The research was performed to investigate effects of calving season and lactation order on milk yield components and changing of milk components with lactation stage in Simmental cows. Milk samples were taken at AM milkings in 30±15th, 90±15th, 150±15th and 210±15th days of lactations. Lactation stages' effect was found significant level statistically on only the rate of total solid matter (TSM). Calving season's effect was found at significant level statistically on 305-day milk yield; fat, protein, TSM, casein rates and lactation yield of casein. Although lactation order's effect was significant on all the component rates and yields of lactation except casein rate and SNF yield.

The research was performed to investigate effects of calving season and lactation order on milk yield components and changing of milk components with lactation stage in Simmental cows. Milk samples were taken at AM milkings in 30±15th, 90±15th, 150±15th and 210±15th days of lactations. Lactation stages' effect was found significant level statistically on only the rate of total solid matter (TSM). Calving season's effect was found at significant level statistically on 305-day milk yield; fat, protein, TSM, casein rates and lactation yield of casein. Although lactation order's effect was significant on all the component rates and yields of lactation except casein rate and SNF yield.