Estudo das frequências dos alelos A e B dos genes da Kapa-caseína e beta-lactoglobulina e suas associações com produção de leite em bovinos F1 Girolando

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Based on choosing animals with superior phenotypes, artificial selection is traditionally used in animal breeding programs. The selection of milk cows has been exclusively based on quantitative characteristics such as milk production, which is controlled by various pairs of genes making selection a slow process. Production is also subject to the influence of ambient factors. To improve the accuracy of estimates of the animals breeding value, qualitative characteristics, such as protein types, have been investigated. The selection of individuals with genes favorable to the desired characteristics, based on their direct DNA evaluation, is called marker assisted selection (MAS). This kind of selection has the advantage that it is able to genotype the animals right after birth and for both sexes. The protein fraction of milk is comprised by various specific proteins. The most important ones are the caseins and sour protein. Some studies have associated the Kappa-casein (k-Cn) and the Beta-lactoglobulin (b-Lg) genes with milk production and quality. The results obtained are mixed, which could be related to genetic differences between and within breeds, the number of analyzed samples and the difficulties with statistical analyses. The objective of this study was to associate these markers with milk production and to establish their frequencies. Seventy F1 Girolando animals from a milk herd located in the town of Felixlândia in Minas Gerais state were genotyped, with the objective of associating these markers with milk production and establishing their genotypic and genic frequencies. The results showed that 80% of the animals had AA genotype and 20% AB for k-Cn. The gene frequency was of 90% of A and 10% of B. The BB genotype did not appear in these samples. For b-Lg the genotipic frequencies were 7,14% AA, 57,14% AB and 35,71% BB, and the gene frequencies were 64% for the allele A and 36% for the allele B. There was no trace of association between these two markers and the milk production for this herd

ASSUNTO(S)

leite produção teses bovino de leite melhoramento genético teses polimorfismo (genética) teses

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