Dipartimento di Scienze Animali, Università degli Studi di Milano, via Celoria 2, 20133 Milano, Italy.
J Dairy Res. 2011 Nov;78(4):436-41. doi: 10.1017/S0022029911000598. Epub 2011 Aug 16.
The aim of the study was to investigate the effects of season, cow cleanliness and milking routine on bacterial and somatic cell counts of bulk tank milk. A total of 22 dairy farms in Lombardy (Italy) were visited three times in a year in different seasons. During each visit, samples of bulk tank milk were taken for bacterial and somatic cell counts; swabs from the teat surface of a group of cows were collected after teat cleaning and before milking. Cow cleanliness was assessed by scoring udder, flanks and legs of all milking cows using a 4-point scale system. Season affected cow cleanliness with a significantly higher percentage of non-clean (NC) cows during Cold compared with Mild season. Standard plate count (SPC), laboratory pasteurization count (LPC), coliform count (CC) and somatic cell count, expressed as linear score (LS), in milk significantly increased in Hot compared with Cold season. Coagulase-positive staphylococci on teat swabs showed higher counts in Cold season in comparison with the other ones. The effect of cow cleanliness was significant for SPC, psychrotrophic bacterial count (PBC), CC and Escherichia coli in bulk tank milk. Somatic cell count showed a relationship with udder hygiene score. Milking operation routine strongly affected bacterial counts and LS of bulk tank milk: farms that accomplished a comprehensive milking scheme including two or more operations among forestripping, pre-dipping and post-dipping had lower teat contamination and lower milk SPC, PBC, LPC, CC and LS than farms that did not carry out any operation.
本研究旨在调查季节、奶牛清洁度和挤奶程序对牛奶储罐中细菌和体细胞计数的影响。在一年中的不同季节，共对意大利伦巴第的 22 个奶牛场进行了三次访问。每次访问时，都从牛奶储罐中抽取样本进行细菌和体细胞计数；在奶牛挤奶前清洗乳房后，从奶牛乳房表面采集拭子样本。使用 4 分制系统对所有挤奶奶牛的乳房、侧腹和腿部进行评分，评估奶牛清洁度。与温和季节相比，寒冷季节奶牛的非清洁（NC）比例明显更高，表明季节会影响奶牛的清洁度。与寒冷季节相比，热季节牛奶中的标准平板计数（SPC）、实验室巴氏杀菌计数（LPC）、大肠菌群计数（CC）和体细胞计数（以线性评分 LS 表示）显著增加。与其他季节相比，冷季节拭子上凝固酶阳性葡萄球菌的计数更高。奶牛清洁度对牛奶储罐中的 SPC、嗜冷菌计数（PBC）、CC 和大肠杆菌有显著影响。体细胞计数与乳房卫生评分呈正相关。挤奶操作程序对牛奶储罐中的细菌计数和 LS 有强烈影响：完成包括除毛、预浸泡和后浸泡在内的两项或更多操作的农场，与未进行任何操作的农场相比，乳房污染程度更低，牛奶中的 SPC、PBC、LPC、CC 和 LS 也更低。
