Smistad Marit, Inglingstad Ragnhild Aab E, Skeie Siv
TINE SA, R&D Department, Farm Advisory Services, Chr. Magnus Falsens vei 18, 1432 Ås, Norway.
Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, N-1432 Ås, Norway.
JDS Commun. 2023 Nov 17;5(3):205-209. doi: 10.3168/jdsc.2023-0457. eCollection 2024 May.
Somatic cell count (SCC) is a widely used indicator of milk quality in the dairy industry. It is a relatively good indicator of udder health in dairy cows, but strongly confounded by non-infection factors, including season, in dairy goats. This study's objectives were to estimate the variation in SCC explained by season and stage of lactation. We also investigated associations between SCC and other milk quality parameters routinely measured, including total bacterial count, fat, protein, and lactose content, in different seasons and stages of lactation. In this observational study, we included results from the routine analyses of bulk milk samples (n = 5,180) collected every third day in 88 Norwegian goat herds through one year. Herd information was collected via a questionnaire and from the dairy herd recording system. The herds had a notable increase in bulk SCC associated with the pasture season. The median bulk SCC was 470,000 cells/mL in deliveries from the indoor spring period and 1,100,000 cells/mL in the pasture season. During the indoor fall season, when most goat herds are in late lactation, the median SCC was 940,000 cells/mL. The combined effect of the season and herd stage of lactation explained 53.5% of the variation in bulk milk SCC. Fat and protein contents varied significantly with season and stage of lactation, and the association with SCC was non-significant for fat content and explained less than 3% of the variation in protein content. Lactose content was associated with SCC, stage of lactation, and season. Total bacterial count was associated with SCC and the indoor seasons. Determination of normal seasonal variation of goat bulk milk SCC is necessary to establish thresholds for defining milk as abnormal and unacceptable for further processing and improving the usefulness of SCC as a tool for milk quality improvement in dairy goats. The results suggest that SCC thresholds for taking action to improve the milk quality should be adjusted for season and stage of lactation.
体细胞计数（SCC）是乳制品行业中广泛使用的牛奶质量指标。它是奶牛乳房健康状况的一个相对较好的指标，但在奶山羊中，它受到包括季节在内的非感染因素的强烈干扰。本研究的目的是估计季节和泌乳阶段对SCC变化的影响。我们还调查了在不同季节和泌乳阶段，SCC与其他常规测量的牛奶质量参数之间的关联，这些参数包括总细菌数、脂肪、蛋白质和乳糖含量。在这项观察性研究中，我们纳入了88个挪威奶山羊群一年中每隔三天采集的大量牛奶样本（n = 5180）的常规分析结果。通过问卷调查和奶牛群记录系统收集了畜群信息。与放牧季节相关，畜群的大量SCC显著增加。室内春季分娩时，大量SCC中位数为470,000个细胞/毫升，放牧季节为1,100,000个细胞/毫升。在室内秋季，大多数奶山羊群处于泌乳后期，SCC中位数为940,000个细胞/毫升。季节和泌乳畜群阶段的综合作用解释了大量牛奶SCC变化的53.5%。脂肪和蛋白质含量随季节和泌乳阶段有显著变化，脂肪含量与SCC的关联不显著，且对蛋白质含量变化的解释不到3%。乳糖含量与SCC、泌乳阶段和季节有关。总细菌数与SCC和室内季节有关。确定奶山羊大量牛奶SCC的正常季节性变化对于建立将牛奶定义为异常和不可用于进一步加工的阈值以及提高SCC作为改善奶山羊牛奶质量工具的实用性是必要的。结果表明应对改善牛奶质量采取行动的SCC阈值应根据季节和泌乳阶段进行调整。
