Protein turnover and sensory traits of longissimus muscle from implanted and nonimplanted heifers

• Published in: Journal of animal science Vol. 81; no. 7; pp. 1728 - 1735
• Main Authors: Kerth, C.R, Montgomery, J.L, Morrow, K.J, Galyean, M.L, Miller, M.F
• Format: Journal Article
• Language: English
• Published: Savoy, IL Am Soc Animal Sci 01-07-2003; American Society of Animal Science
• Subjects: Amino Acids - metabolism; Animal productions; Animals; Biological and medical sciences; blood; blood proteins; Cattle - metabolism; cell culture; Cells, Cultured; Consumer Behavior; Drug Combinations; Drug Implants; Estradiol - administration & dosage; Estradiol - pharmacology; Female; Fundamental and applied biological sciences. Psychology; heifers; Humans; longissimus muscle; Meat - standards; muscle protein; Muscle Proteins - metabolism; Muscle, Skeletal - cytology; Muscle, Skeletal - drug effects; Muscle, Skeletal - physiology; myocytes; palatability; protein degradation; protein synthesis; sensory properties; steaks; Taste; Terrestrial animal productions; Testosterone; Trenbolone Acetate - analogs & derivatives; Vertebrates; Production quality; Ruminant animal; Organoleptic properties; Meat product; Anabolic Agents; Ox; Turnover; Beef cattle; Muscle Cells; Beef; Ungulata; Farming animal; Bovine; Muscular fiber; Experimental study; Vertebrata; Mammalia; Palatability; Treatment; Protein Turnover; Protein synthesis; Animal protein; Rearing; Heifer; Artiodactyla; Anabolic agent
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/2003.8171728x

Primary bovine muscle cell culture studies were conducted to determine whether implanting heifers had a direct effect on in vitro protein synthesis and degradation and to determine the effect of implanting heifers on longissimus muscle palatability. Feedlot heifers (n = 96) were administered one of six implant regimens to characterize their effect on in vitro amino acid uptake and protein degradation. Treatments consisted of: 1) a nonimplanted control (NI/NI); 2) no implant on d 1 and Revalor-H administered on d 84 of the experiment (NI/Rev); 3) Revalor-H on d 1, but no implant given at d 84 (Rev/NI); 4) Revalor-H administered on d 1 and d 84 (Rev/Rev); 5) Revalor-IH administered on d 1 and Revalor-H at d 84 (RIH/Rev); and 6) Synovex-H given at d 1 and Revalor-H administered at d 84 (Syn/Rev). Blood and longissimus lumborum muscle were collected 20 min postmortem, and serum and muscle extracts were incubated with primary bovine muscle cells. Implant treatments had minimal effects on shear force and sensory traits; however, steaks from Rev/Rev heifers were 0.31 kg more tender (P < 0.05) than steaks from NI/NI heifers. Serum protein synthesis and degradation were not affected (P > 0.10) by any implant treatment. When primary bovine muscle cells were treated with muscle extract, amino acid uptake was greater for heifers implanted with Rev/Rev than for the average of all other treatments (P < 0.01). The Rev/Rev implant regimen also increased (P < 0.05) amino acid uptake compared with heifers treated with RIH/Rev, Syn/Rev, NI/NI, NI/Rev, or Rev/NI. Cellular protein degradation of the muscle cell culture treated with muscle extract tended (P < 0.10) to be higher in NI/NI-treated cells compared with the average of all implant treatments. In addition, cells treated with muscle extract from heifers implanted with Rev/Rev had lower (P < 0.05) protein degradation than the NI/NI control heifers. These results indicate that anabolic implant strategies can directly affect both muscle protein synthesis and degradation via effects that seem to be more autocrine than paracrine in nature.