Quality of raw milk and management practices on dairy farms

Abstract

The overall objective of the study is to assess the risk factors associated with management practices and microbiological quality of milk, as well as to estimate the relative contribution of subclinical mastitis pathogens on the microbiological quality of raw milk on dairy farms. Additionally, the objective is to access the level of knowledge and opinions of dairy farmers about mastitis and milk quality. For this, a serie of three experiments are proposed to be developed over 3 years. For experiment 1, samples will be collected fortnightly in bulk milk of herds selected for a period of 6 months, totaling 600 samples, which will be subject to the following microbiological analysis: total bacterial count (TBC), preliminary incubation count (PIC), count of pasteurized milk (LPC) and coliform count (CC). To evaluate the risk factors associated with the microbiological quality of milk, two groups of herds will be formed (high and low microbiological quality) based on the results of the last six tests (three months) microbiological testing. The collection of information on dairy herds will be performed by a visit to answer a questionnaire on the following areas: general management of the farm, b) milking management, c) cleaning of milking equipment and utensils; d) cleaning conditions of the cow. For experiment 2, samples will be collected fortnightly in bulk milk of herds selected for a period of 6 months, totaling 300 samples, which will undergo somatic cell count and the following microbiological analysis: TBC, count Staphylococcus aureus, Streptococcus agalactiae count, coagulase-negative staphylococci, environmental streptococci counts, and enumeration of Escherichia coli. To assess the relative contribution of the causative agents of subclinical mastitis on the microbiological quality of milk, herds will be distributed in 3 classes for CCS tank based on the results of the last 6 tests (3 months). For experiment 3, it will be held, with each producer selected, structured interviews based on a questionnaire previously made. These interviews will be held by the responsible for the dairy or in his absence, with responsibility for the milking management. The questions will be divided into the following topics: i) socio-economic issues (the producers aim to stratify with respect to their income, output and other factors), ii) the level of knowledge regarding somatic cells, bacterial counts and mastitis (control, prevention and treatment), iii) producers' attitudes toward prevention practices of mastitis, milking hygiene and equipment, refrigeration of milk. (AU)