Lee

Effect of different dietary protein levels on nitrogen retention in weanling, growing, and finishing pigs

Soybean meal (SBM) is the primary plant-protein source in diets for pigs and provides both amino acids (AA) and energy to the diets. Current estimates for net energy in SBM are less than for cereal grains, based on the assumption that there is more nitrogen to be deaminated if ingredients are high in protein because deamination and excretion of nitrogen via the urea cycle are energy-requiring processes, and therefore, reduce energy efficiency. It has been suggested that pigs retain only 45 to 50% of absorbed nitrogen, which corresponds to 40 to 45% of ingested nitrogen. Modern genotypes of pigs, however, have improved the capacity for protein synthesis and may retain more nitrogen than older genotypes, which would result in less AA deamination and, therefore, less energy loss to deaminate AA and excrete nitrogen. Indeed, results of recent research indicate that pigs fed corn-SBM based diets retain more than 60% of ingested nitrogen, indicating that protein retention by modern genotypes of pigs is more efficient than by older genotypes. It is likely that as breeding companies have selected for leaner pigs, they have also selected genotypes that are more efficient in converting dietary protein into body protein. It is, however, not known if the greater nitrogen retention that has been recently reported is experienced by all pigs regardless of body weight (BW) and if it is true for all types of diets regardless of the dietary level of protein. Therefore, the objective of this experiment was to test the hypothesis that nitrogen retention, measured as a percent of nitrogen consumed, is greater than 50% regardless of the dietary protein level and the BW of pigs.

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Impact of soybean hulls on net energy and nitrogen balance in group-housed pigs allowed ad libitum access to feed

Diets for pigs may vary in composition and in their concentration of the energy containing nutrients (i.e., protein, fat, starch and sugars, and dietary fiber). To our knowledge, however, there is no information on how concentration of net energy (NE) is affected by dietary fiber concentrations in diets fed to group-housed pigs. Therefore, the objective of this experiment was to test the hypothesis that increasing soybean hulls in diets for group-housed growing pigs decreases NE and nitrogen balance.

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Choice white grease equivalence of fat emulsifier in diets fed to growing pigs

Lee, S. A., V. Perez, H. Stein. 2025. Choice white grease equivalence of fat emulsifier in diets fed to growing pigs. Animal - Science proceedings, Volume 16, Issue 2, P. 384. Link to abstract.

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Effect of pistachio shell powder on growth performance of weanling pigs

Kim, Yeonwoo, S. A. Lee, H., Stein. 2025. Effect of pistachio shell powder on growth performance of weanling pigs. Animal - Science proceedings, Volume 16, Issue 2, P. 380. Link to abstract.

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Effects of supplemental phytase on growth performance, blood inositol levels, and immune characteristics of weanling pigs

Mallea, A., S. A. Lee, H. Stein. 2025. Effects of supplemental phytase on growth performance, blood inositol levels, and immune characteristics of weanling pigs. Animal - Science proceedings, Volume 16, Issue 2, P. 374-375. Link to abstract.

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Calcium and phosphorus needs of sows

Stein, H. H., and S. A Lee. 2025. Calcium and phosphorus needs of sows. Pig Progress. Online edition. Aug. 27, 2025. Link to full text.

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Effect of Pistachio Blanks on Growth Performance of Weanling Pigs

Pistachio blanks are co-products from pistachio production and consist of unmarketable pistachio components including the hard outer shells, undersized or unripe kernels, hull fragments, and occasionally woody debris from pruning or sorting operations. As global pistachio production of pistachios increases increased quantities of pistachio byproducts are generated and interest in utilizing some of the co-products in livestock feeding has increased. Data from previous research indicated that pistachio shell powder can be utilized in diets for sows, but because pistachio shell powder and pistachio blanks are very high in fiber, the metabolizable energy in these ingredients fed to weanling pigs is expected to be less than in sows. However, weanling pigs may benefit from the insoluble dietary fiber in pistachio co-products to improve intestinal health, but there are no data to demonstrate effects of including pistachio blanks in diets for weanling pigs. Therefore, an experiment was conducted to test the null-hypothesis that pistachio blanks may be included in diets for weanling pigs without compromising pig growth performance. 

