Blood typing results from 138 cows of a Gir herd, selected for milk production and submitted to preferential matings by approximately 30 years, were studied to verify association among the B, F, J, L and Z blood factors or phenogroups and the first lactation milk yield. Significant differences were found between the animals with the Z blood factor, 3634.43kg (P<0.001), and the ones without Z, 3074.62kg (P<0.05). For the B blood group system, by mean contrasts, significant differences were observed between the homozygous animals for the phenogroup I1O1Y2A’B’E’3(J’K’)P’Q’, 4202.86kg (P<0.05) and the heterozygous animals for the phenogroups B(P)QTE’3G’P’/ I1O1Y2A’B’E’3(J’K’)P’Q’, 3493.33kg (P<0.05,) and BQTA’B’I’(P’)/ I1O1Y2A’B’E’3(J’K’)P’Q’, 3630.36kg (P<0.05).
Bovine; Gyr; phenogroup; milk yield
