Protein turnover and sensory traits of longissimus muscle from implanted and nonimplanted heifers1

Abstract

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.

Effect of growth-promoting technologies on Longissimus lumborum muscle fiber morphometrics, collagen solubility, and cooked meat tenderness12

“…Platter et al (2003) found that implanted heifers maintained greater WBSF values through 21 d of aging. In agreement, Kerth et al (2003) and Boles et al (2009) also found that implanting heifers did not affect WBSF values at up to 21 d of aging.…”

Influence of Close-Up Starting Programs on Performance of Light-Weight Feedlot Steers Calves during the Early Receiving Period

“…However, in the present study, steers received growth implants, as is the common practice in the industry [8]. Hormonal implants enhance amino acid uptake by muscle cells [15], increasing the number of satellite cells, rate of cell proliferation, and protein synthesis, and decreasing rate of protein degradation [16]. The net effect is a potential for increased N retention, provided cattle receive adequate metabolizable protein [17]- [20].…”

Effects of hormonal growth promotants (HGP) on growth, carcass characteristics, the palatability of different muscles in the beef carcass and their interaction with aging

“…Some studies have reported no effect of testosterone and oestradiol on protein synthesis or degradation rates (Roeder et al 1986;Desler et al 1996), although others have shown an increase in protein synthesis alone (Martinez et al 1984;Hayden et al 1992). Kerth et al (2003) concluded that implantation of cattle with trenbolone acetate impacted both synthesis and degradation, with perhaps the strongest effect on protein synthesis.…”

“…There is mounting evidence that HGPs increase efficiency and growth rates of cattle by modifying protein turnover rates in the body (Kerth et al 2003;Dunshea et al 2005). In reviewing the interaction between protein turnover and eating quality, Koohmaraie et al (2002) proposed that if in part an increase in net protein in the live animal was achieved by a decrease in protein turnover (i.e.…”