Effects of Season on Ovine Milk Composition

Abstract

In the Mediterranean area, the seasonality of sheep milk production and quality heavily affects the dairy industry profitability. This research paper is aimed to study the changes of ovine milk composition in different months of the year. The composition of more than 126000 samples of bulk milk from grazing Sarda breed sheep, bred in Sardinia (Italy), collected in 2017 from January to July was studied. Milk main traits, physical-chemical parameters, and fatty acid composition were measured, and data analyzed by descriptive statistics, mean comparison test and multivariate statistical analysis. An increase of proteins and fat was observed in summer, accompanied by a decrease of proteins/fat ratio. Milk urea showed higher levels in winter-spring (January-April). Rumenic acid, trans-vaccenic acid and linolenic acid decreased in late spring-summer (May-July). Somatic cell levels were found not correlated with the bacterial count, and their trend suggests a dependence to milk dilution. NaCl content compensated the lower levels of lactose in the summer season. Based on a big data set, results highlighted the main differences in bulk milk composition, over a long period of the year. Differences can be attributed to traditional system of breeding.