Leucine is a key regulator that stimulates catabolism of branched-chain AA (BCAA; i.e., Leu, Ile, and Val) in skeletal muscle and liver. If diets fed to pigs contain excess Leu, catabolism of all 3 BCAA may increase because of the stimulating effect of the Leu metabolite, α-keto isocaproate, on the branched-chain α-keto acid dehydrogenase enzyme complex, which is responsible for degradation of the 3 branched-chain α-keto acids that originate from metabolism of the 3 BCAA. Serum Ile and Val concentrations were reduced by excess dietary Leu in growing pigs, and high dietary Leu reduces feed intake and growth performance in pigs, which may be a result of the imbalanced supply of BCAA that result from increased metabolism of Val and Ile. Recent data confirmed that excess dietary Leu reduced growth performance and tended to reduce protein synthesis, which is likely a result of reduced availability of Val and Ile.

NexPro is a high protein feed ingredient that is generated via downstream processing of co-products from the dry-grind ethanol industry. Results from digestibility experiments indicate that NexPro contribute considerable quantities of amino acids and energy to diets fed to pigs, but there are no data demonstrating effects on growth performance of including NexPro in diets for weanling pigs. Therefore, an experiment was conducted to test the hypothesis that NexPro may replace other high-value protein sources in diets for weanling pigs without impacting pig growth performance.

Espinosa, C. D., R. S. Fry, M. E. Kocher, H. H. Stein. 2020. Effects of copper hydroxychloride and dietary fiber on intestinal permeability, growth performance, and blood characteristics of nursery pigs. Animal Feed Science and Technology 263 (2020) 114447. Link to full text.

Kwon, W. B., and H. H. Stein. 2020. Tryptophan can partially overcome negative effects of leucine in pig diets. National Hog Farmer, Online edition. Jan.

Exogenous carbohydrases can be used in diets for pigs to increase digestibility of dietary fiber and energy in cereal grains and cereal co-products. The three main fibers in cereal grains and cereal co-products are arabinoxylans, cellulose, and mixed-linked beta glucans. The fermentability is different among these three types of fiber. Energy digestibility is often improved if xylanase is added to wheat-based diets, whereas positive responses to xylanase in corn-based diets have been difficult to demonstrate, indicating that fermentation of dietary fiber differs among ingredients. However, there is less information about effects of carbohydrases on digestibility of fiber and energy in sorghum-based diets. Therefore, an experiment was conducted to test the hypothesis that xylanase and cellulase improve the digestibility of energy and total dietary fiber in diets based on corn or sorghum with addition of high fiber co-products.

Casas, Gloria A., Laia Blavi, Tzu-Wen L. Cross, Anne H. Lee, Kelly S. Swanson, and Hans H. Stein. 2020. Inclusion of the direct-fed microbial Clostridium butyricum in diets for weanling pigs increases growth performance and tends to increase villus height and crypt depth, but does not change intestinal microbial abundance. Journal of Animal Science, 2020, 1–12. doi:10.1093/jas/skz372.

Recent research conducted at the University of Illinois Swine Research Center demonstrated positive effects of feeding copper hydroxychloride to weanling pigs, including improved growth performance and positive changes in intestinal health. It is, however, not known if copper hydroxychloride would also elicit positive effects in growing-finishing pigs. Additionally, it is also not known if the positive effects of copper hydroxychloride are obtained regardless of the origin of the mineral, or if the response is specific to the product produced by a specific supplier. Therefore, an experiment was conducted to test the hypothesis that inclusion of copper hydroxychloride in diets for growing-finishing pigs would improve growth performance, and secondly that the origin of the copper hydroxychloride is not important for the outcome.

Rye contains considerable quantities of intrinsic phytase and the presence of phytase in rye may result in an increased P digestibility in pigs without using exogenous phytase. It is possible that the endogenous phytase in rye also increases P digestibility in other plant feed ingredients by releasing P from the phytate. However, to our knowledge, no data demonstrating this effect have been published. Therefore, the objective of this experiment was to test the hypothesis that inclusion of rye in diets containing corn and soybean meal (SBM) without or with microbial phytase improves the apparent total tract digestibility (ATTD) of P and Ca and thus the ATTD of P is not additive in the mixed diet.

Galkanda‐Arachchige, Harsha S. C., Jingping Guo, Hans H. Stein. Donald Allen Davis. 2020. Apparent energy, dry matter and amino acid digestibility of differently sourced soybean meal fed to Pacific white shrimp Litopenaeus vannamei. Aquaculture Research. 2020;51:326–340, DOI: 10.1111/are.14378. Link to full text.