Effect of decreasing dietary protein levels with optimal aminoacids profile on the performance of broilers

A six-week trial was conducted to study the effect of decreasingdietary crude protein (CP) level on the performance of broilers inhot climatic conditions. Four experimental rations having CP 23(control group), 22, 21 and 20%, with optimal amino acid balance wereprepared. All the four rations were isocaloric having ME 3200kcal/kg with Energy: Protein (E:P) 139.0, 146.5, 152.4 and 160 indiets A, B, C and D respectively. One hundred and twenty day-oldchicks were randomly distributed into 12 experimental units, eachhaving 10 chicks. Rations were randomly allotted to experimentalunits such that each unit received three replicates. The experimentaldiets were fed to birds from day 1st to 42nd. Performance of birdswas monitored in terms of weight gain, feed consumption and feedconversion ratio (FCR). At the end of experiment, two birds per eachreplicate were randomly selected and slaughtered to record the dataon carcass yield, breast meat yield, abdominal fat and composition ofbreast meat. Results of the trial suggested that weight gain wassignificantly (P less than 0.01) increased in birds on diets with CP20 and 21%. Feed consumption and FCR remained un-changed for allthe treatment groups. Eviscerated carcass yield was significantly (Pless than 0.05) higher for the group fed on diet with 20% CP. Breastmeat yield, abdominal fat and composition of breast meat alsoremained un-changed. Economic evaluation of the trial revealed thatdecreasing CP levels from 23 to 20% resulted in reduced feed costper kg of live weight gain, which clearly indicated that thisapproach was useful especially in severe summer conditions. Theoverall picture of the study suggests that dietary protein level ofbroilers could be reduced from 23 to 20%, with beneficial effects ongrowth performance and carcass characteristics and increasedeconomic returns in hot environmental conditions, provided thatlevels of essential amino acids are closely looked after.