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Whole-body and tissue protein synthesis in steers losing weight on a low-protein roughage diet: the effect of trenbolone acetate

Published online by Cambridge University Press:  27 March 2009

R. A. Hunter
Affiliation:
CSIRO, Division of Tropical Animal Production, Tropical Cattle Research Centre, North Rockhampton, Queensland 4702, Australia
T. Magner
Affiliation:
CSIRO, Division of Tropical Animal Production, Tropical Cattle Research Centre, North Rockhampton, Queensland 4702, Australia

Summary

Six Brahman (Bos indicus) steers implanted with 300 mg trenbolone acetate and six similar nonimplanted steers were fed a low-quality, low-protein roughage diet at 10 g dry matter/kg live weight. They were housed in individual pens for 27 days in 1987 before being placed in metabolism crates for measurement of digestibility, nitrogen retention, and the rate of protein synthesis in the whole body and fractional rate in three muscles and hide.

The rate of weight loss of steers treated with trenbolone acetate was significantly (P < 0·05) less than that of controls (–0·34 v. –0·56 kg/day). Treated steers excreted significantly (P < 0·05) less 3-methylhistidine (128 v. 202 μmol) and urea N (0·5 v. 1·6 g/day) in urine. There was a more favourable nitrogen retention in animals implanted with trenbolone acetate (–10 v. –12g/day) but this difference was not significant.

Whole-body protein synthesis, calculated from plasma leucine flux, was 511 and 508 g/day in treated and control steers, respectively. Treatment also had no significant effect on the fractional rate of protein synthesis, in skeletal muscle or in hide. The fractional rate of synthesis in muscle was < 1%/day and in hide < 2%/day. These results are discussed in relation to the protein and energy metabolism of undernourished cattle.

Type
Animals
Copyright
Copyright © Cambridge University Press 1990

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