Bulk Milk Somatic Cell Count and Aerobic Plate Count on New Zealand Dairy Sheep Farms

Our objectives were to describe bulk milk somatic cell count (SCC) and aerobic plate count (APC), and their association, on New Zealand dairy sheep farms. We retrospectively collated data from 907 bulk milk SCC and APC consignments from 16 farms over the 2022–2023 season. Bulk milk SCC had a geometric mean of 659,491 cells/mL, with farm geometric means ranging from 358,198 to 1,278,382 cells/mL. APC exceeded 100,000 CFU/mL in 200/896 (22.3%) consignments, peaked in August, and the farm‐level proportion exceeding this threshold varied from 2.9% to 100%. The lowest quarter of farms for season mean log 10 SCC had a geometric mean SCC of 370,383 cells/mL, while the lowest quarter for the proportion of consignments exceeding 100,000 CFU/mL had 11/230 (4.8%) consignments above this threshold. A doubling in SCC was associated with approximately double the odds of APC exceeding 100,000 CFU/mL (OR = 2.09, 95% CI = 1.38–3.28), but high APC was not well predicted by SCC. We propose farm‐level aspirational targets of 400,000 cells/mL and less than 5% of consignments exceeding 100,000 CFU/mL for SCC and APC, respectively. Routine milk recording and careful attention to mastitis detection, milking hygiene, and plant maintenance may assist in achieving these targets.