Efeitos dos marcadores genéticos da Beta-caseína na produção leiteira de vacas mestiças em Parintins, Amazonas

Abstract

The market for animal-derived products is under growing pressure to reinvent itself, driven by increasing consumer demand for options that promote health and well-being. The dairy sector is no exception, with A2A2 milk emerging as a notable response to this rising demand for functional products. Against this backdrop, the present study aimed to phenotypically assess the presence of the A2 variant of β-casein and its influence on milk production in cattle herds from the Parintins microregion, Amazonas. Milk samples were collected from thirteen crossbred cows belonging to a local dairy farm. Individual milk yield was monitored through production control, and samples were taken for further analysis. These samples were then sent to the Biotechnology Laboratory at ICSEZ/UFAM, where they were phenotyped using the Scienco Biotech® A2 Rapid Test to detect the presence of the A2 β-casein variant. Additionally, milk composition analyses were performed. Reproductive data were obtained from farm records of reproductive events. For statistical analysis, the SAS software (version 9.4) was used. Data were subjected to analysis of variance (ANOVA) with Tukey’s test at a 5% probability level, under a completely randomized design, comparing the A1A1 and A2A2 phenotypes with respect to milk composition (protein, fat, and lactose) and milk yield (MY). The results showed a predominance of the A2A2 phenotype (69.2%) compared with A1A1/A1A2 (30.8%) in the population studied. Regarding reproductive control, no records of reproductive events were found, which hindered the monitoring of key parameters and reflected reproductive efficiency indicators below expectations—potentially affecting the productive performance of the studied animals. Although statistical analysis did not reveal significant differences (p > 0.05) in protein and lactose levels between the A1A1 and A2A2 β-casein phenotypes, significant differences (p < 0.05) were observed for fat content and milk yield, with the A2A2 phenotype outperforming A1A1, as confirmed by Tukey’s test at a 5% probability level. These findings suggest a phenotypic influence on these productive traits; however, it is important to account for non-genetic factors, such as nutritional management, environmental conditions, and operational or structural constraints on the farm, which may also impact outcomes. It is worth noting that these data are preliminary and highlight the need for continued and more in-depth research. Nevertheless, the predominance of the A2A2 phenotype represents a key opportunity for genetic improvement programs aimed at boosting both productivity and milk quality in the region, thereby meeting the growing demand for healthier and more sustainable dairy products.