Association of milk protein types with growth and reproductive performance of dairy heifers.

摘要: Abstract A total of 890 heifers was used to study the effects four milk protein loci ( α S1 -casein, β κ and -lactoglobulin) on heifer growth reproduction. The additive gene substitutions at were significant only in 4 56 cases for all traits studied. Dominance κ-casein not any except -casein locus body weight first calving. Heifers with AB type -lactoglobulin showed greater weights measurements gestation length than AA or BB type, indicating an over-dominance effect. significantly younger conception freshening had fewer number days from service underdominance Thus, shows over-dominance, underdominance, no dominance, depending upon considered. contributed more dominance variance phenotypic variance. This might account existence polymorphism cattle population. combined genotypes 2 14