Patterns of milk production, blood metabolite profile and enzyme activities of two fat-tailed sheep breeds

This study was conducted to compare milk yield and composition, blood parameters and enzyme activities between two fat-tailed Iranian breeds of sheep (Mehraban and Sanjabi). Two groups of eight ewes per breed were kept indoors and fed a diet based on alfalfa hay (60%) and concentrates (40%). Milk production of the individual ewes was measured and sampled weekly for 11 weeks and blood samples were obtained at 28, 56 and 77 days of lactation. No significant differences between the breeds were evident in average daily milk production and fat and lactose contents, but average milk protein content tended to be higher (P = 0.05) in Mehraban than in Sanjabi ewes. However, milk and protein yields were higher (P < 0.05) in Mehraban ewes in the last two-thirds of lactation. Plasma lipid profile (triglyceride, cholesterol, HDL- and LDL-cholesterol) was not different between the two breeds at any time of study. At the end of lactation, plasma urea contents and alanine amino transferase activities were higher (P < 0.05) either before or after feeding in Mehraban than in Sanjabi ewes, which suggests a more intense metabolic activity in the former probably related to their higher milk and protein production at that stage of lactation.