EFFECTS OF PLACING CATTLE ON FEED AT 2-MONTH INTERVALS AND HOUSING ON FEEDLOT PERFORMANCE AND CARCASS GRADES

A 5-yr study was conducted involving the placement of yearling steers on feed at 2-mo intervals under three different housing systems. A total of 3,571 steers (180 pens) initially averaging 318 kg was used. Evaluations were made for DM intake, ADG, feed efficiency (FE), carcass quality (QG), and yield grades (YG). Cattle were assigned to either an open lot with overhead shelter (S), an open lot without overhead shelter (NS), or an open-front confinement building (C). Each treatment consisted of two lots of 20 steers each per interval per trial. Corn grain provided 85% of the energy; the remainder was supplied by corn silage and protein supplement. Cattle were fed 140 to 180 d to achieve an average slaughter weight of 500 kg. The main effects of year (Y), month (M), and housing (H) affected DM intake, ADG, FE, and final live weight (P < .01). The interactions for Y x M, M x H and Y x M x H affected ADG (P < .05). Month and H affected hot carcass weight (P < .01). Year affected YG, and year and month affected QG (P < .01). Month effects on DM intake and ADG indicated that cattle started in May had the highest intake and ADG (P < .05) and that cattle started in November had the lowest (P < .05) DMI and ADG. Month effects on FE indicated that cattle were most efficient when placed on feed during March, May, and July (5.82, 5.72, and 5.66 kg DM/kg gain; P < .05). Housing effects indicated that S cattle had the highest DM intake, ADG, and FE (7.79, 1.29, and 6.15 kg; P < .05) and that C had the lowest DM intake and ADG (6.97 and 1.09 kg; P < .05). Body composition, as determined by YG and QG, was relatively unaffected by the season or housing. These results indicate that starting time on feed and housing system significantly influenced cattle feedlot performance without influencing body composition.