摘要：This experiment investigated the benefits of feeding steers bred from parents known to be of high genetic merit for feed efficiency (HE; midparent net feed intake-estimated breeding value (NFI-EBV) ≤-0.3kg/day), medium efficiency (ME: midparent NFI-EBV >-0.3 to 0.14 kg/day), or low efficiency (LE; midparent NFI-EBV ≥0.16kg/day). The steers were evaluated over a 251-day feeding period in a large commercial feedlot. Genetic superiority in NFI had a favourable impact on the commercial performance of Angus steers by reducing feed consumed with no adverse effect on final turnoff weight. Each HE steer consumed on average 2.60t of feed compared to 2.87t by the ME and LE steers, with no compromise in weight gain. The HE steers gained less subcutaneous ribfat during the feedlot period but marbling scores were not influenced by NFI, and dressing percentage was higher in the HE steers. The feed efficiency benefit was sustained for 251 days and showed that genetic improvement of feed efficiency will reduce feed costs in a large commercial feedlot.
