|Dozier iii, William|
Submitted to: Poultry Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/24/2005
Publication Date: 8/15/2005
Citation: Dozier III, W.A., Thaxton, J.P., Branton, S.L., Morgan, G.W., Miles, D.M., Roush, W.B., Lott, B.D., Vizzier-Thaxton, Y. 2005. Stocking density on growth performance and processing yields of heavy broilers. Poultry Science. 84:1332-1338. 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 and processing yields of male broilers to four stocking densities. Results indicated that increasing stocking density from 30 to 45 kg BW/m2 of floor space affected BW gain and feed consumption more dramatically than meat yields. Cumulative BW gain decreased 64 g for each 5 kg BW/m2 unit increase in stocking density.
Technical Abstract: This study examined responses of male broilers during a 49-d production cycle to four placement densities in two trials. Trials were pooled because no treatment x trial interaction occurred. In each trial, 1,488 male chicks were randomized to 32 floor pens to simulate a final densities of 30 (37 chicks per pen), 35 (43 chicks per pen), 40 (50 chicks per pen), and 45 (56 chicks per pen) kg BW/m2 of floor space based on a projected final BW of 3.29 kg. Growth rate and nutrient utilization were similar (P ' 0.05) among the treatments from 1 to 32 d of age. From 1 to 49 d, BW gain (P=0.011) and feed consumption (P=0.029) were adversely affected by increasing the placement density from 30 to 45 kg BW/m2 of floor space. The reduction in cumulative BW gain due to placement density can be partially explained by less feed consumption as evidenced by 95.4% of the sums of squares of BW gain being attributable to feed consumption. Litter moisture content (P=0.025) and foot pad lesion score (P=0.001) increased linearly with increasing placement density. Upon processing, whole carcass and breast meat yields relative to BW were not affected (P'0.05) as density increased from 30 to 45 kg/m2. The proportion of whole carcasses with scratches, but not tears, on the back and thighs increased (P=0.021) as density increased. These results indicate that increasing the density beyond 30 kg/m2 elicited some negative effects on live performance of heavy broilers.