A Retrospective Study on the Risk Factors and the Effect of Higher Somatic Cell Count in Milk on Reproductive Performance in Dairy Cows

Abstract

This retrospective study evaluated the effect of somatic cell count (SCC) in milk during early lactation on reproductive performance in dairy cows. Data were collected on 774 cows from six dairy farms, including cow parity, dates of previous calving, artificial insemination, pregnancy diagnosis, incidence of postpartum endometritis, reproductive performance (the intervals from calving to first insemination and conception), milk production and SCC. Data on 774 lactations were grouped based on the average first 3 months postpartum linear somatic cell score (SCS) as T1 ( 0.05). The hazard of pregnancy by 365 DIM in the T3 group was lower (HR: 0.75, p < 0.05 respectively) than in the T1 and T2 groups. The SCS during 4 to 7 months postpartum differed (p < 0.0001) among the 3 groups. Farm and cow parity were important risk factors for higher SCS (≥ 4.0). Multiparous cows were more likely to have a higher SCS (OR: 2.26, p = 0.0005) compared with primiparous cows. In conclusion, higher SCS (≥ 4.0) during early lactation was associated with decreased reproductive performance of dairy cows.