| Resumo: |
Production information of 29 milk producers in the southern region of Chile was studied with the objective of characterizing and classifying different dairy production systems, evaluating various associations between quantitative and qualitative studied variables and analyzing the effect of the production system and the quality of bovine milk according to the month of the year that it was processed. The classification of production groups was based on the implementation of the exploratory multivariate technique, main components analysis and conglomerates or cluster analysis. The applied statistical model was: y ijk = µ + Mi + SPj + MSPij + e ijk, where y ijk=dependent variables (fat, protein, count of somatic cells and colony forming units); µ=general average; M=effect of i-th month; SPj=effect of j-th productive system; MSPi j=month-productive system interaction; e ijk=random residual effect. The price per liter of milk paid to producer was discarded for the construction of groups, since they presented a low discriminatory power given a coefficient of less than 20 % variation. Different correlations between analyzed variables are discussed. Five production systems are described using the qualifying variables and original systems. In general, more intensive production systems presented lower values of fat (%) and protein (%), but showed greater superiority in the quality of sanitary milk than dairy farms with minor animal load. Regarding seasonality, as winter turns to spring, protein (%) associated with a decrease in the fat (%) increases, which determines an inverse relationship between both variables.
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