ABSTRACT

The effects of probiotic supplements and antioxidants on immune response to the Newcastle disease vaccine and performance of broiler chickens has not been investigated, especially in conditions of the stress of dry season. The study was carried out in 150 male Arbor Acres broiler chickens. The chickens were grouped into 5 of 30 broilers with 3 replicates in a group. The groups were as follows: group 1 (unvaccinated non supplemented control), group 2 (vaccinated non supplemented control), group 3 (antioxidants supplements), group 4 (probiotics supplements), and group 5 (antioxidants and probiotics). B1-strain and La Sota vaccines were administered at the ages 1 and 21 days respectively. The HI titre results at week 5, the titres of groups 1(3.6±0.8) and 2(70.4±10.5) were not significantly (P>0.05) different. Groups 3 (289.4±62) and 4(207.2±34.1) were not significantly (P>0.05) different but were significantly (P<0.05) higher than groups 1, 2 and 5(179.2±20.9). However, group 5 was significantly (<0.05) higher than groups 1 and 2. Results of the haematological study showed that the Red Blood Cell count (RBC) of groups 2(2.24±045) and 3(2.32±0.42) were not significantly (P>0.05) different but were significantly (P<0.05) higher when compared with group 1(1.75±0.89), similarly groups 4(2.78±0.56) and 5(2.96±0.63) were not significantly (P>0.05) different but were significantly (p<0.05) higher than groups 1, 2 and 3. The Total White Blood Cells (TWBC) count in group 5(33.7 × 103 ) was not significantly (P>0.05) different from groups 2(29.8 × 103 ), 3(28.6 × 103 ) and 4(37.2 × 103 ) but significantly (P<0.05) higher than group 1(20.0 × 103 ). TWBC of group 4 was significantly (P<0.05) higher than groups 2 and 3. The results showed that broilers in groups 4(2466.70) and 5(2573.30) had significantly (P<0.05) higher final weights than those in group 3(2300.00) and the control groups 1(2013.30) and 2(2110.00). Group 3 (antioxidants) broilers had significantly (P<0.05) higher final weights than those in the control groups (1 and 2). Likewise, the total weight gains in groups 4 and 5 were significantly (P<0.05) higher than those of group 3 and the control groups 1 and 2. Feed conversion ratio (FCR) of groups 1(2.70) and 2(2.62) were not significantly (P>0.05) different but were significantly (P<0.05) higher than groups 3(2.09), 4(1.69) and 5(1.45). So, FCR was best in group 5, followed by group 4, and then 3.The Benefit Cost Ratio (BCR) showed that supplemented groups; 4(1.64) and 5(1.67) had better cost benefit effects compared with the non-supplemented groups; 1(0.26) and 2(0.74). In conclusion, supplemental probiotic and antioxidants groups created better health status, improved the immune status, enhanced erythrogenesis in broiler chickens and were cost effective. The result of the study shows vaccination alone may not be adequate for the productive lives of chickens; therefore it will be advantageous to supplement broiler feeds with antioxidants and probiotics as they protected against ND infection and the chickens had mild or no lesions in the lymphoid organs. Further studies using graded levels of probiotics and for the study to be repeated in a flock of laying chickens are recommended.