nitrogen retention

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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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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Impact of soybean oil 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 fat concentrations in diets fed to group-housed pigs. Therefore, the objective of this experiment is to test the hypothesis that increased soybean oil in diets for group-housed growing pigs will increase NE and nitrogen balance.

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Determination of net energy and nitrogen balance in group-housed pigs fed diets containing varying levels of starch and fiber

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 starch and fiber concentrations in diets fed to group-housed pigs. Therefore, the objective of this experiment is to determine NE and nitrogen balance in diets containing various levels of starch and fiber fed to group-housed pigs.

 

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Soybean meal or crystalline amino acids in diets for growing pigs: Impact on diet net energy, pig growth performance, and nitrogen retention

Stein, Hans H. Jimena A. Ibagon, Minoy Cristobal. 2024. Soybean meal or crystalline amino acids in diets for growing pigs: Impact on diet net energy, pig growth performance, and nitrogen retention. Proc. 23nd Annual Midwest Swine Nutrition Conf. Danville, IN, Sep. 5, 2024. Pages 45-51.

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Effects of supplemental d-methionine in comparison to l-methionine on nitrogen retention, gut morphology, antioxidant status, and mRNA abundance of amino acid transporters in weanling pigs

Espinosa, Charmaine D., John K. Mathai, Laia Blavi, Yanhong Liu, John K. Htoo, J. Caroline Gonzalez-Vega, and Hans H. Stein. 2021. Effects of supplemental d-methionine in comparison to l-methionine on nitrogen retention, gut morphology, antioxidant status, and mRNA abundance of amino acid transporters in weanling pigs. Journal of Animal Science, 2021, Vol. 99, No. 9, 1–10. doi.org/10.1093/jas/skab248.