Journal Articles

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    Teat and udder morphology and pathology of New Zealand dairy ewes.
    (Taylor and Francis Group, 2025-02-12) Chambers G; Lawrence KE; Ridler AL; Laven RA
    AIMS: To describe the morphology and prevalence of teat and udder pathology of New Zealand dairy ewes. METHODS: 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. RESULTS: 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%. CONCLUSIONS: 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. CLINICAL RELEVANCE: 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.
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    Reduction in morbidity and mortality of dairy calves from an injectable trace mineral supplement
    (BMJ Group on behalf of the British Veterinary Association, 2019-06-01) Bates A; Wells M; Laven RA; Simpson M
    The effect of a multimineral preparation on the health and growth of spring born, dairy calves was investigated on four New Zealand pastoral farms. Calves were randomly allocated injections within 24 hours of birth, 35 days and 70 days after birth. Injections contained 40 mg zinc, 10 mg manganese, 5 mg selenium, 15 mg copper and 5 mg chromium per ml (Multimin+Se+ Cu+Cr Cattle, Virbac South Africa) at 1 ml/50 kg body weight. Morbidity, mortality from natural challenge and growth rates were recorded for 140 days. There were no differences in morbidity and mortality within 48 hours of birth for treated calves compared with controls, P=0.192. Morbidity and mortality were highest at 3-35 days (7.5 per cent [95 per cent CI 5.00 to 9.99] treated calves sick and 15.6 per cent [95 per cent CI 12.48 to 18.73] controls sick, P<0.001). For this period, mortality was lower at 4.4 per cent (95 per cent CI 2.49 to 6.41) treated calves and 10.4 per cent (95 per cent CI 7.78 to 13.03) controls, P<0.001. Allowing for potential confounders, the adjusted OR of treated calves scouring between 3 and 35 days was 0.44 (95 per cent CI 0.24 to 0.82, P=0.009). Allowing for potential confounders, from 0 to 140 days a second model predicted treatment approximately halved the probability of morbidity and mortality (P<0.001). There was no difference in the daily rate of gain (0.67 kg/day [95 per cent CI 0.66 to 0.67] for treated calves).