 2960–2970. https://doi.org/10.2527/JAS.2012-5709
7Pluske, J. R. (2013). Feed- and feed additives-related aspects of gut health and development in weanling pigs. Journal of Animal Science and Biotechnology, 4(1), 1–7. https://doi.org/10.1186/2049-1891-4-1/TABLES/1
8Velázquez-De Lucio, B. S., Hernández-Domínguez, E. M., Villa-García, M., Díaz-Godínez, G., Mandujano-Gonzalez, V., Mendoza-Mendoza, B., & Álvarez-Cervantes, J. (2021). Exogenous Enzymes as Zootechnical Additives in Animal Feed: A Review. Catalysts 2021, Vol. 11, Page 851, 11(7), 851. https://doi.org/10.3390/CATAL11070851
9Wealleans, A. L., Bierinckx, K., & di Benedetto, M. (2021). Fats and oils in pig nutrition: Factors affecting digestion and utilization. Animal Feed Science and Technology, 277, 114950. https://doi.org/10.1016/J.ANIFEEDSCI.2021.114950
10Lagos, L. v., & Stein, H. H. (2017). Chemical composition and amino acid digestibility of soybean meal produced in the United States, China, Argentina, Brazil, or India. Journal of Animal Science, 95(4), 1626–1636. https://doi.org/10.2527/JAS.2017.1440
