Multifactorial analysis of unstable non-acid milk occurrence in dairy production/ Análise multifatorial da ocorrência de leite instável não ácido em propriedades leiteiras

Abstract

The aim was to analyze the Unstable Non-Acid Milk (UNAM) phenomenon through the association of zootechnical characteristics of the farms relating them to their occurrence. The data collection was carried out in 12 dairy farms which received a technical visit to learn the production system: handling, feeding, mineralization and milking procedures. The milk samples were analyzed for fat, protein, lactose, solids not fat, standard plate count, somatic cell count, pH, titratable acidity and ethanol test stability. Milk data were submitted to analysis of variance; association between zootechnical characteristics and UNAM were determined by logistic regression; and multivariate analysis of principal components was carried out. The occurrence of UNAM was verified in 25% of the evaluated farms. In UNAM herds 27% to 33% of the cows were classified as UNAM. The animals with UNAM milk was different between farms classified as Stable or UNAM, being 12% and 30% of cows, respectively. The detection of UNAM was possible when in the herd there are at least 23% of the animals producing UNAM milk. The three principal components identified covered the main areas of influence on the occurrence of UNAM: Quality and interaction with part of the solids; Production and relationship with lactose; Nutrition and correlations with part of the components. The classification of milk in the expansion tank as UNAM can only be identified when more than 23% of the animals were in this condition. The multivariate analysis identified that the nutritional balance of each cow was determining factor for UNAM presence.