Effects of ractopamine hydrochloride and zilpaterol hydrochloride supplementation on carcass cutability of calf-fed Holstein steers.
Effects of ractopamine hydrochloride (RH) and zilpaterol hydrochloride (ZH) on saleable yield of carcass sides from calf-fed Holstein steers were evaluated using steers implanted with a progesterone (100 mg) plus estradiol benzoate (10 mg) implant followed by a terminal trenbolone acetate (200 mg) plus estradiol (40 mg) implant. Steers were blocked by weight into pens (n = 32) randomly assigned to one of four treatments: control, RH fed at 300 mg•steer(-1)/d(-1) (RH 300) or RH fed at 400 mg•steer(-1)/d(-1) (RH 400) the final 31 d of finishing, and ZH fed at 60 to 90 mg•steer(-1)/d(-1) (7.56 g/ton on a 100% DM basis) for 21 d with a 5 d withdrawal before harvest. Eight to nine carcass sides were randomly selected from each pen; carcass sides with excessive hide pulls, fat pulls or bruises were avoided. Cutout data were collected within a commercial facility using plant personnel to fabricate sides at a rate of one every 3 to 4 min into items typically merchandised by the facility. All lean, fat and bone were weighed and summed back to total chilled side weight with a sensitivity of ± 2% to be included in the data set. Compared to controls, β-agonists increased saleable yield of whole-muscle cuts by 0.61%, 0.86% and 1.95% for RH 300, RH 400 and ZH, respectively (P < 0.05). Percent fat was less in carcasses from the ZH treatment compared to controls (P < 0.05); however, this difference was not observed between RH treatments and controls (P > 0.05). Percent bone was less in the ZH treatment due to increased muscle (P < 0.05). The percent of chilled side weight comprised of trimmings was unchanged between treatments, but on a 100% lean basis, RH 400 and ZH increased trim yields (P < 0.05). Analysis of saleable yield by primal showed a fundamental shift in growth and development. Beta-agonists caused a shift in proportion of saleable yield within individual primals, with a greater portion produced from the hindquarter relative to the forequarter, specifically in those muscles of the round (P < 0.05). Beta-agonists increased saleable yield, but these effects were not constant between all major primals. The cutout value gained by packers as a result of β-agonist use may be influenced more by reduced fatness and increased absolute weight if musculature is primarily increased in the lower priced cuts of the carcass.
Department of Animal Science, Colorado State University, Fort Collins 80523-1171.
S T
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Howard
D R
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Woerner
D J
DJ
Vote
J A
JA
Scanga
R J
RJ
Acheson
P L
PL
Chapman
T C
TC
Bryant
J D
JD
Tatum
K E
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Belk
D000318:Adrenergic beta-Agonists / Q000008:administration & dosage / Q000378:metabolism*; D000821:Animal Feed / Q000032:analysis; D000818:Animals; D001823:Body Composition / Q000187:drug effects*; D002417:Cattle / Q000502:physiology*; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements / Q000032:analysis; D004343:Drug Implants / Q000008:administration & dosage / Q000494:pharmacology; D004958:Estradiol / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D008460:Meat / Q000032:analysis*; D018482:Muscle, Skeletal / Q000187:drug effects*; D010627:Phenethylamines / Q000008:administration & dosage / Q000378:metabolism*; D011374:Progesterone / Q000008:administration & dosage / Q000494:pharmacology; D014204:Trenbolone Acetate / Q000008:administration & dosage / Q000494:pharmacology; D014297:Trimethylsilyl Compounds / Q000008:administration & dosage / Q000378:metabolism*
D000318:Adrenergic beta-Agonists; D004343:Drug Implants; D010627:Phenethylamines; D014297:Trimethylsilyl Compounds; C475840:Zilpaterol; C074283:estradiol 3-benzoate; D011374:Progesterone; D004958:Estradiol; C060897:ractopamine; D014204:Trenbolone Acetate