Incidência do leite instável não ácido em rebanhos leiteiros no sudoeste do Paraná

Abstract

The objective of this work was to identify the incidence and occurrence in different breeds and lactation periods of unstable milk without acidity (LINA), due to the great importance of the dairy chain in southwestern Paraná and milk quality. It was then sought, in two stages, to identify the incidence and differentiation of this in relation to normal milk. The first part of the study was the analysis of data provided by a dairy industry located in the center of the Southwest region of Paraná. There were 3,874 samples analyzed in the period from October 2014 to October 2016. Subsequently, in the period from March to August of 2017, the experiment was carried out on a farm whose herd is composed of two breeds: Dutch (60%) and Jersey (40%). The two groups, defined according to race, received the same diet and were kept in the same production system (grazing). The experimental design was a factorial, using the two races (Dutch and Jersey) and factor B as the three lactation stages (0 to 100, 101 to 200 and over 201 days in lactation). The results of both were submitted to the statistical analyzes using the statistical program GENES. For comparative analysis of the data, Tukey's test was used at 5% significance. It was verified that the period of greatest incidence of LINA in the Southwest of Paraná is the fall season. Dutch cows are more susceptible, regardless of the lactation stage when compared to Jersey cows subjected to the same management. The lactation period between 101 and 200 days in lactation presents higher percentage of LINA in the Dutch herd.