nitrogen balance

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 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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Effect of soy isoflavones and nitrogen-source on nitrogen balance in low-protein diets fed to growing pigs

Soybean meal (SBM) is the primary source of amino acids (AA) and energy in diets for swine throughout the world. However, less SBM is often used in diets to decrease nitrogen (N) excretion and environmental pollution. Nonetheless, it is demonstrated that lowering dietary protein does not consistently deliver the same performance of pigs as of pigs fed high protein diets, even though all indispensable AA meet the requirements of pigs. It is possible that soybean-derived bioactive compounds (i.e., soy isoflavones and saponins) in SBM act as immunomodulators, which improve the performance of pigs. It is also possible that low-protein diets contain N below the requirements for pigs to maximize growth. However, no data are available to prove this hypothesis. Therefore, the objective of this experiment was to test the hypothesis that N balance of pigs is not affected by reducing dietary protein if soy isoflavones or N source are supplemented in diets.

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Effects of dietary isoleucine and valine supplementation to excess or low leucine diets on nitrogen balance and metabolism of branched-chained amino acids in growing pigs

Kwon, Woong B., Jose A. Soto, Hans H. Stein. 2020. Effects of dietary isoleucine and valine supplementation to excess or low leucine diets on nitrogen balance and metabolism of branched-chained amino acids in growing pigs. J. Anim. Sci. 98(Suppl. 3): 33. doi.org/10.1093/jas/skaa054.059. (Abstr.). Link to abstract.

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Effects on nitrogen balance and metabolism of branched-chain amino acids by growing pigs of supplementing isoleucine and valine to diets with adequate or excess concentrations of dietary leucine

Kwon, Woong B., Jose A. Soto, and Hans H. Stein. 2020. Effects on nitrogen balance and metabolism of branched-chain amino acids by growing pigs of supplementing isoleucine and valine to diets with adequate or excess concentrations of dietary leucine. Journal of Animal Science, 2020, Vol. 98, No. 11, 1–10. doi:10.1093/jas/skaa346.

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Effects of dietary isoleucine and valine supplementation to excess or low leucine diets on nitrogen balance and metabolism of branched-chain amino acids in growing pigs

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.

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Effects of dietary leucine concentration on branched-chain amino acid metabolism in growing pigs

Kwon Woong B., Kevin J. Touchette, Aude Simongiovanni, Kostas Syriopoulos, Anna Wessels, Hans H. Stein. 2019. Effects of dietary leucine concentration on branched-chain amino acid metabolism in growing pigs. Journal of Animal Science, Volume 97, Issue Supplement_2, July 2019, Pages 65–66. (Abstr.). Link to abstract.

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