Analysis of the immune response to the Bovine Viral Diarrhoea (BVD) virus in the colostrum and calf blood. The influence of the maternal vaccination in the pre-partum period.

Abstract

The general objective of this project is to evaluate the immune response to the BVD virus in the bovine colostrum and blood of neonate calves, as well as verify the importance of the maternal vaccination to the BVD virus in the pre-partum period. For that, 2 groups will be formed by 5 calves and their respective mothers each. The first group (G1) is going to receive colostrum of unvaccinated cows. The second group (G2) is going to receive colostrum of vaccinated ones. Immediately after the parturition, mothers will be separated from their calves, so we can take the samples of the colostrum. Then, both groups (G1 and G2) will receive 4 liters of fresh colostrum, divided in 2 meals, with a gap of 8 hours between them. The first one will be given 6 hours after the parturition. On the following days, all animals will receive milk (10% of their weigh a day), divided in 2 meals by artificial feeding. Samples of the calves blood will be taken before they take the colostrum (T0) and on 2nd, 4th, 6th, 8th, 10th, 15th, 30th, 60th, 90th, 120th, 150th, 180th days postpartum. The samples of the colostrum and blood will be submitted to centrifugation so we can obtain the serum and the supernatant of the colostrum, used to quantify specific antibodies to BVD virus by the immunoenzymatic test (ELISA) and neutralization of the serum. The distribution of data will be evaluated by the Kolgomorov-Smirnov test. If they present a parametric distribution, they will be submitted to an analysis of variance and their averages will be confronted by the Duncan test. The variables with nonparametric distribution will be compared by the Mann-Whitney test.