Comparison of milk production of the progeny of BLAD-carrier and healthy Holstein bulls in Hungary.

'Bovine Leukocyte Adhesion Deficiency' (BLAD) is a recessive monofactorial, lethal inheritable defect occurring in Holstein-Friesian cattle and often passed on by well-known top bulls. The aim of this study was to find a relationship between the BLAD genotype of bulls, their genetic evaluation for milk and their daughters' milk production. BLAD-carrier and healthy bulls were compared on the basis of their breeding value published in November 1997. The first 100 bulls ranked according to the Total Production Index (TPI) were used, including nine BLAD carriers with 2,835 daughters and 77 healthy sires with 21,950 female progenies. For 14 bulls the BLAD genotype was not indicated. The healthy animals significantly outperformed the BLAD carriers, which result contradicts our earlier findings (Dohy et al., 1996; Jánosa and Dohy, 1997). In a BLAD elimination programme, the identification of BLAD carriers and properly planned mating are of great importance in order to avoid 'inter se' mating of BLAD-carrier top animals which can be of significant influence in Holstein breeding.