Abstract
As the population increases, it is necessary to improve the sustainability of beef production. Bos indicus (BI) cattle are better adapted to nutritional stress, consume less water, and are better able to withstand thermal stress when compared to Bos taurus (BT) cattle. Additionally, anabolic implants, which typically contain the steroid hormones trenbolone acetate (TBA) and/or estradiol (E2), are commonly administered to beef cattle in the U.S. to improve production. The objective of this study was to determine the effects of cattle breed type and steroid hormones on proliferation of primary bovine satellite cells (BSC). Primary BSC were isolated from the Semimembranosus muscle of Angus (AN; n=2; 100% BT) and Santa Gertrudis (SG; n=2; 19% BI, 81% BT) yearling backgrounded steers and cultured. After the cells reached 70% confluency, cultures were treated with 1% fetal bovine serum (control), 10 nM TBA, 10 nM E2, or 10 nM TBA and E2 and proliferation rates were compared to control cultures. No treatment x breed interaction (P=0.17) was observed. Cultures from AN steers had increased (P=0.007) proliferation rates compared to cultures from SG steers. Steroid hormones increased (P=0.08) proliferation rates, regardless of breed. However, based on this preliminary data, trends are indicating that a breed*treatment interaction is present such that BSC isolated from AN steers are more responsive to treatment than BSC isolated from SG steers. Additional research needs to be completed to determine whether this interaction is still present once more replicates are completed, whether different hormone concentrations affect BSC from cattle of different breed types, and/or the effects of hormone treatment and breed type on BSC relative to differentiation and protein synthesis rate.