SciELO - Scientific Electronic Library Online

 
vol.41 issue1Broiler performance and bone strength minimally affected by either a simulated dusk or night-interruption photoperiodSaccharomyces cerevisiae cell wall products: the effects on gut morphology and performance of broiler chickens author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Services on Demand

Article

Indicators

Related links

  • On index processCited by Google
  • On index processSimilars in Google

Share


South African Journal of Animal Science

On-line version ISSN 2221-4062
Print version ISSN 0375-1589

Abstract

WALKER, D.K. et al. Effects of ractopamine and gender on protein turnover in skeletal muscle of implanted steers and heifers. S. Afr. j. anim. sci. [online]. 2011, vol.41, n.1, pp.16-23. ISSN 2221-4062.

Effects of the β-agonist, ractopamine-HCl (ractopamine), on skeletal muscle protein turnover were evaluated in 16 steers (512 kg) and 16 heifers (473 kg). Treatments were arranged in a 2 × 2 factorial design and included gender (steer vs. heifer) and ractopamine (0 or 200 mg/d). Steers were implanted with 120 mg trenbolone acetate and 24 mg estradiol-17β, heifers with 140 mg trenbolone acetate and 14 mg estradiol-17β. Cattle were fed a diet based on steam-flaked maize. Muscle biopsy samples were collected fromm. longissimus and m. biceps femoris on day 0 (prior to ractopamine feeding) and after 14 and 28 d of ractopamine feeding. In vitro protein synthesis rates in m. longissimus tended to be greater for steers than for heifers, but no effect of gender was observed in m. biceps femoris. Gender did not affect in vitro protein degradation rates for either muscle. Ractopamine significantly decreased rates of in vitro protein degradation in m. longissimus, but rates in m. biceps femoris were not affected by ractopamine. Ractopamine did not affect in vitro protein synthesis rates. In general, there were no striking differences between steers and heifers in response to ractopamine, indicating that its effectiveness should be similar between genders.

Keywords : Cattle; β-agonist; protein turnover; ractopamine.

        · text in English     · English ( pdf )

 

Creative Commons License All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License