Restricted Feeding in Broiler Chickens - Effect of Age at Initiation and Severity on Performance

Abstract

A completely randomized experimental design with a 4 x 3 factorial arrangement of treatments was conducted in order to investigate the effect of age and level of feed restriction on the performance and carcass quality of broiler chickens. The two main effects investigated were age of initiation of feed restriction at 4 levels (7, l4, 28 and 35 days) and the level of restriction at 3 levels (10%, 20% and 30%). One positive control (no restriction at any age or level) was used to compare with the other experimental treatments. A total of 468 day old broiler chicks were equally and randomly distributed among 39 pens, each measuring lmc and lm high. Quantitative feed restriction commenced at 7, 14, 28 and 35 days and lasted 2 wk after which birds resumed full feeding upto the end of the study period (56 days). The performance of the broiler chickens was evaluated during the 2 wk restriction period, 2 wk recovery period and finally at 56 days. The variables evaluated were feed intake, feed efficiency, body weight, average gain, carcass quality and mortality rate. All broiler chickens subjected to feed restriction had significantly (P<.O5) lower mean body weights than the controls, with those restricted at 7 days having the lowest v final body weight at 56 days. During the 2 wk restriction period feed efficiency was higher (P<.O5) for the restricted birds in all the groups but there were no significant differences (P>.O5) between the controls and the restricted groups at the end of the enperiment (56 days). Restricted birds had significantly (P<.O5) higher rates of gain than control groups during the recovery period but compensatory growth was only partial since all restricted birds had lower final body weight than the control birds. Interaction between age of restriction and level of restriction was not significant (P>.O5) for all variables measured except for feed intake where broiler chickens restricted during the finisher period and at 30% had significantly (P<.O5) lower intakes compared with the other feeding regimens. Restriction had no effect on overall mortality at the end of the study (56 days). Feed restriction significantly (P<.O5) depressed carcass weight and abdominal fat regardless of age or level. There were no significant differences (P>.O5) among restricted groups for all carcass variables measured. From this study, it was evident that feed restriction reduced abdominal fat in broiler chickens, and saved on feeding costs.