Effects of differences in level of post-weaning nutrition and in sire expected progeny differences for ribeye area on retail cuts yield in Hereford steers

Abstract

Context Uninterrupted nutrient uptake and the use of bulls with high genetic merit for carcass traits may increase the likelihood of producing high-quality retail cuts for different markets. Aim The objective of this experiment was to evaluate the combined effects of level of nutrition during the 104-day post-weaning winter period (WADG; low-L: 0.2 vs high-H: 0.6 kg/calf per day) and level of expected progeny differences (EPD) for ribeye area (REA; high-H or average-Av) on carcass traits and retail cuts of Hereford steers. Methods Three crops of calves (n = 317) were selected according to REA (H-REA vs Av-REA), blocked for weaning weight (WW) and randomly allotted to one of the two WADG treatments (L-WADG vs H-WADG) for 104 days. Experimental design was a completely random block and the treatments were the combination of two factors (2 × 2). After winter (L-WADG and H-WADG groups), all calves grazed on improved pastures (herbage allowance: 5% of liveweight (LW) per day). The finishing was done on a feedlot and started when the group average of animals reached a full LW (FLW) of 350 ± 28 kg. Cattle were harvested at a constant final FLW of 525 ± 40 kg. Key results No interaction was observed (P > 0.05) between WADG and REA for carcass traits. Animals with H-WADG presented higher (P < 0.05) hot carcass weight (HCW) and dressing-out (%) than L-WADG. High REA and H-WADG steers showed higher weight (kg) in the rump and loin, striploin, sirloin, and lean component in the pistola cut (P < 0.01). Likewise, H-REA and H-WADG presented a greater proportion of rump and loin (P < 0.01) and lean (%) (P < 0.05) than Av-REA and L-WADG, respectively. Conclusions The combined effects of greater post-weaning winter gains and high REA EPD allow slaughter of younger steer with greater lean proportion and retail cuts. Implications No interaction between the REA and WADG allows producers to plan economic benefits through a higher WADG in the first winter phase as well as using superior bulls for carcass traits to achieve heavier retail cuts.