Abstract
The aim of this study was to evaluate the effect of pen stocking density on animal performance, social behavior, and animal and pen dirtiness in fattening bulls. Two hundred sixty-three bulls (250 ± 24.7 kg BW, and 193 ± 13.2 d age) were group-housed and fed concentrate and unprocessed straw separately, both ad libitum. Animals were assigned to one of 2 different pen stocking density treatments: 1) LOW (n=112), 14 bulls/pen (5.1 m(2)/bull and 5 bulls/feeding space); and 2) HIGH (n=151), 19 bulls/pen (3.6 m(2)/bull and 7 bulls/feeding space). The study lasted 183 d. Pen concentrate intake was recorded daily. Bulls were weighed every 2 wk. Social behaviors (from d 59) and animal and pen dirtiness (from d 120) were recorded every 4 wk. Carcass quality was recorded at the slaughterhouse. Data were analyzed with a mixed effects model. Concentrate intake was not affected by treatment, but ADG (1.57 vs. 1.47 ± 0.027 kg/d) and feed efficiency (0.21 vs. 0.20 ± 0.007 kg/kg) were greater (P≤0.05) in LOW than in HIGH. Carcass quality was similar between treatments, but preslaughter weight (552 vs. 535 ± 4.6 kg) and hot carcass weight (292 vs. 284 ± 2.9 kg) was greater (P<0.01) in LOW than in HIGH. Eating and ruminating were greater (P<0.05) in LOW than in HIGH, and lying was greater (P=0.01, treatment by time interaction) in LOW than in HIGH at d 89 and d 120. Animal dirty score was lesser (P≤0.01) in LOW than in HIGH (0.0 vs. 7.5 ± 1.33 %), and pen dirty scores were lesser (P≤0.01) in LOW than in HIGH in d 120. In conclusion, decreasing pen stocking density by 42 % improves animal growth and efficiency, behaviors indicative of greater welfare and comfort, and cleanliness in fattening bulls.