Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: May 31, 1996
Publication Date: N/A
Steers from Red Pol or Simmental sires and crossbred dams (236 kg body weight; n=30 per year) were stratified by weight and randomly assigned within weight groups to two pasture treatments and three slaughter dates over two years. The pasture treatments were wheat pasture until May 1 (WHT) and Agrotricum, a wheat-wheatgrass cross with extended grazing, until lJune 1 (AGR). Five steers from each treatment were slaughtered about June 1, five about 45 days later and five 90 days later. This provided a range of 168 to 228 days on wheat pasture and of 0 to 120 days on feed. Gains on pasture were 1.12 kg/d for WHT and .96 kg/d for AGR in 1993-94 and 1.05 for both treatments in 1994-95 (interaction P<.01). The steers averaged 436 kg for WHT and 452 kg for AGR (P<.01) at the end of the pasture phase (year X treatment, P<.01). Feedlot gains were 1.03 kg/d and did not differ among treatments or years (P>.05). USDA carcass quality grade was 348 for WHT and 381 for AGR (P<.10; 400=low choice) and increased quadratically with days on feed (P<.10) with different slopes for each pasture treatment (P<.10). The number of carcasses grading select or choice was not different (P>.05) for treatments and averaged 85%. The number grading choice averaged only 31%, and increased quadratically (P<.05) with days on feed. In 1993-94, 56% of the carcasses were yield grade 3.0 or less and none exceeded 3.5. In 1994-95 only one of the thirty exceeded 3.0. These data indicate that quality lean beef can be produced when 90 percent of the slaughter weight is produced on high quality forage.