Frequency of genetic variations associated with milk yield and composition in seven Zebu breeds

Abstract Maternal ability (milk and environment) in beef cattle is one of the most important traits influencing weaning weight of the calf, but amount and composition of milk produced by the dam is difficult to measure. The assessment of polymorphisms of candidate genes related to milk composition could indirectly enlighten this perspective. In the present study, the frequency of α s1 -casein 1175AG and g26181A>G; κ-casein 13068 ( CSN3 AB1) and 13104 ( CSN3 AB2) loci, β-lactoglobulin variants 3984GA and 5263CT, Diacyl glycerol transferase K232A, and Stearoyl CoA desaturase A702G and A762G polymorphisms were estimated in Gray and Red Brahman, Nellore, Guzerat, Gir, Indubrazil, and Sardo Negro registered sires from Mexico. Most of the documented favourable alleles were found in low frequency in most of the evaluated breeds, except for β-lactoglobulin, in which the presence of favourable alleles might represent an opportunity for marker-assisted introgression. The relevance of the findings for each variation and implications from the outcomes are discussed.