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- Title
Effects of energy level on methionine utilization by growing steers.
- Authors
Schroeder, G. F.; Titgemeyer, E. C.; Awawdeh, M. S.; Smith, J. S.; Gnadt, D. P.
- Abstract
We evaluated the effect of energy supplementation on Met use in growing steers. Six ruminally cannulated Holstein steers (228 ± 8 kg of BW) were used in a 6 × 6 Latin square and fed 2.8 kg of DM/d of a diet based on soybean hulls. Treatments were abomasal infusion of 2 amounts of Met (0 or 3 g/d) and supplementation with 3 amounts of energy (0, 1.3, or 2.6 Mcal of GE/d) in a 2 × 3 factorial arrangement. The 1.3 Mcal/d treatment was supplied through ruminal infusion of 90 g/d of acetate, 90 g/d of propionate, and 30 g/d of butyrate, and abomasal infusion of 30 g/d of glucose and 30 g/d of fat. The 2.6 Mcal/d treatment supplied twice these amounts. All steers received basal infusions of 400 g/d of acetate into the rumen and a mixture (125 g/d) containing all essential AA except Met into the abomasum. No interactions between Met and energy levels were observed. Nitrogen balance was increased (P < 0.05) by Met supplementation from 23.6 to 27.8 g/d, indicating that protein deposition was limited by Met. Nitrogen retention increased linearly (P < 0.05) from 23.6 to 27.7 g/d with increased energy supply. Increased energy supply also linearly reduced (P < 0.05) urinary N excretion from 44.6 to 39.7 g/d and reduced plasma urea concentrations from 2.8 to 2.1 mM. Total tract apparent OM and NDF digestibilities were reduced linearly (P < 0.05) by energy supplementation, from 78.2 and 78.7% to 74.3 and 74.5%, respectively. Whole-body protein synthesis and degradation were not affected significantly by energy supplementation. Energy supplementation linearly increased (P < 0.05) serum IGF-I from 694 to 818 ng/mL and quadratically increased (P < 0.05) serum insulin (0.38, 0.47, and 0.42 ng/mL for 0, 1.3, and 2.6 Mcal/d, respectively). In growing steers, N retention was improved by energy supple- mentation, even when Met limited protein deposition, suggesting that energy supplementation affects the efficiency of AA use.
- Subjects
ANIMAL nutrition; FEED additives; HOLSTEIN-Friesian cattle; SOY bran; BEEF cattle; URINALYSIS; METHIONINE; NITROGEN excretion; ANIMAL feeding; ANIMAL industry
- Publication
Journal of Animal Science, 2006, Vol 84, Issue 6, p1497
- ISSN
0021-8812
- Publication type
Article
- DOI
10.2527/2006.8461497x