Two experiments were conducted with male broiler lines to investigate the effect of genotype and level of protein on thier growth,feed conversion and carcass quality .Four isoenergetic dietes(ME 3200 Kcal/Kg) with different levels of crude protein 19,21,23,25 and 16,18,20,22 % were formulated and fed the chicks for 0-3 and 3-6 weeks, respectively .The A and B lines from Babolkenar broiler line were used as genotype.
In the first experiment 448 male and female day -old chicks from A and B lines were reared separately in cold batteries for 6 weeks. In the second experiment 1344 male and female day - old chicks from A and B lines were reared on floor for 6 weeks.
In both experiments B line chicks had better performance (highest body weight, low fat deposition and better feed conversion) when the chicks were fed the ration with the highest level of protein , while A line chicks had better performance with the third level of protein.
The results of the present experiments, also suggested that genotype, levels of protein in the ration and their interaction have effect on different traits.Interaction between line and dietary protein levels was significant (P<0.05) as far as the final body weight was concerned.
The results of this study indicated that the levels of protein had a positive significant (P<0.01) effect on feed conversion and body weight at 6 weeks of age.Final body weights were increased as The dietary level of protein were increased .In the second experiment by increasing dietary level of protein , breast and sartorial percentage were increased (P<0.05), whereas percentage of abdominal and caraass fat were decreased (P<0.01) the carcass moisture was inversely related to carcass fat. Body weight of the B line chicks was heavier than A line chicks (P<0.01), also feed conversion rate of the B line was better than A line.
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