Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padova, IT-35020, Legnaro (PD), Italy.
Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padova, IT-35020, Legnaro (PD), Italy.
J Dairy Sci. 2024 Jan;107(1):593-606. doi: 10.3168/jds.2023-23729. Epub 2023 Sep 9.
Udder health has a crucial role in sustainable milk production, and various reports have pointed out that changes in udder condition seem to affect milk mineral content. The somatic cell count (SCC) is the most recognized indicator for the determination of udder health status. Recently, a new parameter, the differential somatic cell count (DSCC), has been proposed for a more detailed evaluation of intramammary infection patterns. Specifically, the DSCC is the combined proportions of polymorphonuclear neutrophils and lymphocytes (PMN-LYM) on the total SCC, with macrophages (MAC) representing the remainder proportion. In this study, we evaluated the association between DSCC in combination with SCC on a detailed milk mineral profile in 1,013 Holstein-Friesian cows reared in 5 herds. An inductively coupled plasma-optical emission spectrometry was used to quantify 32 milk mineral elements. Two different linear mixed models were fitted to explore the associations between the milk mineral elements and first, the DSCC combined with SCC, and second, DSCC expressed as the PMN-LYM and MAC counts, obtained by multiplying the proportion of PMN-LYM and MAC by SCC. We observed a significant positive association between SCC and milk Na, S, and Fe levels. Differential somatic cell count showed an opposite behavior to the one displayed by SCC, with a negative association with Na and positive association with K milk concentrations. When considering DSCC as count, Na and K showed contrasting behavior when associated with PMN-LYM or MAC counts, with decreasing of Na content and increasing K when associated with increasing PMN-LYM counts, and increasing Na and decreasing K when associated with increasing MAC count. These findings confirmed that an increase in SCC is associated with altered milk Na and K amounts. Moreover, MAC count seemed to mirror SCC patterns, with the worsening of inflammation. Differently, PMN-LYM count exhibited patterns of associations with milk Na and K contents attributable more to LYM than PMN, given the nonpathological condition of the majority of the investigated population. An interesting association was observed for milk S content, which increased with increasing of inflammatory conditions (i.e., increased SCC and MAC count) probably attributable to its relationship with milk proteins, especially whey proteins. Moreover, milk Fe content showed positive associations with the PMN-LYM population, highlighting its role in immune regulation during inflammation. Further studies including individuals with clinical condition are needed to achieve a comprehensive view of milk mineral behavior during udder health impairment.
乳房健康对可持续牛奶生产至关重要，各种报告指出，乳房状况的变化似乎会影响牛奶的矿物质含量。体细胞计数（SCC）是用于确定乳房健康状况的最公认指标。最近，提出了一个新的参数，即差异体细胞计数（DSCC），用于更详细地评估乳腺内感染模式。具体来说，DSCC 是总 SCC 中多形核粒细胞和淋巴细胞（PMN-LYM）的组合比例，巨噬细胞（MAC）代表其余比例。在这项研究中，我们评估了 DSCC 与在 5 个牛群中饲养的 1013 头荷斯坦-弗里生奶牛的详细牛奶矿物质谱之间的关联。使用电感耦合等离子体-光学发射光谱法来定量 32 种牛奶矿物质元素。拟合了两个不同的线性混合模型，以探索牛奶矿物质元素与以下两个方面的关联：第一，DSCC 与 SCC 的结合，第二，DSCC 表示为通过 SCC 乘以PMN-LYM 和 MAC 比例获得的PMN-LYM 和 MAC 计数。我们观察到 SCC 与牛奶中 Na、S 和 Fe 水平呈显著正相关。差异体细胞计数与 SCC 表现出相反的行为，与 Na 呈负相关，与 K 呈正相关。当考虑 DSCC 作为计数时，PMN-LYM 或 MAC 计数与 Na 和 K 呈相反的行为，PMN-LYM 计数增加时，Na 含量降低，K 含量增加，而 MAC 计数增加时，Na 含量增加，K 含量降低。这些发现证实 SCC 的增加与牛奶中 Na 和 K 含量的改变有关。此外，MAC 计数似乎反映了 SCC 模式，随着炎症的恶化而增加。PMN-LYM 计数则表现出与牛奶中 Na 和 K 含量相关的模式，这归因于调查人群中的大多数处于非病理性状态，PMN 比 LYM 更多。有趣的是，观察到牛奶 S 含量与炎症状况（即 SCC 和 MAC 计数增加）之间存在关联，这可能归因于其与牛奶蛋白（尤其是乳清蛋白）的关系。此外，牛奶 Fe 含量与PMN-LYM 群体呈正相关，这突出了其在炎症期间对免疫调节的作用。需要进行包括临床个体在内的进一步研究，以全面了解乳房健康受损期间牛奶矿物质的行为。
