Abstract

Milk somatic cell count (SCC), an indicator of udder health and milk hygiene, has not been implemented either in milk payment systems or in the current selection index of Italian buffalo so far. As a matter of fact, there is room to improve udder health through genetic and management strategies in this species. Repeated milk SCC test-day (TD) records on the same animal are useful to derive novel phenotypes on lactation basis by using somatic cell score (SCS) and thus to disclose buffaloes with udder issues to be monitored. In this study, sources of variation of SCC-derived traits in buffalo milk were investigated and their effect on milk yield and composition traits was estimated. Mean SCS (SCS₁₅₀), standard deviation of SCS (SCS_SD₁₅₀) and severity (SEV₁₅₀, ratio between the number of TD SCC >200,000 cells/mL and total number of TD available in the first 150 DIM) in the first 150 days in milk were calculated using TD data of 45,312 lactations from 35,623 buffaloes. Sources of variation of such traits were investigated through a linear model. Both SCS₁₅₀ and SEV₁₅₀ increased with parity, whereas SCS_SD₁₅₀ decreased (p < .001). Subsequently, the three traits were separately included in the model as explanatory variables to estimate their effect on milk yield and composition traits. Results showed that milk yield and lactose content were lower in animals with high and variable SCS in the first 150 days of lactation (p < .001). This study opens the debate on the development of an udder health index for the Italian buffalo.

• HIGHLIGHTS

• So far, somatic cell count has not been considered in payment systems of buffalo milk in Italy.

• There is need to improve mastitis resistance and udder health in dairy buffaloes.

• Traits derived from test-day records can be used for management and breeding purposes in buffaloes.

摘要

牛奶体细胞计数（SCC）是乳房健康和牛奶卫生的指标，到目前为止，尚未在牛奶支付系统或意大利水牛的当前选择指数中实施。实际上，通过该物种的遗传和管理策略，仍有改善乳房健康的空间。在同一只动物上重复的牛奶SCC测试日（TD）记录可用于通过泌乳利用体细胞评分（SCS）得出泌乳基础上的新表型，从而揭示具有待监测乳房问题的水牛。在这项研究中，调查了水牛乳中SCC衍生性状的变异来源，并评估了它们对牛奶产量和组成性状的影响。平均SCS（SCS ₁₅₀），SCS标准偏差（SCS_SD ₁₅₀）和严重性（SEV ₁₅₀，使用来自35,623头水牛的45,312次泌乳的TD数据，计算出牛奶中头150天TD SCC> 200,000细胞/ mL的数量与前150天DIM中可用TD总量之间的比率。通过线性模型研究了这些性状的变异来源。SCS ₁₅₀和SEV ₁₅₀均按奇偶校验增加，而SCS_SD ₁₅₀减小（p  <.001）。随后，将这三个性状分别作为模型的解释变量纳入模型，以估算它们对牛奶产量和组成性状的影响。结果表明，在泌乳前150天中，SCS较高和可变的动物的牛奶产量和乳糖含量较低（p <.001）。这项研究开启了关于开发意大利水牛乳房健康指数的辩论。

• 强调

• 到目前为止，意大利的水牛奶支付系统尚未考虑体细胞计数。

• 需要改善乳牛的乳腺炎抵抗力和乳房健康。

• 从测试日记录中得出的性状可用于水牛的管理和繁殖目的。