the effect of different levels of vitamin premix within the last three weeks of rearing period on performance and carcass characteristics of broiler chicks

the present experiment was conducted to evaluate the effects of different levels of vitaminpremix(vp), fed during the last three weeks of a broiler rearing period (22-42 days), on its growthperformance and carcass characteristics. four hundred 22 day old broilers received diets containingfour levels of supplementary vp (0, 33.33, 66.66 and 100%) each at a different weeks of finisherperiod. the diets were formulated as based on wheat and soybean meal, with the experimentconducted on floor pens of 10 treatments and 4 replicates in a completely randomized design. thedietary treatments consisted of: t1 no vp supplement during 22 to 42 days of age; treatments 2, 3and 4 containing 33.33% vp,. treatments 5, 6 and 7 with 66.66% of vp supplement and finallytreatments 8, 9 and 10 containing 100% of vpsupplement. the treatmeants were so arranged that t 2,5 and 8 received only from 22 to 28; treatments 3, 6 and 9 only from 22 to 35, and treatments 4, 7 and10 only from 22 to 42 days of age. the results finally indicated that vp reduction and withdrawal at 22days of age did not impair the birds, performance during their last three weeks of rearing period (22 to42 days). decrease in the level of vp did not significantly affect the carcass characteristics (carcassyield, percentages of breast, thigh, liver, heart as wellas abdominal fat).