Influence of casein haplotypes on quantitative traits in milk of Braunvieh and Fleckvieh in Switzerland
1997
Braunschweig, M. | Puhan, Z. (Swiss Federal Inst. of Technology, Zurich (Switzerland). Lab. of Dairy Science)
The objective in this study was to estimate the substitution effects of chromosome sections within sires of the breed Braunvieh (BV) and the crossbreed Simmental x Red Holstein with different percentages of Red Holstein blood. In Switzerland, the latter breed is summarized under the name Flechvieh (FV). A few sires of each breed with the same two heterozygous haplotypes at one locus were selected. Their daughters were assigned, if possible, also with the information of their mothers into two groups according to the casein haplotype they received from the father. The aim was to verify whether the haplotypes can be used as markers for certain production traits across families, and also, to estimate the difference between two alleles of a casein gene presumed as a quantitative trait locus (QTL) or closely linked to such a QTL. The study was done under the assumption that all other influences are equally distributed across the groups within the same breed. Haplotypes of dams and the beta-lactoglobulin (beta-Lg) genotype were also taken into consideration. For both breeds BV and FB the influence of beta-Lg genotypes on whey protein content was highly significant (AA greather than AB greater than BB). Also for Braunvieh, the casein content was found to be significantly influenced by beta-Lg genotypes (BB greater than AB greater than AA). According to the results presented here, one of the two paternal haplotypes is not always superior or inferior for a certain trait and, therefore, the casein haplotype can not be used as a marker. Further investigations are required to determine whether mutations can be detected in the regulatory regions of the gene to explain the inconsistency. Should this not be the case, the suggestion of the existence of at least one gene very closely linked to a casein gene is more likely to influence the protein content of the milk.
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