The influence of growth stage on carcass composition and factors associated with marbling development in beef cattle.

摘要: Subcutaneous fat and marbling both increase in beef cattle during the feeding phase but are antagonistic regard to their contribution carcass value. The objective of this study was determine whether cellular factors associated with development change growth stage throughout period they correlated relative composition. Twenty-four steers known origin cytosine thymine (CT) leptin genotype were allotted 3 harvest groups. Six per group harvested at following predetermined points: 35 d on feed (early period, EF), average live weight 464 kg (middle MF), 1.17-cm 12th-rib subcutaneous thickness (late LF). Longissmus muscle samples collected within 30 min postmortem snap frozen for real-time PCR Western blot analysis lipoprotein lipase, adenosine monophosphate-activated protein kinase α (AMPKα), stearoyl-coenzyme A desaturase (SCD), PPARγ, C/EBP-β, myostatin. Carcass data recorded, LM aged 2, 7, 14, 21 Warner-Bratzler shear force determination. composition estimated by dissection 9-10-11 rib section subsequent proximate soft tissue. Intramuscular content increased linearly giving additional support as an early developing Expression AMPKα found be downregulated, whereas SCD expression upregulated LF first 2 Additionally, PPARγ downregulated EF latter These changes gene resulted a linear only abundance, myostatin tended quadratically. correlation between intramuscular abundance. This gives further evidence importance adipocyte hyperplasia increasing marbling. Targeting may serve mechanism deposition. Last, steaks more tender than MF or steaks, indicating improved tenderness days feed.