Relationship between somatic cell count and reproductive parameters in dairy cows

Milk yield, somatic cell count and reproductive performance are the main determinants of dairy enterprise profit, and udder health status is a factor that has a detrimental effect on both traits [1]. Rearte et al. [2] have reported the effect of somatic cells counts (SCC) on different indicators of reproductive performance, such as longer days to first service, lower conception risk and higher risk of pregnancy loss. The aim of this work was to analyze the influence of the count somatic cells in cow’s milk on reproduction in dairy cows. The study was carried out on 300 Holstein lactating dairy cows, in accordance with the Law on the Care, Keeping and Use of Animals of the Republic of Lithuania. According to the count of somatic cells in milk, cows were selected and divided into three groups: Group 1 – SCC up to 200 thousand/mL (N = 100); Group 2 – SCC 201–400 thousand/mL (N = 100); Group 3 – SCC > 401 thousand/mL (N = 100). Information on cow herd reproduction (service period in days, insemination index, duration of calving in days, first heat after calving in days) was taken from the herd management system. Arithmetic means, their errors and statistical reliability of the data were calculated for each evaluated trait. Statistically reliable data were considered when P < 0.05. The study demonstrated a significant relationship between somatic cell count in milk and reproductive performance in dairy cows. Higher SCC levels (> 401 thousand/mL) were associated with a 40.76% increase in the service period, a 1.9-fold increase in the insemination index (P < 0.05), and a two-day delay in the first oestrus after calving. Additionally, gestation duration slightly decreased by 0.82% compared with cows with SCC below 200 thousand/mL. These findings highlight the negative impact of elevated SCC on reproductive efficiency, emphasizing the importance of effective udder health management in dairy farming.