Effects of Dietary Supplementation of a Mixture of Synbiotic and Some Digestive Enzymes on Performance, Behaviour and Immune Status of Broiler Chickens

摘要

This study aimed at studying the effects of a mixture of synbiotic and some feed enzymes (Avi-bac?) on broiler chickens performance, behaviour and immune status. Two hundred and twenty five 1-d-old chicks (Hubbard breed) were randomly distributed into three treatment groups (3 replicates each) using 25 chicks/replicate on floor pens. Control (C) birds were offered non-supplemented basal diets. Treatments 1 and 2 (T1 and T2) were fed diets containing Avi-bac? 250 and 500 g/ton feed respectively. Feed and water were offered ad-libitum for 35 days experimental period. Feed consumption and body weight were recorded weekly to calculate body gain and feed conversion. Feeding, drinking and resting behaviour were observed. Blood samples were collected by time intervals to evaluate the immune status of the birds against some vaccines and to evaluate the stress conditions. At the end of the experimental period 9 birds were chosen randomly from each group to compare carcass yield. The results showed that body weight was significantly (p<0.05) improved in chicks fed on Avi-bac? containing diets compared with control ones. Supplementation of diets with Avi-bac? increases significantly feed intake (p<0.05) and improved feed conversion. The best feed conversions were recorded in supplemented groups. Dressing percentage and liver weights were non-significant differ between groups. However, abdominal fat content was reduced significantly (p<0.05) in both supplemented groups. Birds in supplemented groups recorded low level of cortisol and H/L ratio. Supplementation of the broiler diets was significant enhance immune responses measured against vaccines used. It can be concluded that, using mixtures of synbiotics and digestive enzymes act synergistically as feed additives and reflected positively on zootechnical performance of broiler chickens, reduce stresses and enhance immune status.