Cattle milk quality in the Semiarid region of Rio Grande do Norte, Brazil

Resumo

The aim of this study was to evaluate the composition and quality of raw milk that was refrigerated in tanks, according to the farm structures, bovine diet, and production levels of the dairy producers that provide milk for the Association of Small-Scale Ranchers of the Angicos Wilderness (ASRAW). Data were collected from 47 dairy farmers from different cities of the state of Rio Grande do Norte who are associated with ASRAW. Twenty-three tanks were sampled throughout the month of June 2013, with two collections per week and five samples per tank, for a total of 920 samples. The properties were characterized according to the type of tank (private or community), the food provided during milk collection (voluminous or voluminous and concentrated), the structure of the dairy producer (family producer or non-family producer), and the amounts of each component. Analyses of fat content, total protein, casein levels, lactose levels, total solids, degreased dry extract (DDE), freezing point, urea levels, somatic cell counts (SCC), and antibiotic residues were performed. Statistical analyses were conducted for each group, and the means were compared by Tukey tests, with a critical significance level of 5% probability calculated with the PROC GLM procedure of the SAS® program. Most components differed significantly for each parameter. The highest difference was noted between the urea and SCC levels, which was probably due to the wide variety of dairy producer profiles. The SCC values exhibited the largest amplitude variations. Most milk components significantly differed according to the strata, producer, food, and tank. These changes probably had little influence on the animal’s physiology and productivity. Therefore, despite the small variations in the components of the milk supplied by ASRAW, the different types of milk storage tank, milk volume produced, and type of dairy producer affected the overall milk quality.