Abstract #690

# 690
Comparison of four beef production systems on carcass characteristics.
Jefferson McCutcheon*1, Steven Moeller1, Henry Zerby1, Francis Fluharty1, 1The Ohio State University, Columbus, OH.

The objective for the study was to compare novel beef production systems to determine the effects of 3 grass finishing regimens on carcass characteristics. This experiment was conducted at 3 research stations in Ohio over 5 yrs. The systems were: STOCK = calves born in March, weaned at 7 mo. of age, grazed in the fall, fed hay in the winter, and then grazed to 16 mo of age and slaughtered; DELAY = calves born in March, not weaned and slaughtered at 10 mo of age; FALL = calves born in September, fed hay when grazing was not possible and not weaned until slaughter in July; and FEED (control) = spring-born counterpart calves from each of the 3 research station locations weaned in October, transported to a feedlot, fed a 90% grain-10% forage diet until reaching 1.0 cm of backfat. All grass systems were conducted in all 3 locations in a randomized block experimental design (blocked by location). Each location had 12 calves and respective cows for each system. Statistics were run using SAS Proc Mixed with PDIFF for mean separation. Slaughter weight was greatest for FEED (505.0 kg, SEM 6.6 kg), followed by STOCK (421.2 kg), FALL (334.2 kg) and DELAY (312.8 kg; P < 0.05). Hot carcass weight was greatest for FEED (299.9 kg, SEM 4.8 kg), followed by STOCK (218.4 kg), FALL (183.3 kg) and DELAY (163.7 kg; P < 0.05). Ribeye area was greatest for FEED (71, SEM 1.7 cm2), followed by STOCK (57.5 cm2), and FALL (52.3 cm2; P < 0.05) with no difference between DELAY (51.5 cm2) and FALL ribeye area (P > 0.05). Backfat was greatest for FEED (1.52 cm, SEM 0.05 cm; P < 0.05) while STOCK (0.58 cm) was not different from FALL (0.51 cm; P > 0.05) and greater than DELAY (0.40 cm; P < 0.05). Marbling scores were greatest for FEED (604 Modest, SEM 18; P < 0.05) with DELAY (495 Slight) being greater than STOCKER (427 Slight) and FALL (419 Slight; P < 0.05). Spring born calves weaned in the fall and placed on feed resulted in heavier carcasses, with greater muscling and back fat than grazing systems. Spring born calves, not weaned and slaughtered at 10 mo. produced a higher quality grade carcass than the other grazing programs. Leaner carcasses were produced from the grazing programs.

Key Words: beef, system, carcass