Nutrient intake, feeding patterns and abnormal behavior of growing bulls fed different concentrate levels and a single fiber source (corn stover silage)

Abstract Twenty-eight bulls weighing 227±6.8 (SD) kg were randomly assigned to four concentrate levels (1-1.5 kg (LC), 1.5-2 kg (MC), 2-2.5 kg (HC), and 2.5-3 kg (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 trend of acid detergent fiber (ADF) and neutral detergent fiber (NDF) intake, whereas the decreasing (P trend of ADF and NDF intake was observed when concentrate level was increased from HC to H + C. The longest (P time required to consume the concentrate was observed in the H + C treatment, whereas the lowest time (P required to consume the concentrate was observed in the LC treatment. The highest (P silage consumption was observed for the LC treatment at 16:00 (26 minutes). Chewing was highest (P at 04:00 and 18:00 for the H + C treatment. The LC bulls showed longer (P lying behavior during 18:00 and 24:00 compared to other groups. Abnormal behavior was maximum (P 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.