Effect of breed and nutrition on milk quality of sheep

Abstract

Listen

Translate article

Sheep breeding has a relevant economic and environmental role in the Alps, where cheese production is often obtained from local breeds. Recent studies have emphasized the role of fatty acid composition and CLA content of fat because of its considerable contribution to the final nutritional characteristics of cheese and to the quality of fat intake in the diet of consumers. Aim of the study was to evaluate the breed and nutrition effects on fatty acid composition and CLA content of milk fat during lactation of four Alpine sheep breeds (Frabosana, Delle Langhe, Savoiarda and Lacaune). At beginning of lactation, animals were stabled and fed hay and concentrate (pea and corn meal). From 60 to 90 days in milk, all the ewes of the four breeds grazed on the same valley pastures, and from middle to late lactation on the same alpine pastures. Feed samples of hay, concentrate and pasture grass were analysed for chemical composition and fatty acid composition. Milk samples were collected from 4 animals of each breed at different stage of lactation, and analysed for fatty acid composition of fat and CLA. Data were analysed with the “Statistica” package for Principal Components Analysis (PCA). Results showed that two main principal components (PC) explained more than 50% of cumulative variance. The first PC was positively correlated to SFA amount and negatively correlated to MUFA and PUFA of milk fat; the second PC was negatively correlated to the total CLA of milk fat. The analysis scattered the 4 different breeds during the stabled phase (beginning of lactation), showing that the breed has an influence on fatty acid composition of milk fat and CLA when animal are fed the same diet. From 60 days in milk to end of lactation, when sheep grazed on valley or alpine pastures, the differences in fatty acid composition and CLA were influenced only by the diet. Further studies are needed to better understand the interaction between nutrition and lactation stage on characteristics of fatty acid composition and CLA content.