Substitution of corn grain with white oat grain in non-forage diets for feedlot beef cattle

ABSTRACT This study evaluated the substitution of corn grain with white oat grain in finishing yearling bulls (initial weight of 259.4±31.7 kg and 18.0±0.2 months of age). The experimental design was completely randomized. The substitution levels of corn grain for white oat grain were 0, 25, 50, 75, and 100%. Diets comprised 85% of grains + 15% of a protein-vitamin-mineral pelleted supplement. The adaptation program consisted of ad libitum feeding of five diets over the adaptation period of 14 days, with the concentration level increasing from 60 to 100% of the diet on a dry matter basis. Daily weight gain and carcass gain presented a quadratic behavior with the inclusion of white oat grain. As a result of the differences in average daily gain, the feedlot period varied among groups until the target slaughter weight was reached. Dry matter intake, nutrient intake, feed efficiency, and Kleiber ratio presented a quadratic behavior. Ingestive behavior and rumination patterns were modified by the levels of white oat grain, with longer rumination time observed with the combination of grains. A similar response was observed for the number of regurgitated and chewed bolus. Conversely, the number of chews per bolus and the chewing time per bolus increased linearly with the replacement of corn with white oat grain. Residual intake and body weight gain and the participation of heart, lung, and kidney, heart, and pelvic fat g kg−1 of empty body weight decreases linearly with the inclusion of white oat grain. The partial substitution of corn grain with white oat grain improves the productive performance and rumination patterns yearling bulls in feedlots receiving non-forage diets.