Mastitis control in New Zealand dairy sheep: recommended benchmarks, practices, and research priorities from a baseline national research programme

Sheep milking in New Zealand has grown rapidly in the last 20 years. In the 2022-2023 season, a research project conducted on 20 commercial farms (estimated to represent approximately two-thirds of the New Zealand dairy sheep industry) established baseline parameters for udder health and milk quality. This paper synthesises findings from that project alongside relevant international dairy sheep mastitis literature to clarify what is known, what is uncertain, and what actions are most likely to accelerate progress in New Zealand. It proposes immediate, short-term, and medium-term priorities for mastitis control in New Zealand dairy sheep. We set benchmarks for clinical mastitis incidence (< 1.5%), subclinical mastitis prevalence (< 2%), and bulk-milk aerobic plate count (< 5% consignments ≥ 100,000 cfu/mL) and somatic cell count (season mean < 400,000 cells/mL) using the mean of the best 25% of farms. On-farm practices most likely to achieve these benchmarks are summarised, including milk recording, use of the rapid mastitis test, somatic cell count thresholds, milking hygiene methods, and udder conformation scoring. Research priorities include determining the factors associated with high bulk-milk aerobic plate count, clarifying mastitis identification and management when multiple milk-recording events take place within a season, extending the preliminary investigation of mastitis risk factors and treatments, confirming the value of milking hygiene practices, and developing a rapid udder-conformation scoring system.