THE INFLUENCE OF EXTENDED POSTHATCH HOLDING TIME AND PLACEMENT DENSITY ON BROILER PERFORMANCE

Extended posthatch holding (in the hatcher) has been reported to dehyd rate chicks, reduce broiler performance, and depress immune response. Nevertheless, some commercial hatcheries are increasing incubation tim e in an attempt to minimize possible bacterial contamination of incomp letely healed navels. The objectives of this study were to determine t he effects of posthatch holding on broiler performance and the effects of bird density and additive stress on performance and immune respons e. Twelve hundred broiler eggs (58 to 70 g) were incubated. Chicks wer e removed from the hatcher after 528 h of incubation, banded, and weig hed. Half of the chicks were returned to the hatcher for an additional 24 h (HELD). Both hatcher treatments were placed at two densities (.0 7 and .12 m(2) per bird). Individual BW were taken at 21 and 43 d of p lacement and 43 d of age. The HELD chicks weighed significantly less t han controls at time of placement. At 21 d postplacement the HELD broi lers were significantly heavier than controls, but were similar by 43 d. Total feed conversion was not affected in the HELD treatment, but b irds in the .07 m(2) per bird density were less efficient in terms of total feed conversion. Chick holding time and density seemed to affect antibody titers at 5 wk. Although holding chicks in the hatcher for 2 4 h did not clinically dehydrate chicks or affect performance, it decr eased immune response. In addition to less efficient growth, birds in the more crowded pens had depressed immune response.