effect of vitamin and mineral permixes witherawal time on growth and economic performance of broiler chickens

poultry requirments for vitamins and minerals are met from two sources feed ingredients and premixes.in practical poultry nutrition, the role of feed ingredients is over looked. this experiment was conducted to evaluate the effects of the time of vitamin and mineral premixes withdrawal on growth and economic performance of broilers. four hundred and fifty, one day-old male broiler chickens (ross 308) were used in a completely randomized design with 6 treatments of 5 replicates. chicks were fed on a common starter diet formulated based on corn and soybean meal, with common vitamin and mineral premix (vmp) levels (0. 25 % each) for the first week. then, the treatments 1 to 6 were constructed, on the basis of withdrawal time of vmp, in a way that treatment numbers were represented the number of weeks fed on vmp supplemented diet. the results showed that vmp withdrawal from 7, 14 and 21 days of age decreased daily weight gain and feed intake significantly (p