Effects of duration of feed restriction on carcass composition of Leghorn cockerels

To study effects of duration of feed restriction on carcass composition of Leghorn cockerels, three-hundred sixty 7-d-old Leghorn cockerels were allotted to thirty-six pens with 10 cockerels per pen. Treatments were ad libitum consumption of feed (AL) or feed intake was restricted to 80% of ad libitum intake for two (R-2), five (R-5), or eight (R-8) wk, followed by ad libitum feeding for the remainder of the experiment. Nine birds per treatment were slaughtered when mean body weight (BW) within a treatment was 250, 500, 1000 and 1310 g. At 250 g BW, carcass protein concentration was lower (P<0.01) and carcass fat concentration was greater (P<0.01) for birds in the AL and R-2 feeding regimens compared with birds in the R-5 and R-8 regimens. At 1310g BW, there were no significant (P>0.33) treatment effects on carcass protein and fat concentrations. Carcass protein concentration and protein accretion rate appeared to be affected more by body weight than feeding regimen. Carcass fat concentration and accretion rate decreased during a feed intake restriction period, but rapidly increased during realimentation.