Desempenho e rendimento de carcaça de frangos submetidos a restrição alimentar na fase inicial, em diferentes sistemas de criação

Abstract

To verify the effect of feed restriction at the initial phase of rearing upon the performance and carcass yield, 702 one-day old broiler chicks of both sexes with average weight of 43g in an experiment conducted in the poultry sector of the Department of Animal Science at the Lavras Federal University. The experiment with length of 42 days was in completely randomized design,3x3 factorial (rearing system and restriction program), with 3 replicates and 26 broilers in each plot. It was used Tukey's test to evaluate differences among treatments. The restriction programs were: 1-consumption ad libitum through out the experimental period (ad libitum), 2-fasting of 10 hours daily (from 8:00 to 18:00h) and 3-fasting of 14h daily (from 8:00 to 22:00h). The rearing systems were: males, females, and males and females reared jointly. Fasting, in both cases, was from the day 7 to 21. Body weight, feed intake, weight gain, feed conversion, viability, European production factor, carcass yield and fet pad yield were evaluated. Over the period of 7 to 21 days, both feed intake and weight gain were lower (P<0.05) in the fasting of 14h daily, but the feed conversion was not affected. From 22 to 42 days, no significant effect (P>0.05) of feed restriction programs was observed.The daily fasting 14 hour reduced both feed intake and weight gain (P< 0.05) in the period of 7 to 42 days. Body weight at 42 days of age were lower (P< 0.05) for the broilers on daily fasting program of 14 hours, in relation to the other programs (P>0.05). Viability and European production factor were better (P<0.05) for the broilers on the restriction programs submitted to fasting independent of the intensity of the restriction. The males shown better performances than the animals reared jointly or females reared separately. Restriction programs negatively affected (P<0.05) carcass yield and fat pad yield (reduced carcass yield and increased fat pad yield with the daily fasting 14 hour). The females accumulated greater (P<0.05) fat content in the carcass than the males.