Immune response of growing crossbred (Bos taurus x Bos indicus) calves fed isonitrogenous grainless diet

The effect of grainless/low grain diet on immune response was studied by taking 5 month-old male crossbred calves (25). The calves were divided in 5 groups, viz. S1,S2,S3,G2 and G3 of 5 calves in each group where calves in group S1 (control) received a conventional maize grain based concentrate mixture. The maize moiety was replaced by 50% in groups S2 and G2 and by 100% in S3 and G3. Calves in groups S1,S2 and S3 were offered ad lib. wheat straw and those in groups G2 and G3 were offered green sorghum fodder ad lib. from 20 week of age. At 26 weeks of age, all the calves were vaccinated with Pasteurella multocida (P-52 strain) and blood was collected at 0,7,14 and 28 days of post vaccination period. Both cellular and humoral immune responses were observed. All cellular components (TLC and DLC) were found in normal range in all the groups during post vaccination periods. The antibody level of zero day was not detected by STAT (standard tube agglutination test) but could be detected by ELISA (enzyme linked immunosorbent assay) indicating presence of maternal antibody. The antibody level as detected by STAT and ELISA during post vaccination periods (7,14 and 28 days) showed a rise from 7th day onward and continued to increase up to 28th day. The albumin :globulin ratio (A:G ratio) increased in post vaccination periods. Study indicated the partial or complete replacement of cereal grain with wheat bran had no significant effect on the immunity of crossbred calves.