Association of High Somatic Cell Counts Prior to Dry off to the Incidence of Periparturient Diseases in Holstein Dairy Cows

SIMPLE SUMMARY: In this study, we looked at a possible link between udder infection in dairy cows one week before drying off and the incidence of several periparturient diseases postpartum, including uterine infection (metritis), lameness, ketosis, and retained placenta. Infection of the mammary gland in dairy cows is associated with a strong host immune response and the transfer of neutrophils known as somatic cells. If the number of somatic cells in the milk is greater than 200,000 cells/mL of milk, the cow has subclinical or clinical mastitis; if the number of SCC is less than 200,000 cells, the cow is considered healthy. According to the findings of this study, cows with a high somatic cell count in their milk before drying off had a higher incidence of ketosis postpartum. Cows with a high somatic cell count were more likely to have a retained placenta, uterine infection, and lameness after calving. Infection of the udder, as indicated by high somatic cell counts in the milk, was also linked to lower milk yield and lower concentrations of milk sugar and protein. Our findings suggest that udder inflammation prior to drying off can make dairy cows more susceptible to other periparturient diseases. ABSTRACT: Intramammary infections (mastitis) of dairy cows, along with other periparturient diseases, have become problematic within the dairy industry as they lead to loss of milk production. The main objective of this study was to determine whether elevated somatic cell counts (SCC) in cows prior to drying off are related to the incidence of other periparturient diseases. Additionally, we determined whether milk composition and milk yield are affected by a high SCC prior to drying off. Somatic cell counts of milk samples were determined prior to dry off (n = 140) and were used to classify cows in the study as high (>200,000 cells/mL) or low (<200,000 cells/mL) SCC. The composition of milk was analyzed before drying off and at 1 and 2 weeks after calving. The results showed that an elevated SCC before drying off was related to the incidence of ketosis. Cows with a high SCC at drying off also showed an increased likelihood of retained placenta, metritis, and lameness postpartum; however, it was not statistically significant. Milk lactose was lower in cows with high SCC, whereas protein content was lower after parturition. Milk production was lower for cows with pre-drying elevated SCC, particularly for cows with retained placenta, ketosis, and mastitis. In conclusion, cows with pre-drying elevated SCC were more likely to develop disease after parturition and produce less milk and with lower lactose and protein content.