摘要 : The effects of month of the year and breed of cattle on milk composition and cheese yield were investigated in 70 dairy herds (25 Holstein, 25 Swiss Brown and 20 Modicana) in Sicily, Italy, from September 1992 to July 1993. The se... 展开 The effects of month of the year and breed of cattle on milk composition and cheese yield were investigated in 70 dairy herds (25 Holstein, 25 Swiss Brown and 20 Modicana) in Sicily, Italy, from September 1992 to July 1993. The season of the year affected the percentage of total solids, milk fat, total and true protein, urea, casein as a percentage of true protein, and milk yield per day for all the breeds. The highest milk yield and the highest concentration of milk components were observed in December to May when the quantity and quality of green forage from native pastures was high. The Modicana cows had the highest contents of total solids, total protein, true protein, and non-protein nitrogen, and their milk fat content was similar to those of the Holstein and Swiss Brown. There was a tendency for higher casein as a percentage of true protein in milk from the Modicana cows. Electrophoretic analysis of the milk indicated that the Modicana cows in Sicily were of the kappa-BB genotype, while the Holstein and Brown Swiss were kappa-AA or kappa-AB. It was concluded that the milk from the Modicana cows had the highest potential for cheese yield. 收起