Differential somatic cell count as an additional indicator for intramammary infections in dairy cows

摘要

Mastitis, often caused by intramammary infection(IMI), is a significant problem in dairy farmingglobally. Somatic cell count (SCC) is widely used asa parameter for screening IMI in cows that are thentreated or culled. We investigated the potential of anew parameter, differential SCC (DSCC), to detect IMIat cow level when SCC is already known. We achievedthis using bacterial culture (BC) and PCR to detect 4categories of pathogens (major, minor, other, and any)in 2 Danish dairy herds. Quarter milk samples werecollected from monthly dairy herd improvement samplingsover 1 yr and analyzed with BC, whereas cowleveldairy herd improvement samples were analyzedusing PCR. Days in milk, parity, and IMI status hada significant effect on DSCC. Using DSCC in additionto SCC significantly improved the indication of IMIcompared with using only SCC in the any pathogencategory in both herds as well as the minor pathogenscategory in herd 2 when BC was used for detection.When PCR was used to detect IMI, the use of DSCC inaddition to SCC was significant for the other pathogenscategory in herd 1 and the minor pathogens categoryin herd 2. Thus, our data revealed that DSCC can addsignificant information describing IMI status even whenSCC is already known; however, this depends on thecausative pathogen. Future studies may address howto use DSCC in practice as well as consider the availabilityof temporal data to potentially gain insight intothe course of infection.