Qualidade do leite cru tipo B de quatro propriedades da região do Vale do Taquari, RS / Quality of raw grade B milk from four farms in the region of Vale do Taquari, RS, Brazil

ABSTRACT

Background: Milk is a complete food and an important source of essential nutrients. However, it can contain hazards which pose risks to the public health and their prevention depends on the adoption of good agricultural practices. Milk quality is associated with its normal physical-chemical and microbiological parameters. It depends on the nutrition, welfare and health of animals, as well as on the hygiene of the milking process, milk storage temperature, hygiene and temperature of the milk during transportation, product frauds, among other factors. This study aimed at assessing the quality of raw grade B milk produced in the town of Teutônia, RS, Brazil. Materials, Methods & Results: The infrastructure and milk quality of four farms were analyzed between January and April 2009, considering their proximity to the milk cooperative. Infrastructure data was obtained through questionnaires. Two milk samples were collected from expansion tanks and forwarded to milk laboratories in order to undergo antibiotic analysis, TRAM, determination of the freezing point, alcohol-alizarin test, determination of titratable acidity, density and fat contents. Additionally, an analysis of fraudulent substances in milk and the Whiteside test were performed in order to identify mastitis. Milk samples were forwarded once a month, during 4 months, to the Milk Cattle Analyses Service [Serviço de Análises de Rebanhos Leiteiros (SARLE), Universidade Federal de Passo Fundo (UPF), RS] in order to determine the somatic cell count (CCS) and total bacterial count (CBT). All milk samples had a good physical-chemical quality. The CCS and CBT were above the legal parameters in some samples and this fact was crucial to adapt the producers to the legislation in force. The farm showing the best results in the analyses was that with the best hygienic conditions, both in the facilities and in the milking process, evidencing that good management practices lead to better milk quality. Discussion: The farms showed unwanted CCS and CBT values in certain months because they did not adopt milking lines, an important management practice in mastitis prevention. Other factor that contributed to an increase in these counts was the teat washing practice, since water can be an important source of contamination if not treated properly. The pre-dipping practice is also a valuable mastitis prevention tool; however, farms 1 and 2 did not adopt this procedure or its execution was incorrect, which may have contributed to the high somatic cell count observed in all months of the study. Acid milk is a major problem encountered by dairy factories and it is important to perform acidity and alcohol-alizarin tests to detect errors in the preservation of milk. However, the farms in question showed satisfactory values for these analyses, since their milk was correctly preserved in direct expansion coolers. The density values indicate adequate quantities of fat and non fat milk solids for the producers studied, since they were in accordance with the legislation in force. In the Whiteside test, only farm 1 showed unsatisfactory results associated with a high CCS; however, the result of the remaining farms does not exclude the possibility of subclinical mastitis. All milk samples from farm 4 presented satisfactory CBT values, which is the consequence of an adequate hygienic management, a fact evidenced by the mastitis control procedures in use in the farm. The results varied in the remaining farms, indicating animal management irregularities.