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No increase in green house gas emmission from hybrid rye

Acosta, J. P, S. A. Lee, and H. H. Stein. 2025. No increase in green house gas emmission from hybrid rye. National Hog Farmer. On-line edition. July 31, 2025. Link to full text.

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Impact of soybean meal on nitrogen retention and concentrations of energy in diets fed to growing pigs

Soybean meal (SBM) is often included in cereal-based diets for growing pigs because it provides a well-balanced profile of digestible amino acids (AA), which maximizes growth performance and protein synthesis. However, in recent years, SBM has often been partially replaced by crystalline AA or alternative protein sources such as corn distillers dried grains with solubles (DDGS) or corn protein. These co-products are by-products of the ethanol and vegetable oil industries and are commonly used in swine diets due to their availability and lower cost. Although they provide some indispensable AA, they have a less balanced AA profile and greater fiber concentrations than SBM, which may result in reduced AA digestibility, nitrogen retention, and energy utilization in pigs. However, pigs have become leaner and have greater requirements for dietary AA to support protein synthesis. In addition, it is often assumed that replacing SBM with corn and crystalline AA increases the energy of the diet, but recent data indicate that SBM may provide as much or more digestible energy (DE) and metabolizable energy (ME) than previously estimated. Therefore, it is possible that replacing SBM with corn co-products and crystalline AA may result in a reduction of nitrogen and energy utilization and increase nitrogen excretion in manure. Therefore, the objective of this work was to test the hypothesis that feeding intact protein from SBM to growing pigs, instead of combinations of SBM with crystalline AA or co-products such as DDGS or corn protein, results in greater nitrogen retention and greater DE in the diet without affecting ME.

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Replacement of soybean meal in diets for growing pigs with corn and synthetic amino acids results in reduced energy and nitrogen digestibility and reduced daily nitrogen retention, but metabolizable energy is not changed

Cristobal, Minoy, Su A Lee, Carl M. Parsons, and Hans H. Stein. 2025. Replacement of soybean meal in diets for growing pigs with corn and synthetic amino acids results in reduced energy and nitrogen digestibility and reduced daily nitrogen retention, but metabolizable energy is not changed. Journal of Animal Science, 2025, 103, skaf197.

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Tolerance of weanling pigs and effects on growth performance of supplementing corn-soybean mealbased diets with graded levels of a novel exogenous β-mannanase

Acosta, Jessica P., Su A Lee, Anna Fickler, and Hans H. Stein. 2025. Tolerance of weanling pigs and effects on growth performance of supplementing corn-soybean mealbased diets with graded levels of a novel exogenous β-mannanase. Translational Animal Science, 9, txaf061. doi.org/10.1093/tas/txaf061 Link to full text.

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Release of phosphorus and inositol from soybean meal by growing pigs fed diets with graded levels of microbial phytase

Soybean meal (SBM) is a source of P in diets for swine. However, the P in SBM is stored as part of phytate, and pigs have very limited production of endogenous phytase. Therefore, to improve P availability, commercial pig diets often include supplemental phytase. This practice increases P digestibility, decreases the need for added phosphate, reduces feed costs, and decreases phosphorus excretion in manure. The release of P from phytate in SBM is believed to be in a dose-response manor. In addition, the destruction of phytate that is caused by phytase will also result in release of inositol, which is a sugar that may improve growth performance of pigs. However, there is very limited knowledge about how different levels of phytase influence plasma concentrations of inositol in growing pigs. Therefore, the objective of this work was to test the hypothesis that inclusion of microbial phytase in diets for growing pigs containing SBM will improve the digestibility of P in a dose-response manner and that inclusion of microbial phytase in diets for growing pigs also will increase plasma inositol levels of pigs.

