The effect of somatic cell count on milk yield and milk composition on day seven postpartum in cows

The aim of this study was to evaluate the effects of somatic cell count (SCC) on the milk yield and milk composition (nonfat solid, fat, protein, lactose, casein) on day 7 postpartum in Holstein cows. Milk samples (n=794) were assessed with consideration of parity (primiparous and multiparous) and seasonal effect (spring, summer, fall, winter). The SCCs of the milk samples were divided into three groups as follows: G1: 105 cells/mL; G2:105 - 4??105 cells/mL; and G3: 4??105 cells/mL. The mean log10 SCC was 5.19 cells/mL on day 7 postpartum. The SCC values were transformed into log10 SCC. The mean log10 SCC was determined as 4.72 cells/mL for G1, 5.31 cells/mL for G2, and 5.77 cells/mL for G3. The lowest log10 SCC was determined in winter, while the highest milk yield was determined in the spring. While the nonfat solid, fat, protein, and casein were higher in primiparous cows, the log10 SCC numerically increased (5.17 vs. 5.24 cells/mL, respectively) with the higher milk yield of multiparous cows. The nonfat solid, fat, protein, lactose, casein, and milk yield were 9.14%, 3.63%, 3.66%, 5.01%, 2.69% and 33.49kg/day for G1, respectively. A reduction in milk components was evident when the SCC exceeded the healthy udder threshold (>100,000 cells/mL). The critical threshold for SCC can be determined as 100,000 cells/mL for evaluation of the milk component loss in the early postpartum period. In addition, determination of increased somatic cell count by individual measurements as early as possible after parturition can prevent the exacerbation of milk composition loss throughout lactation in cows.