A Re-Evaluation of Amino Acid Requirements of Lactating Sows
Soltwedel, Kevin T.
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https://hdl.handle.net/2142/83583
Description
Title
A Re-Evaluation of Amino Acid Requirements of Lactating Sows
Author(s)
Soltwedel, Kevin T.
Issue Date
2005
Doctoral Committee Chair(s)
James Pettigrew
Department of Study
Animal Sciences
Discipline
Animal Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Animal Culture and Nutrition
Language
eng
Abstract
The literature contains widely differing amino acid requirement estimates for milk production and the mobilization of amino acids from sow body tissues, and both impact estimates of dietary amino acid requirements. Five experiments were conducted to evaluate amino acid requirements calculated from these different inputs. Inputs evaluated included four sets of amino acid requirement ratios for milk synthesis, and three sets of amino acid ratios assumed to be mobilized from sow body tissue. Experiment (Exp) 1 confirmed that plasma urea nitrogen concentration (PUN) could be used as an indicator of limiting amino acids in diets of lactating sows. Subsequently, Exp 2 and 3 were conducted to determine the order of limitation for lysine (Lys), threonine (Thr), and valine (Val) in diets of lactating sows experiencing high body weight (BWT) loss in lactation, using PUN as an indicator. The results suggested that Lys is first-limiting and Thr second-limiting. However, diets used in Exp 2 and 3 were fed over short 4-d periods. Therefore, Exp 4 was conducted to evaluate the dietary Thr:Val requirement of lactating sows over a full lactation period. Results of Exp 4 demonstrated that Thr was more limiting than Val in a diet formulated to a Thr:Val ratio near that of a corn-soybean meal lactation diet. Results of Exp 2, 3, and 4 indicated that NRC (1998) inputs either underestimate the Thr requirement or overestimate the Val requirement. Therefore, Exp 5 was conducted to further evaluate Thr and Val requirements of lactating sows. The specific objective of Exp 5 was to determine the level of L-lys•HCl supplementation (0.0, 0.1, and 0.3%) of a Lys-deficient corn-soybean meal diet (0.65% digestible Lys) at which the Thr:Lys and/or Val:Lys ratios limit sow and litter performance. Results of Exp 5 indicated that inputs from measures of mammary amino acid uptake overestimated Thr and Val requirements. In conclusion, the results of these five experiments give useful information as to which amino acid requirement ratios are most appropriate for lactating sows. These include the requirement ratios from NRC (1998) with the exception of Val, whose requirement may have been overestimated by NRC (1998).
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