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首页> 外文期刊>Livestock Science >Time-to-event analysis of mastitis at first-lactation in Valle del Belice ewes.
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Time-to-event analysis of mastitis at first-lactation in Valle del Belice ewes.

机译：Valle del Belice母羊初次泌乳期间乳腺炎的事件分析。

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A time-to-event study for mastitis at first-lactation in Valle del Belice ewes was conducted, using survival analysis with an animal model. The goals were to evaluate the effect of lambing season and level of milk production on the time from lambing to the day when a ewe experienced a test-day with a recorded SCC greater than or equal to 750,000 cells/ml, and to estimate, for this trait, its heritability and the percentage of variation explained by the flock-year of lambing effect. A dataset with 2468 first-lactation records, collected from 1998 to 2003 in Valle del Belice ewes allocated in 17 flocks, was used. The Cox model used included lambing season and total milk yield adjusted for lactation length as fixed effects and flock-year of lambing effect and individual additive genetic effect as random effects. In total 40.5% of the records were censored. Results indicated that ewes lambing from April to July were at a higher risk of mastitis than those lambing from August to November (conventional season), and that ewes in the highest class of milk production were at a higher risk of mastitis than those in the lowest level. The heritability for the time interval between lambing and first test-day with mastitis was 3% on the logarithmic scale and 4% on the real scale. The proportion of variation, in the time interval between lambing and first test-day with mastitis, explained by the flock-year of lambing effect was 19% on the logarithmic scale and 27% on the real scale; this seems to stress the importance of flock management..
机译：使用动物模型的生存分析，对Valle del Belice母羊初乳中的乳腺炎进行了一项事件调查研究。目的是评估产羔季节和产奶量对从产羔到母羊经历测试日（记录的SCC大于或等于750,000个细胞/毫升）的时间的影响，并估计羊群效应的羊群年解释了这种性状，遗传力和变异百分率。使用了1998年至2003年间在Valle del Belice母羊中分配的17468头母羊的初乳记录2468个数据集。使用的Cox模型包括产羔季节和根据泌乳期调整的总产奶量作为固定效应，羊群效应的羊群年和个体累加遗传效应作为随机效应。总共检查了40.5％的记录。结果表明，从4月至7月产羔的母羊患乳腺炎的风险要比从8月至11月（常规季节）产的母羊的乳腺炎高。水平。在产羔和乳腺炎第一个测试日之间的时间间隔的遗传力以对数标度为3％，以实际标度为4％。在产羔和乳腺炎第一个测试日之间的时间间隔中，变异的比例由成年产羔效应解释，对数标度为19％，实际标度为27％;这似乎在强调羊群管理的重要性。

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