ALLELIC AND GENOTYPIC FREQUENCIES OF THE CSN-2 GENE IN A POPULATION OF DAIRY CATTLE IN THE NORTHERN REGION OF THE STATE OF TOCANTINS

Resumo

The present study aimed to verify allelic and genotypic frequencies of the β-casein genes in a population of dairy cattle in the north of the state of Tocantins in order to identify animals capable of producing β-casein A2 in preference to its counterpart. To this end, five herds belonging to the cities of Araguaína, Arapoema, Araguatins, Colinas do Tocantins, and Palmas were selected, totaling 1,109 dairy cattle of mixed and/or Gir dairy breed. Samples for two markers of polymorphic regions were characterized and confirmed by real-time PCR, using an ABI Prism® 7500 sequence detection system (Applied Biosystems). Allelic and genotypic frequencies were determined using the TaqMan ™ detection system, in which the primer and probe emit different fluorescence signals for each allele of the polymorphism. The observed frequencies indicated a prevalence of the A2 allele (72.59%) compared to the A1 allele (27.41%). Considering the genotypic constitution of the animals, there was a greater correspondence for A2A2 (54.55%) compared to A1A1 (9.38%) and A1A2 (36.06%). This denotes a promising future for the development of economic activities focused on the production of type-A2 milk in the northern region of the state of Tocantins.

Keywords: Beta casein A1. Beta casein A2. Bovine milk. Hypersensitivity.