EFFECTS OF THE ALPHA-S1-CASEIN POLYMORPHI SM ON GOAT DAIRY PERFORMANCES - A WITHIN-SIRE ANALYSIS OF ALPINE BUCKS

The effects of the main alleles at the goat alpha(s1)-casein locus (al pha(s1)-Cn(A,B,C,E,F) called A, B, C, E, F) on milk production traits were estimated via a within-sire analysis of the progeny of 5 Alpine b ucks. This polymorphism had no effect on milk yield. On the other hand , compared with the weak F allele, the strong alleles A and C had a si gnificant effect on the true protein content (+2.5, +2.6 and +1.8 g/kg for 3 families), the fat content (+ 1.5, +2.2 and + 1.1 g/kg) and the true protein yield (+2.3, +2.0 and +1.5 kg). Compared with the interm ediate E allele, the strong A allele had a significant effect on the t rue protein content (+2.0 g/kg) and the fat content (+2.6 g/kg). The r esults on the true protein content were in agreement with previous est imates of the effects of the same alleles on the casein content of mil k.