Feeding regimen, dietary vitamin E, and genotype influences on immunological and production traits of broilers

Many functional changes occur during the first 2 wk after a broiler hatches , a period that continues to be an increasing proportion of a broilers life . Breeding programs are designed to produce a broiler with high potential f or growth, yield, and feed efficiency, traits that may compromise health st atus under husbandry designed to maximize this genetic potential. this expe riment compared performance of two broiler lines differing in growth and yi eld, when reared to 12 days of age under full and diluted feeding regiments containing three dietary levels of vitamin E. Traits measured included bod y weight (BW), feed efficiency, and allomorphic measures of breast, shank, spleen, bursa, heart, gizzard, ceca, and lung. For bilateral traits, asymme tries were measured. Data were obtained for mortality, response to sheep re d blood cell antigen, heterophils, lymphocytes, and response to an E. coli challenge. Responses to dietary feed restrictions and levels of dietary vit amin E during the first 12 days after hatch were noted at market age. There was a trade-off between growth- and health-related traits with responses t o husbandry programs, age, sex, and genetic line.