 

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Comparative digestibility of energy and concentrations of energy in corn, soybean meal, and soybean hulls fed to growing pigs and gestating and lactating sows

Kim, Yeonwoo, Su A Lee, Hans H. Stein. 2025. Comparative digestibility of energy and concentrations of energy in corn, soybean meal, and soybean hulls fed to growing pigs and gestating and lactating sows. Journal of Animal Science, Volume 103, Issue Supplement_1, May 2025, Pages 282–283, doi.org/10.1093/jas/skaf102.314 Link to abstract.

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Effects of duration time of heat treatment on amino acid digestibility in enzyme-treated soybean meal fed to weanling pigs

Torres-Mendoza, Leidy J., Su A Lee, Hans H. Stein. 2025. Effects of duration time of heat treatment on amino acid digestibility in enzyme-treated soybean meal fed to weanling pigs. Journal of Animal Science, Volume 103, Issue Supplement_1, May 2025, Pages 168–169, doi.org/10.1093/jas/skaf102.180 Link to abstract.

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Additive effects of 25-hydroxy-vitamin D3 and microbial phytase on digestibility of calcium and phosphorus, blood vitamin D>3 metabolites, and bone biomarkers in growing pigs

Jaramillo, Bibiana M., Su A Lee, Jessica P. Acosta, Hans H. Stein. 2025. Additive effects of 25-hydroxy-vitamin D3 and microbial phytase on digestibility of calcium and phosphorus, blood vitamin D>3 metabolites, and bone biomarkers in growing pigs. Journal of Animal Science, Volume 103, Issue Supplement_1, May 2025, Pages 151–152, doi.org/10.1093/jas/skaf102.162 Link to abstract.

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Digestibility of energy and concentrations of digestible and metabolizable energy in diets containing pistachio blanks fed to growing pigs

Kim, Yeonwoo , Su A Lee, Hans H. Stein. 2025. Digestibility of energy and concentrations of digestible and metabolizable energy in diets containing pistachio blanks fed to growing pigs. Journal of Animal Science, Volume 103, Issue Supplement_1, May 2025, Pages 93–94, doi.org/10.1093/jas/skaf102.100 Link to abstract.

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Effects of using soybean meal, canola meal, and corn distillers dried grains with solubles on net energy, greenhouse gas emission, and nitrogen balance in group-housed pigs

Ibagon, Jimena A., Su A Lee, Hans H. Stein. 2025. Effects of using soybean meal, canola meal, and corn distillers dried grains with solubles on net energy, greenhouse gas emission, and nitrogen balance in group-housed pigs. Journal of Animal Science, Volume 103, Issue Supplement_1, May 2025, Pages 49–50, doi.org/10.1093/jas/skaf102.054 Link to abstract.

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Could soybean meal and high levels of phytase aid pigs in the post-weaning period?

Mallea, A. P., S. A Lee, and H. H. Stein. 2025. Could soybean meal and high levels of phytase aid pigs in the post-weaning period?. National Hog Farmer. On-line edition. May 29, 2025. Link to full text.

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Standardized ileal digestibility of amino acids in pistachio blanks and soybean meal fed to growing pigs

Pistachio blanks are coproducts of pistachio processing and are discarded due to their hollow shells or immature nuts, which make them unusable as human food. Pistachio blanks float in water and the annual production is estimated to be between 50,000 and 70,000 metric tons. A similar coproduct, pistachio shell powder, was recently demonstrated to provide significant amounts of energy in diets for sows. However, there is no information about the digestibility of amino acids (AA) in pistachio blanks when fed to pigs. Although AA concentration in pistachio blanks is low, there is a need for determining standardized ileal digestibility (SID) of AA in pistachio blanks. Therefore, an experiment was conducted to test the hypothesis that the SID of AA in pistachio blanks are comparable to those in soybean meal (SBM) when fed to growing pigs.

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