Effect of breed, age and pasture periods on milk yield, milk components, somatic cell counts and lipid profiles of raw milk from Morkaraman and Tushin Sheeps
The aim of this study was to investigate the effects of breed, age of sheep, and pasture periods on the milk yield, milk components, somatic cell counts (SCC), and lipid profiles of forty-one Morkaraman and forty-seven Tushin sheep maintained in a traditional grazing system of natural pastures. Milk samples were collected for milk component, SCC, and lipid profiles analysis at the beginning of the pasture, mid-pasture, and the end of the pasture. Data were analyzed as repeated measurements by twoway ANOVA in the General Linear Model (GLM) procedure. The mathematical model included the effects of breed, pasture periods, ages, and all interactions. Bivariate correlations procedure was used to determine the relationship between milk components and lipid profiles. It was determined that breed was not significant for lactation traits. Milk yield, daily average milk yield (p<0.05), and lactation length (p<0.01) were significantly affected by the age of sheep. Solids non-fat (SNF), density, and protein were affected by breed. It has been determined that the milk of Tushin sheep has higher SNF, density, and protein values than milk obtained from Morkaraman sheep. The pasture periods are significant in milk composition. The SNF, density, protein, lactose, and ash increased with the passing of the season. The effect of breed, pasture period, and age on SCC was found to be insignificant. Except for cholesterol (COL), the milk lipid profiles such as triacylglycerol (TAG), free fatty acid (FFA), monoacylglycerol (MON), and phospholipid (PL) in studied breeds were similar. The pasture periods had a highly significant
effect on lipid profile. The interactions breed x age, breed x pasture period, and pasture period x age were not significant for milk components and lipid profiles except for breed x age interaction in the milk fat. Consequently, the pasture is more effective on the milk composition and lipid profiles rather than the breed and age of sheep.