Effects of grain source, silage level, and slaughter weight endpoint on growth performance, carcass characteristics, and meat quality in Angus and Charolais steers

Two growth performance trials were conducted to evaluate the effects of grain source (corn vs. barley), com silage level (15 vs. 50%) and body weight (BW) at slaughter on growth performance, carcass characteristics, and beef quality. Gains were greater (P < 0.01) feeding corn vs. barley to Angus cattle slaughtered at 550 or 600 kg, most likely due to greater (P < 0.02) feed intakes for corn-fed cattle. Despite greater dry matter intake (DMI; P < 0.01) and feed to gain ratios (P < 0.08) with 50% silage diets, cost of production was lower (P < 0.01) feeding 50 vs. 15% silage diets. Grain source by BW endpoint interactions (P < 0.06) were present for Angus steers due to greater average daily gain (ADG) and lower feed to gain and cost of production in corn-fed cattle slaughtered at 600 versus 550 kg, while the converse was the case for barley-fed cattle. Carcass characteristics and palatability attributes were generally not affected (P > 0.05) by grain source or silage level in the diet. Grain source by silage level by slaughter endpoint interactions (P < 0.08) were present for measures of tenderness (shear force and taste panel assessment of tenderness, chewiness, and rate of breakdown). Gains were not affected (P > 0.27) by grain source for Charolais cattle, while barley feeding decreased (P < 0.10) DMI, feed to gain, and costs of production versus corn feeding. Silage level in the diet did not affect (P > 0.10) any growth performance trait in Charolais cattle. Grain source generally did not affect (P > 0.10) most carcass characteristics and shear force with the Charolais steers. The feeding of the 15% silage diet decreased (P < 0.10) measures of leanness and muscling. Many carcass characteristics were affected (P < 0.02) by slaughter endpoint in Charolais steers, with values changing as BW at slaughter increased from 600 to 700 kg.