Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/3/2006
Publication Date: 7/10/2006
Citation: Dozier III, W.A., Thaxton, J.P., Purswell, J.L., Olanrewaju, H.A., Branton, S.L., Roush, W.B. 2006. Stocking desnsity effects on male broilers grown to 1.8 kilograms of body weight. Poultry Science. 85:344-351. Interpretive Summary: Animal welfare has generated concerns from both domestic and global market sectors in marketing meat products of broiler chickens. Stocking density in growout has been regarded as a concern to food retailers and wholesalers. High stocking density has been reported to increase ammonia production, foot pad lesions, litter moisture, locomotion, heat stress, and preening. This study evaluated growth responses, stress hormone concentrations, and processing yields of male broilers to four stocking densities. Results indicated that increasing stocking density from 25 to 40 kg BW/m2 of floor space affected BW gain, feed consumption, and meat yields. Cumulative BW gain and breast meat yield decreased 41 and 12 g, respectively, for each 5 kg BW/m2 unit increase in stocking density. Stress hormone concentrations were not affected by stocking density.
Technical Abstract: This study examined the effects of stocking density on live performance, physiological stress indicators, and processing yields of male broilers grown to 1.8 kg. A total of 3,120 Ross x Ross 708 male chicks was placed into 32 floor pens (5.57 m2/pen). Stocking density treatments were 25, (75 birds/pen), 30 (90 birds/pen), 35 (105 birds/pen), and 40 (120 birds/pen) kg BW/m2. From 1 to 35 d, BW gain, feed consumption, and feed conversion were adversely affected with increasing stocking densities. Physiological stress indicators (plasma corticosterone, glucose, cholesterol, total nitrites, and heterophil:lymphocyte ratio) were not affected. Litter moisture increased as stocking density heightened, which led to a higher occurrence of foot pad lesions. In parallel to growth responses, carcass weight was oppressed by increasing stocking density, but carcass yield, absolute and relative amounts of abdominal fat, and carcass skin defects were not affected. Increasing stocking density decreased breast fillet weight and its relative yield and breast tender weight, but not breast tender yield. As calculated stocking density increased 5 kg BW/m2 beyond 25 kg BW/m2, final BW and breast fillet weight were decreased by 41 and 12 g, respectively. We conclude that increasing stocking density beyond 30 kg BW/m2 adversely affects growth responses and meat yield of broilers grown to 1.8 kg, but does not alter physiological stress indicators.