The Influence of Season on the Cow Milk Quantity, Quality and Hygiene

Abstract

The purpose of this study was to evaluate the effects of season of collection on the quantity, quality and hygienicproperties of the raw milk delivered from one dairy farm. The studied traits were: bulk tank milk yield, chemicalcomposition (fat, protein, lactose, and total solids), freezing point, density, total bacteria count, coliform bacteriacount and somatic cell count, during years 2010 and 2011. A total of 727 samples were drawn and analysed in twolaboratories, using the standard methods. Average milk production per day per head in the farm was 13.58 kg,obtained from 252 cows. Year of collection had a significant effect on the bulk tank raw milk yield, quality andhygiene, except for freezing point and total bacteria count. The raw milk yield and chemical composition improved(p<0.05) from year 2010 to year 2011, as well as the hygienic quality. Season of collection had a significant (p<0.05)influence on the milk yield and chemical composition, the highest milk yield with the lowest concentration beingobtained during summer, while the lowest milk yield with the highest chemical composition was obtained in winter.Physical properties of the raw milk were less affected by the season of collection, with the lowest freezing point inthe winter and the highest density in the autumn. The highest somatic cell count and coliform bacteria count wasobtained during the spring and the lowest total bacteria count was obtained in winter season. There was a significant(p<0.05) interaction between year and season of production for all raw milk traits.