PSXIII-3 Effect of pen Stocking Density on Animal Performance, Social Behavior, and Animal and pen Dirtiness in Holstein Bulls fed High-Concentrate Diets

Abstract The aim of this study was to evaluate the effect pen stocking density on animal performance, social behavior, and dirtiness in fattening bulls. Two hundred sixty-three bulls (250 ± 24.7 kg BW, 193 13.2 d age) were group-housed fed concentrate unprocessed straw separately, both ad libitum. Animals assigned one 2 different treatments: 1) LOW (n=112), 14 bulls/pen (5.1 m2/bull 5 bulls/feeding space); 2) HIGH (n=151), 19 (3.6 7 space). lasted 183 d. Pen intake recorded daily. Bulls weighed every wk. Social behaviors (from 59) 120) 4 Carcass quality at slaughterhouse. Data analyzed with a mixed effects model. Concentrate not affected by treatment, but ADG (1.57 vs. 1.47 0.027 kg/d) feed efficiency (0.21 0.20 0.007 kg/kg) greater (P≤0.05) than HIGH. similar between treatments, preslaughter weight (552 535 4.6 kg) hot carcass (292 284 2.9 (P<0.01) Eating ruminating (P<0.05) HIGH, lying (P=0.01, treatment time interaction) 89 120. Animal dirty score lesser (P≤0.01) (0.0 7.5 1.33 %), scores In conclusion, decreasing 42 % improves growth efficiency, indicative welfare comfort, cleanliness