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https://hdl.handle.net/2142/20962
Description
Title
Amino acid requirements of growing steers
Author(s)
Titgemeyer, Evan Charles
Issue Date
1989
Doctoral Committee Chair(s)
Merchen, Neal R.
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
Methionine and lysine requirements of growing steers were investigated. In preliminary work, steers were abomasally infused with graded levels (0, 100, 200 and 300 g/d) of casein or mixes of crystalline amino acids simulating the nonsulfur amino acid pattern of casein, both with and without 12 g/d abomasally infused L-methionine (4 replications/treatment). Nitrogen retention increased linearly in response to casein infusion and in response to infusion of the amino acid mixture when methionine was supplemented. Methionine supplementation increased N retention when steers were infused with 200 or 300 g/d of the amino acid mix; postruminal supplementation with nonsulfur amino acids increased response of steers to methionine supplementation. Sulfur amino acid requirements of growing steers were studied in an 8 x 8 Latin Square experiment in which treatments were abomasal infusion of L-methionine (0, 3, 6, 9, 12, 15 or 18 g/d) or DL-methionine (6 g/d). All steers were abomasally infused with 300 g/d of an amino acid mixture simulating the nonsulfur amino acid pattern of casein. Nitrogen retention responses of steers infused with L-methionine and measures of intestinal amino acid flows indicated that steers (294 kg) gaining 1.3 kg/d required 14.7 g/d absorbable sulfur-containing amino acids. Nitrogen retention of steers infused with 6 g/d DL-methionine and those infused with 6 g/d L-methionine were not different, but the efficacy of DL-methionine in supplying sulfur-containing amino acids to steers could not be evaluated because infusion levels were above requirements. Plasma methionine concentrations were higher for steers receiving DL-methionine than for those infused with L-methionine, implying that metabolism of D-methionine by steers is different than that of L-methionine. Lysine requirements of growing steers were studied with a replicated 4 x 4 Latin Square in which treatments were abomasal infusions of L-lysine (0, 8, 16 and 24 g/d). All steers were abomasally infused with 300 g/d of an amino acid mixture simulating casein, except lysine was deleted. Nitrogen retention was not affected by treatment; lysine requirements of 355 kg steers gaining.77 kg/d were less than 40.2 g/d intestinally available lysine.
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