Udder health outcomes in Irish herds participating in CellCheck dry cow consults

The CellCheck dry cow consult (DCC) was developed by the CellCheck Technical Working Group to enable farmers to engage with their nominated veterinarian to develop farm-specific selective dry cow therapy (SDCT) plans, where appropriate. This study evaluated the effect of the DCC on farmer decision-making around dry cow therapy, and the udder health effects of implementing SDCT, in study herds over the 2019 and 2020 dry periods. The DCC was a 3-h consult, delivered and funded as part of the Targeted Advisory Service on Animal Health. Herds that completed a DCC were invited to register for a dry cow review the following year. The combined dataset for analysis across both years comprised 439 herds and 25,357 cows. Herd size ranged from 25 to 800. The median SCC of cows dried off with teat sealant only was 47,000 cells/mL before drying off in 2019 and 48,000 cells/mL at first milk recording in 2020, and 43,000 cells/ mL before drying off in 2020 and 39,000 cells/mL at first milking recording in 2021. Following both the 2019 and 2020 dry periods, cows tended to converge toward a similar median SCC early in the following lactation, irrespective of prior dry cow treatment strategy. The uptake of SDCT was greater in review herds, with 21% of cows receiving teat sealant only in 2020, compared with 16.3% of cows in herds participating in a consult for the first time in 2020. At an individual cow level, in both years dry period new infection rate (NIR) was approximately 2.7% higher for cows treated with teat sealant only, than for those treated with both dry cow antibiotic tubes and teat sealant, and 1.2% higher than cows treated with antibiotic only. Regardless of treatment, a significant association was detectable between increasing parity and the risk of a dry period new infection. Increasing herd size had a significant effect on the risk of dry period NIR. At a herd level, no significant increase in NIR occurred when SDCT was used compared with herds where blanket dry cow therapy was used. Though not without risk, SDCT can be successfully implemented in Irish herds; however, constant attention to hygiene and management is essential. Despite the challenges, facilitating continued farmer education and engagement with professional guidance will be important.