Beef Quality vs. Quantity in Today's Market
Exogenous growth-enhancing compounds, such as steroidal implants and β-adrenergic agonists (βAA), have been used to improve growth rate and efficiency in meat animals for over a half century. In cattle, these compounds enhance efficiency of growth by preferentially stimulating skeletal muscle growth at the expense of adipose tissue accretion. These compounds have additive effects on carcass gain. Combined use of both these technologies have been shown to increase carcass gain over 35 kg during a typical feeding period. Consequently, these growth-enhancing compounds have been shown to reduce intramuscular fat (marbling) in beef cattle compared to non-treated cattle. This reduction in marbling score has been associated with lower beef quality. These cellular events may in part be responsible for the negative effects observed with the use of these compounds in terms of marbling development in beef cattle. Markers of adipogenic differentiation were also affected by TBA/E2. In adipose tissue, an enzyme important for energy balance, AMPKα, may also be affected by anabolic steroids and βAA. These data indicate that in adipose tissue compared to skeletal muscle, anabolic steroids and βAA may have opposite effects on cellular growth and differentiation. This inverse relationship may contribute to changes in beef quality. Balance is needed to maintain beef quality in light of demands to increase beef production, globally.
Keywords: adipose tissue, beef quality, skeletal muscle