Finishing steers on winter annual ryegrass (Lolium multiflorum Lam.) with varied levels of corn supplementation I: effects on animal performance, carcass traits, and forage quality

Crossbred steers (n = 72) were selected to study forage-based finishing systems using winter annual ryegrass (Lolium multiflorum Lam.) with varying levels of grain supplementation. In December, cattle were allotted to 1 of 6 treatments consisting of ryegrass pasture (1 ha) with whole shell corn supplemented at 0.0% (0.0), 0.5% (0.5), 1.0% (1.0), 1.5% (1.5), and 2.0% (2.0) of BW, or an ad libitum mixed-ration grain diet in a drylot. Steers were randomly assigned to pens of 4 with pen serving as the experimental unit. Cattle were slaughtered by pen when average pen backfat thickness (as measured by real-time ultrasound) reached approximately 0.64 cm. Forage samples and disk meter height were taken from ryegrass paddocks on a monthly basis to determine forage quality and mass. Live animal performance, carcass traits, proximate analysis, Warner-Bratzler shear force, and sensory characteristics from the LM of the rib section were analyzed. Increasing the amount of grain in the diet of finishing cattle resulted in a linear decrease (P < 0.05) in days on feed and a linear increase (P < 0.05) in ADG, preliminary yield grade, final yield grade, flavor intensity, and beef flavor. Forage DM mass increased with each incremental increase in grain added to the grazing diets. Quality of forage was not (P > 0.05) affected by adding grain to the diet. Adding corn to the diet of cattle being finished on forage improved animal performance and decreased forage utilization characteristics in addition to improving the flavor characteristics of beef.