Teat and udder morphology and pathology of New Zealand dairy ewes

To describe the morphology and prevalence of teat and udder pathology of New Zealand dairy ewes.

A repeated cross-sectional study was conducted on 20 commercial New Zealand dairy sheep farms over the 2022-2023 season. Approximately 15 randomly selected ewes were examined on each farm in early, mid, and late lactation. Four udder morphology measures were scored on a 5-point scale: depth (1 = pendulous, 5 = compact udder), suspension (ratio of width at abdominal attachment to height, 1 = low, 5 = high), gland separation (1 = zero, 5 = maximum separation), and teat placement (1 = distally located, vertically oriented, 5 = laterally located, horizontally oriented teats). Teat length and width were measured, and the presence of supernumerary teats, asymmetry, visible teat/udder inflammation, and lesions were recorded. Teats and glands were palpated for consistency, gland-nodules, teat canal thickening, and patency, and teat ends scored for hyperkeratosis. Teat and gland-level pathological variables were converted to ewe-level scores. The presence of involuted, non- or minimally lactating glands was recorded. Data were analysed using descriptive statistics.

Across the three visits, 893 observations were made on 882 unique ewes. Mean teat length and width were 27.5 (95% CI = 27.2-27.7) and 15.8 (95% CI = 15.7-15.9) mm. Udder depth, separation, suspension, and teat placement had modal scores of 4, 3, 3, and 3 respectively, and varied across visits and age groups. Asymmetrical udder prevalence was 39% (95% CI = 35.5-42%) overall and increased with age (27% for 1-year-olds, 38% for two-year-olds, 43% for mixed age ewes). Supernumerary teats were observed in 15% (95% CI = 13-17.9%) of ewes. There was between-farm variation in all udder morphology variables. Ewe-level prevalences of teat end hyperkeratosis (any degree of severity), gland/teat inflammation, lesions, palpable defects, and involuted glands were all < 6%.

Morphological observations resembled those from overseas dairy sheep. Teat dimensions, udder depth, separation, suspension, teat placement, and presence of supernumerary teats varied between farms. Udder depth, separation, and suspension scores decreased with age, while teat placement score and the prevalence of asymmetry increased with age. Teat and udder pathology were rare.

This is the first systematic study of teat and udder morphology and pathology in New Zealand dairy ewes. The data will be useful for farmers and industry partners, providing a comparison with their own flocks, identifying areas for improvement, and informing and contrasting with future studies.