ur Rahman, M. A., Xia, C., Ji, L. et al. 2019. Nutrient intake, feeding patterns, and abnormal behavior of growing bulls fed different concentrate levels and a single fiber source (corn stover silage). Journal of Veterinary Behavior 33, 46-53.
Twenty-eight bulls weighing 227 ± 6.8 (SD) kg were randomly assigned to four concentrate levels (1-1.5 kg [low level of concentrate {LC}], 1.5-2 kg [medium level of concentrate], 2-2.5 kg [high level of concentrate {HC}], and 2.5-3 kg [highest level of concentrate {H+C}]) and fed corn stover silage ad libitum. At the beginning of the experiment, the bulls in each treatment were fed 1, 1.5, 2, and 2.5 kg of concentrate, respectively, and these levels were increased by 0.25 kg at the end of each month to compensate for the growth requirements of the bulls. After three months, increases in the concentrate level from LC to HC resulted in increased (P < 0.05) trend of acid detergent fiber and neutral detergent fiber intake, whereas the decreasing (P < 0.05) trend of acid detergent fiber and neutral detergent fiber intake was observed when concentrate level was increased from HC to H+C. The longest (P < 0.05) time required to consume the concentrate was observed in the H+C treatment, whereas the lowest time (P < 0.05) required to consume the concentrate was observed in the LC treatment. The highest (P < 0.05) silage consumption was observed for the LC treatment at 16:00 (26 minutes). Chewing was highest (P < 0.05) at 04:00 and 18:00 for the H+C treatment. The LC bulls showed longer (P < 0.05) lying behavior during 18:00 and 24:00 compared with other groups. Abnormal behavior was maximum (P < 0.05) in the H+C bulls at 09:00 (17 minutes). Overall, increasing the concentrate in the diet altered specific behaviors and increased the abnormal behaviors, which could compromise the bulls' welfare.