Abstract：
Total bacterial count (TBC) and SCC are important quality parameters in goat milk. Exceeding the bulk milk TBC (BMTBC) thresholds leads to price penalties for Dutch dairy goat farmers. Controlling these milk quality parameters can be challenging, especially around kidding. First, we describe the variation and the peaks around kidding of TBC and SCC in census data on Dutch bulk milk over the last 22 yr. Second, to explore causes of these elevations, we studied the variation of TBC and SCC in individual goat milk from 3 wk before to 5 wk after kidding and their association with systemic response markers IFN-γ, calprotectin, BHB, BCS, and fecal consistency. We visited 4 Dutch dairy goat farms weekly for 10 to 16 wk around kidding. Some of the goats had been dried off; other goats were milked continuously throughout pregnancy. A total of 1,886 milk samples from 141 goats were collected for automated flow cytometric quantification of TBC and SCC measurement. IFN-γ, calprotectin, and BHB were determined twice in blood of the same goats; most samples were collected after kidding. The BCS and fecal consistency were scored visually before and after kidding. We found a strong correlation between TBC and SCC (Spearman\'s rho = 0.87) around kidding. Furthermore, in the third week before kidding, the average TBC (5.67 log10 cfu/mL) and SCC (6.70 log10 cells/mL) were significantly higher compared with the fifth week after kidding, where the average TBC decreased to 4.20 log10 cfu/mL, and the average SCC decreased to 5.92 log10 cells/mL. In multivariable linear regression models, farm and stage of lactation were significantly associated with TBC and SCC, but none of the systemic response markers correlated with TBC or SCC. In conclusion, TBC and SCC in dairy goats were high in late lactation and decreased shortly after parturition. For SCC, the dilution effect might have caused the decrease, but this was not plausible for TBC. Moreover, the excretion of bacteria and cells in goat milk was not associated with the selected systemic response markers that were chosen as a readout for general immunity status, intestinal health, and metabolic diseases. Therefore, we assume that the TBC increase before kidding and the decrease after parturition are caused by other systemic, possibly hormonal, processes. To reduce BMTBC and bulk milk SCC, it would be advisable to keep milk of goats with highest numbers of bacteria and cells in their milk out of the bulk milk during end lactation. Further studies are needed to investigate the effects of withholding this end-lactation milk from the bulk tank.
摘要：
总细菌计数（TBC）和体细胞计数（SCC）是羊奶的重要质量参数。超过散装牛奶TBC（BMTBC）阈值会导致荷兰奶山羊养殖户的价格处罚。控制这些牛奶质量参数可能具有挑战性，尤其是在开玩笑。首先,我们描述了过去22年荷兰散装牛奶的人口普查数据中TBC和SCC的变化和峰值。第二,为了探索这些海拔的原因，我们研究了TBC和SCC在个别山羊奶中的变化，从3周前至5周后，他们与全身反应标志物干扰素-γ（IFN-γ）的关系，钙卫蛋白,β-羟基丁酸酯(BHB),身体状况评分（BCS）和粪便稠度。我们每周参观4个荷兰奶山羊养殖场，大约开玩笑10到16周。一些山羊已经干了，其他山羊在整个怀孕期间连续挤奶。从141只山羊中收集了总共1,886个牛奶样品，用于自动流式细胞术定量TBC和SCC测量。IFN-γ，在同一只山羊的血液中测定了两次钙卫蛋白和BHB，大多数样本都是在开玩笑后收集的。在开玩笑之前和之后对BCS和粪便稠度进行视觉评分。我们发现TBC和SCC之间存在很强的相关性（Spearman的rho=0.87）。此外，在开玩笑前的第三周，平均TBC（5.67log10cfu/mL）和SCC（6.70log10细胞/mL）明显高于开玩笑后第五周，其中平均TBC降至4.20log10cfu/mL，平均SCC降至5.92log10细胞/mL。在多变量线性回归模型中，农场和泌乳阶段与TBC和SCC显著相关，但没有一个全身反应标记与TBC或SCC相关。总之,奶山羊的TBC和SCC在泌乳后期较高，分娩后不久下降。对于SCC，稀释效应可能导致了减少，但这对TBC来说是不合理的。此外，羊奶中细菌和细胞的排泄与所选的全身反应标记无关，这些标记被选作一般免疫状态的读出，肠道健康和代谢疾病。因此,我们假设分娩前TBC的增加和分娩后的减少是由其他系统引起的，可能是荷尔蒙，进程。为了减少BMTBC和BMSCC，建议在哺乳结束时，将牛奶中细菌和细胞数量最多的山羊牛奶留在散装牛奶之外。需要进一步的研究来研究从散装罐中扣留这种最终泌乳奶的效果。
