Mastitis is the most common disease affecting dairy goats and causing economic losses. Although it is accepted that increased somatic cell count (SCC) is mainly a response to infection, its reliability for subclinical mastitis detection in goats is controversial. Indeed, many physiological and extrinsic variables can increase SCC, including breed, parity, age, stage of lactation, seasonal variations, and milking methods. In some animals, milk-secreting tissue is present in the wall of the teat and, in some instances, milk can filter through pores in the skin to the udder surface. This condition is known as “weeping teat” (WT). In these animals, mammary tissue might be prone to develop bacterial infections, although limited information is provided. WT seems to have a genetic background and is reported to be especially found in goat breeds selected for high milk production. Moreover, it is observed a genetic correlation between WT and decreased milk yield as well as increased somatic cell scores (SCS). Since information on this topic is very limited, this study aimed at investigating any possible relationship between WT, high SCC and the presence of bacteria in goat milk. Alpine goat farms in Northern Italy were selected based on the presence of WT. Each herd was divided into two age-matched groups, identified as case (WT+) and control (WT-). Half-udder milk samples were collected aseptically at three timepoints; bacteriological analysis was performed, and SCC were determined and transformed in somatic cell score (SCS). There was a positive association between SCS and the presence of bacteria in milk (P = 0.037) overall, whereas WT udder defect was associated with positive bacterial culture in just one herd (P= 0.053). Thus, this herd was further investigated, repeating the sampling and the analysis on the following year. The positive association between high SCS and the presence of bacteria in milk was then confirmed (P = 0.007), whereas no association with WT condition was found. These results indicate that WT defect is usually unrelated to both the outcome of milk bacterial culture and SCS. As a side outcome, we could confirme the role of bacterial infection in increasing SCS.

中文翻译：

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滴乳头对奶山羊乳房内感染及体细胞评分的影响

乳腺炎是影响奶山羊并造成经济损失的最常见疾病。虽然体细胞计数 (SCC) 增加主要是对感染的反应，但其在山羊亚临床乳腺炎检测中的可靠性仍存在争议。事实上，许多生理和外在变量都会增加 SCC，包括品种、胎次、年龄、泌乳阶段、季节变化和挤奶方法。在某些动物中，乳头壁中存在分泌乳汁的组织，在某些情况下，乳汁可以通过皮肤上的毛孔过滤到乳房表面。这种情况被称为“哭泣的乳头”（WT）。在这些动物中，尽管提供的信息有限，但乳腺组织可能容易发生细菌感染。WT 似乎有遗传背景，据报道特别是在为高产奶量选择的山羊品种中发现。此外，观察到 WT 与牛奶产量降低以及体细胞评分 (SCS) 增加之间存在遗传相关性。由于有关该主题的信息非常有限，因此本研究旨在调查 WT、高 SCC 和羊奶中细菌存在之间的任何可能关系。根据 WT 的存在，选择了意大利北部的高山山羊养殖场。每个牛群被分成两个年龄匹配的组，确定为病例（WT+）和对照（WT-）。在三个时间点无菌收集半乳样品；进行细菌学分析，测定SCC并转化为体细胞评分（SCS）。总体而言，SCS 与牛奶中细菌的存在呈正相关（P = 0.037），而 WT 乳房缺陷仅与一个牛群的阳性细菌培养相关（P = 0.053）。因此，对该猪群进行了进一步调查，并在第二年重复取样和分析。然后证实了高 SCS 与牛奶中细菌存在之间的正相关性（P = 0.007），而未发现与 WT 条件相关。这些结果表明 WT 缺陷通常与牛奶细菌培养和 SCS 的结果无关。作为一个附带结果，我们可以确认细菌感染在增加 SCS 中的作用。次年重复抽样和分析。然后证实了高 SCS 与牛奶中细菌存在之间的正相关性（P = 0.007），而未发现与 WT 条件相关。这些结果表明 WT 缺陷通常与牛奶细菌培养和 SCS 的结果无关。作为一个附带结果，我们可以确认细菌感染在增加 SCS 中的作用。次年重复抽样和分析。然后证实了高 SCS 与牛奶中细菌存在之间的正相关性（P = 0.007），而未发现与 WT 条件相关。这些结果表明 WT 缺陷通常与牛奶细菌培养和 SCS 的结果无关。作为一个附带结果，我们可以确认细菌感染在增加 SCS 中的作用。