57 Effect of diet mixing strategies on growth performance and carcass characteristic in feedlot steer

Abstract Our objective was to determine the effects of a feeding management strategy on growth and carcass quality and characteristics on finishing feedlot beef cattle. Angus-Simmental steers (n = 60), blocked by body weight (BW), were housed in individual pens and randomly assigned to treatments. Treatments were total mixed ration (TMR) or a non-mixed diet (Split). The diet contained 67.5% of dry rolled corn, 18% of distiller grains with soluble, 2.5% soybean meal, 7% hay, and 5% of mineral and vitamin mixed. The diet composition for both treatments was similar, the only difference was the use of a TMR or that the concentrate was fed separately from the hay on the Split treated calves. Feed intake was monitored through slick bunk management in both treatments. For the Split assigned calves, if any hay or concentrate was left in the bunk on two consecutive days, the total feed was decreased by 5%; maintaining always the 93% concentrate and 7% forage ratio. Steers were weighed monthly and feed samples were collected for nutrient composition analysis semimonthly. Monthly weights and intakes were used to calculate average daily gain (ADG) and gain to feed ratio (G:F). Steers were slaughtered per block when the average weight of the block reached 555 kg. Carcasses were evaluated 48 h post slaughter. Carcass yield and quality factors were evaluated at the 12th/13th rib interface. Data were analyzed as randomized complete block design. Considering the fixed effect of the feeding strategy and the random effect of block. We did not observe differences (P > 0.17) in growth performance or carcass characteristics variables due to management strategy (Table 1). The lack of observed differences due to treatment might be because the ratio of concentrate and forage intake was similar for both groups, in addition to the slick bunk management in both treatments, which forced steers to eat all their ration, independent of the treatment, to continue to receive the same amount of feed.