Frequências Alélicas e Genotípicas do gene CSN-2(Beta Caseina) em gado leiteiro e perfil de conhecimento de consumidores de leite no Tocantins

Abstract

Currently, the dairy industry diversifies products with organoleptic, dietary, functional and nutritional properties based on consumer demands and customer well-being. Likewise, in production systems there is a concern about the quality and diseases that are related to the consumption of milk. Thus, the present study aimed to verify the allelic and genotypic frequencies of the CSN-2 gene (beta casein) in dairy herds in Tocantins, as well as the profile and level of knowledge of milk consumers in that state. Genetic material from 421 animals (crossbred dairy cattle in production) from three herds in the northern region of Tocantins were used, and a qualitative research, through a questionnaire, with 389 people distributed in 34 municipalities in the state, including data on milk consumption, knowledge and familiarity with A2 milk. Samples for two markers of the polymorphic regions were characterized and confirmed by real-time PCR using an ABI Prism® 7500 sequence detection system (Applied Biosystems). Allele 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. In relation to the consumer profile, a semi-structured questionnaire was carried out consisting of 19 questions, divided into three parts, the first with reference to the profile of the interviewee, the second aimed at identifying the consumption of dairy products in general, as well as the frequency and quantity consumed, while in the third there were questions regarding knowledge about A2A2 milk. The frequency of the A1 allele was 28.27%, and of the A2 allele, 71.73% in the sampled herd. The genotypic frequency of A2A2 was 52.96% (223/421), with A1A2 genotype of 37.53% (158/421), and 9.50% (40/421) of animals with A1A1 genotype. The frequency of the A1 allele for beta-casein in dairy herds in the northern region of Tocantins was low and followed the same trend already observed in the literature. The A2A2 beta-casein genotypes showed a high relative frequency, however the A1A2 genotype is still quite frequent, requiring greater selection pressure. Regarding the consumption of dairy products, 21.31% have some type of discomfort when consuming, and 46.27% have a weekly consumption of one to two liters, 28.28% between two to four liters and 25.45% with consumption of more than four liters, with milk being the main dairy product consumed by 59.13% of respondents. Of the 76.10% interviewed, they pay little or no attention to the label information, against 28.53%. About A2 milk, 40.36% against 59.64% had or did not have some knowledge. It was observed that 42.93% and 30.59% would be willing to pay more than 10% or more than 50%, respectively, and 24.94% revealed that they did not pay any increase over the value for A2 milk. A portion of the population has a level of demand regarding the quality and specificity of milk in relation to health problems. However, the ability to consume is directly linked to the level of knowledge and familiarity with A2 milk, as well as paying a low additional amount was related to consumers who heard about it, but who know little about this product and paying higher additional amounts was related to respondents who have heard about and know about the product.