Effects of hay grass level and its physical form (full length vs. chopped) on standing time, drinking time, and social behavior of calves

Two 73-day experiments were done on growing calves to evaluate the effect of different forage particle length of hay grass on standing time, drinking time, and social behavior. Hay grass level was changed by increasing and decreasing forage to concentrate ratio (F:C). Hay was the only source of fiber in the diet. In experiment 1, F:C were fed at full length (FL) hay in the total mix ration: low F:C (50% forage) with FL, high F:C (65% forage) with FL. In experiment 2, calves were fed the same total mix ration with same ingredients and nutrient composition but differing in particle length of hay: treatments were lower F:C (50% forage) with short length and higher F:C (65% forage) with short length. At the end of second month, 1 week of adaptation period was provided to allow adjustment of social and feeding behavior with pen mates. Four color cameras supported with infrared antinozzle technology were used to record standing, drinking, and social behaviors. In experiment 1, treatment and hour interaction was found for standing time (P < 0.05). Longer standing time was observed for the ninth hour after feed delivery. Animals with low F:C showed longer standing time as compared with high F:C (P < 0.05). Social behavior was altered with hour of observation (P < 0.05). Social activity was highest during the first to third and ninth hours after feed delivery. In experiment 2, standing time was affected by hour of observation in both treatment groups (P < 0.05). Drinking water intake was affected by dietary treatment (P < 0.05). Longest drinking time was observed in the low F:C group. Social activity was highest during first to second and ninth hours after feed delivery (P < 0.05). This study suggests that forage level should be carefully considered to promote normal behavior and positive welfare especially during the growing phase of fattening calves.