The influence of weight classes (light, medium and heavy) of Ross chicks on performance and carcass yield and main cuts, was studied using a completely randomized design with six replicates of 30 males and 30 females each. The chicks were fed on the same diets during the growing period (1-43 days). The live weight, feed intake, feed:weight gain ratio, viability, carcass yield and main cuts (breast, whole leg, wing and back) and percentages of giblets (gizzard, liver, heart and guts) were analyzed. The heavy weight class chicks were heavier (P<0.05) than the light weight class chicks, during all the growing period and showed higher feed consumption (P<0.05) than the light and medium classes chicks. No differences among weight classes chicks concerning feed:weight gain ratio, viability, carcass yield and percentage of heart, gizzard and liver were observed (P>0.05). The males showed higher carcass yield than the females of medium and heavy weight classes chicks. The whole leg yield of heavy weight class chicks was higher than the medium weight class chicks (P<0.05). Weight class influenced live weight, feed intake, carcass yield and whole leg but had no effect on feed:weight ratio, viability, breast yield and giblets percentage.
broiler; initial body weight; performance; yield