Etude de l'efficacité de serocolostrums bovins sur le transfert de l'immunité passive du poulain

The failure in passive transfer of maternal antibodies present in colostrum leads to a rate of mortality close to 10 to 12% by current infections. One of the main reasons responsible for this failure is the lack of good immunological quality colostrum with high immunoglobulin (IgG) concentrations. In this work, three different bovine serocolostrums with high immunoglobulin concentrations were given to foals, either in substitute or in association with an equine colostrum with low immunoglobulin levels, during the 7 hours after foaling. The bovine and equine IgG levels in serum were followed, the IgG absorption coefficient and the half-time of IgG were calculated and the animal diseases were followed. Only one bovine serocolostrum allowed to get an IgG level in foal serums higher than 8 gkh-1 at 24 hours old with an IgG concentrations in serum of 12 to 16 gkg-1. A specific peptidic fraction of this serocolostrum could play a role in the IgG transfer through the immature intestinal epithelium. The bovine serocolostrum does not avoid specific infections with Rhodococcus equi but these infections have been absolutely recovered by adapted antibiotic treatment. The half time of bovine IgG (4-5 days) is shorter than the equine ones (24 days) but the fast decrease in bovine IgG seems partially being compensated by the earlier endogeneous production of the foals. This study showed that the bovine serocolostrum given in association with a poor equine colostrum could be able to limit the failure in passive transfer.