Stocking density effects on growth performance and processing yields of heavy broilers

This study examined responses of male broilers during a 49-d production cycle to 4 placement densities in 2 trials. Trials were pooled because no treatment x trial interaction occurred. In each trial, 1,488 male chicks were randomly placed into 32 floor pens to simulate final densities of 30 (37 chicks/pen), 35 (43 chicks/pen), 40 (50 chicks/pen), and 45 (56 chicks/pen) kg of BW/m(2) 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 of BW/m(2) 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/m(2). 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/m(2) elicited some negative effects on live performance of heavy broilers.