Effects of early growth rate and fat soluble vitamins on immune function and their share in intra-flock variability in production performance indices in broiler chicks

A ۷× ۲ factorial experiment was conducted to evaluate the effects of early growth rate (x̄- ۳SD, x̄-۲SD, x̄-۱SD, x̄, x̄+۱SD, x̄+۲SD and x̄+۳SD) and a fat soluble multi vitamin mixture (FSVM, ۰ and ۱.۲ ml/ bird) on immune-related parameters and their share in intra-flock variance of performance indices using ۳۶۲ male Ross ۳۰۸ broiler chicks. Body weight (BW) at marketing age (۴۲d) was differed among the birds in the same pattern as their BW at day ۲۱ of age. The birds receiving a FSVM gained greater body weight, consumed more feed and utilized the feed with a greater efficiency than the untreated birds. Mean serum antibody titer against Influenza at day ۴۲ of age was greater in the birds with initial body weight of ۲ and ۳ SD more than population mean at age of ۲۱ day. Neutrophil count and heterophile to Lymphocyte ratio (H/L) were significantly increased in the birds receiving the vitamin cocktail by ۲.۵ and ۳ fold, respectively (P<۰.۰۵). No routine immune-related parameter including immunobiological organs weight (excepting spleen percentage), antibody titers and WBC differential counts were generally not able to explain a considerable fraction of the variance exhibited in a broiler flock.

کلیدواژه ها:

Broiler chick ، Early growth rate ، Fat soluble vitamins ، Immune function ، Production performance.