QUDRATULLAH, S(MAJOR)Chinni Preetham, VRaju, M.V.L.NReddy, M.RSRINIVAS, G2018-11-012018-11-012010-06http://krishikosh.egranth.ac.in/handle/1/5810082684THESESABSTRACT : The aim of the present study was to investigate the effect of dietary supplementation of a probiotic, a prebiotic and an acidifier either individually or in combination for comparing the performance and immune status of broiler chickens with antibiotic and control. For this purpose, 270 day-old commercial male broiler chicks were randomly divided into 9 treatment groups with 6 replications of 5 birds each. The experimental design consisted of; a control diet (maize-soya based) without supplementation, Antibiotic (Virginiamycin @ 500 g/ton), Probiotic (Protexin @ 500 g/ton), Acidifier (Biotronic SE @ 3 kg/ton), Prebiotic [Mannanoligosaccharide (Mos) 500 g/ton], and combinations of Probiotic + Acidifier, Probiotic + Mos, Acidifier + Mos, Probiotic + Acidifier + Mos at their respective inclusion rates. The broilers were fed with prestarter (0-14 d), starter (15-28 d) and finisher diets (29-42 d). The birds were maintained under similar management conditions in battery brooders. The feed and water were offered ad libitum. The ANOVA indicated that body weight gain of broilers was significantly (P<0.05) influenced by all dietary treatments in comparison to control and antibiotic throughout the course of the study. Acidifier alone had significantly (P<0.05) higher body weight (2059 g) gain followed by probiotic + Mos combination (2039 g) during the overall experimental period (0-42 d) compared to control and antibiotic treatments. No significant (P>0.05) difference was recorded among other groups at 42 d of age except probiotic + acidifier group (1939 g) which recorded the lowest body weight gain. During the overall experimental period, no significant (P>0.05) difference was observed on feed intake with all the treatment groups. But, feed efficiency was significantly (P<0.05) improved in all test groups during the overall experimental period compared to control. No significant (P>0.05) differences were observed among probiotic, acidifier, Mos, acidifier + Mos, probiotic + Mos, probiotic + acidifier, probiotic + Mos + acidifier and antibiotic groups which ranged from 1.62 to 1.67 compared to control diet (1.71). All dietary supplements did not have significant (P>0.05) effect on various carcass parameters studied, except for abdominal fat percentage, which was significantly (P<0.05) lower in probiotic, acidifier alone and acidifier + Mos groups at 42 d of age, while the rest of the treatment groups did not differ from control. Mortality was less and in normal range in all the dietary treatment groups. The bursa and spleen weights were significantly (P<0.05) influenced by all dietary treatments. Bursa weight was significantly (P<0.05) high in probiotic, acidifier alone and combination of probiotic + Mos + acidifier groups, similarly higher spleen weight was noticed in Mos alone and probiotic + Mos + acidifier combination in comparison to control. The humoral immune response to SRBC was increased significantly (P< 0.05) in all dietary treatments compared to control at 42 days of age. The higher titer values were recorded in Probiotic + Mos + acidifier combination group followed by acidifier alone and acidifier + Mos. Supplementation of probiotic, Mos and acidifier either alone or in combination did not have any significant (P>0.05) influence on the cell mediated immunity in terms of CBH response, but higher CBH response was noticed in all test diets compared to control. Supplementation of all dietary feed additives significantly (P<0.05) reduced the E. coli counts in the small intestine compared to control at 42 d of age. The lowest E. coli counts were recorded in probiotic, acidifier alone and probiotic + acidifier + Mos groups, whereas the other groups showed intermediate E. coli counts. Supplementation of all dietary feed additives (except probiotic + acidifier group) yielded higher returns over feed cost than the control and antibiotic groups. The highest return per bird was recorded with acidifier (Rs.4.96 / bird) followed by probiotic + Mos (Rs.4.54 / bird) groups.ennullThesis