Effects of sequential implanting and ractopamine hydrochloride supplementation on carcass characteristics and longissimus muscle tenderness of calf-fed steers and heifers

A 4 x 2 factorial arrangement of treatments (4 growth-enhancement treatments x 2 sex classes) was used to quantify effects of initial implanting (I-implant, d 0), terminal implanting (T-implant, d 63), and feeding ractopamine hydrochloride [RAC, 200 mg/(animal/d)] for the last 28 d on feed on carcas...

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Bibliographic Details
Published in:	Journal of animal science Vol. 89; no. 1; pp. 201 - 209
Main Authors:	Woerner, D.R, Tatum, J.D, Engle, T.E, Belk, K.E, Couch, D.W
Format:	Journal Article
Language:	English
Published:	Champaign, IL American Society of Animal Science 2011
Subjects:	Adrenergic beta-Agonists - pharmacology Animal Feed animal growth Animal Nutritional Physiological Phenomena Animal productions Animals beef beef cattle beef quality Biological and medical sciences Body Composition - drug effects calves carcass composition carcass quality Cattle cattle feeding Diet - veterinary dietary supplements dosage dose response Drug Combinations Drug Implants Estradiol - administration & dosage Estradiol - pharmacology Female Food industries Fundamental and applied biological sciences. Psychology growth promotion heifers liveweight gain longissimus dorsi Male marbling Meat - standards Meat and meat product industries meat tenderness Muscle, Skeletal - drug effects muscles Phenethylamines - pharmacology ractopamine hydrochloride Sex Characteristics shear strength steaks steers Terrestrial animal productions Time Factors Trenbolone Acetate - administration & dosage Trenbolone Acetate - analogs & derivatives Trenbolone Acetate - pharmacology Vertebrates veterinary drugs Farming animal Ractopamine Bovine Implant Animal feeding Growth Meat product Ox cattle Carcass Vertebrata Meat animals Mammalia Tenderness Livestock Heifer Muscle Artiodactyla Supplementation Ungulata
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Summary:	A 4 x 2 factorial arrangement of treatments (4 growth-enhancement treatments x 2 sex classes) was used to quantify effects of initial implanting (I-implant, d 0), terminal implanting (T-implant, d 63), and feeding ractopamine hydrochloride [RAC, 200 mg/(animal/d)] for the last 28 d on feed on carcass characteristics and LM shear force (WBSF) of calf-fed steers (n = 159) and heifers (n = 132). Growth-enhancement treatments included the following: TRT1, T-implant only; TRT2, I-implant and RAC; TRT3, I-implant and T-implant; TRT4, I-implant, T-implant, and RAC. Growth responses (BW and ADG) were measured in 3 segments of the finishing period: 1) d 0 to 63, 2) d 63 to 28 d before slaughter, and 3) final 28 d. Cattle were slaughtered after 152, 166, or 180 d of finishing; carcass data were collected after a 48-h chill; and LM WBSF was measured at 3, 7, 14, 21, and 28 d postmortem. A priori contrasts were constructed to test effects associated with use vs. exclusion of growth enhancement in each segment of the finishing period. The interaction between sex class and treatment was not significant (P > 0.05) for any trait tested, indicating that the 4 treatments elicited similar effects in both sexes. Initial implanting improved (P < 0.001) ADG from d 0 to 63 by 11.5%, terminal implanting improved (P < 0.001) ADG from d 63 to 28 d before slaughter by 15%, and supplementing twice-implanted cattle with RAC enhanced ADG during the final 28 d of finishing by 12%. Effects of I-implant, T-implant, and RAC resulted in LM area increases of 3 cm² (P = 0.015), 6 cm² (P < 0.001), and 3 cm² (P = 0.011), respectively, and HCW responses of 11 kg (P = 0.011), 16 kg (P = 0.001), and 6 kg (P = 0.195), respectively. Initial implanting resulted in a 20-point reduction (P = 0.097) in marbling, and T-implant reduced marbling by 25 points (P = 0.04), whereas marbling score was unaffected (P = 0.236) by RAC supplementation. Cattle that received only 1 implant (TRT1 and TRT2) produced carcasses with greater (P = 0.026) mean marbling scores and greater (P = 0.01) rates of conformity to beef carcass marketing specifications for HCW, quality grade, yield grade, and LM area than did cattle that were implanted twice (TRT3 and TRT4). Values for LM WBSF were not affected (P > 0.05) by initial or terminal implanting; however, RAC supplementation increased (P = 0.007) mean LM WBSF by 0.23 kg, which translated into a reduction (P = 0.007) in predicted consumer acceptance of LM steaks.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-News-1 ObjectType-Feature-3 content type line 23
ISSN:	0021-8812 1525-3163
DOI:	10.2527/jas.2010-2857