State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China.
College of Animal Science and Technology, Northwest A&F University, Yangling, China.
Microbiol Spectr. 2021 Oct 31;9(2):e0010521. doi: 10.1128/Spectrum.00105-21. Epub 2021 Sep 8.
Subclinical mastitis (SCM) is one of the highly infectious diseases in dairy cows with the characteristics of high incidence and nonvisible clinical symptoms. The gastrointestinal microbiota is closely related to mastitis. Inulin is a prebiotic fiber with functions in improving intestinal microbial communities and enhancing the host's immunity. However, the impact of dietary inulin on the rumen inner environment remains unknown. The current study investigated whether inulin could relieve SCM by affecting the profiles of ruminal bacterial and metabolites in dairy cows. Inulin inclusion rates were 0, 100, 200, 300, and 400 g/day per cow, respectively. Inulin increased milk yield, milk protein, and lactose and reduced the somatic cell counts (SCC) in milk. In serum, the concentration of proinflammatory cytokines, such as interleukin-6 (IL-6), IL-8, tumor necrosis factor α (TNF-α), and malondialdehyde (MDA) were decreased, and IL-4 and superoxide dismutase (SOD) were increased. Meanwhile, inulin increased the concentration of propionate, butyrate, and lactic acid (LA), while it decreased NH-N in rumen. The propionate- and butyrate-producing bacteria (e.g., and ) and several beneficial commensal bacteria (e.g., and ) as well as metabolites related to energy and amino acid metabolism (e.g., melibiose and l-glutamate) were increased. However, several proinflammatory bacteria (e.g., , Streptococcus, and Escherichia) were decreased, accompanied by the downregulation of lipid proinflammatory metabolites, for example, ceramide(d18:0/15:0) [Cer(d18:0/15:0)] and 17-phenyl-18,19,20-trinor-prostaglandin E. In the current study, the above indicators showed the best response in the 300 g/day inulin group. Overall, dietary supplementation of inulin could alleviate inflammatory responses in cows with SCM through improving the rumen inner environment. The correlation between mastitis and the gastrointestinal microbiome in dairy cows has been demonstrated. Regulating the profile of rumen microorganisms may contribute to remission of subclinical mastitis (SCM). Supplementation of inulin in the diets of cows with SCM could increase the abundance of short-chain fatty acid (SCFA)-producing bacteria and beneficial commensal bacteria in rumen and meanwhile the levels of amino acids and energy metabolism. Conversely, the abundance of ruminal bacteria and metabolites with proinflammatory effects were decreased. Our study suggests that the improvement of the rumen internal environment by inulin supplementation could ameliorate inflammatory responses during SCM in dairy cows and thus improve lactation performance and milk quality. Our results provide a theoretical basis for regulation measures of SCM in dairy cows.
隐性乳房炎（SCM）是奶牛中一种高度传染性疾病，具有发病率高和无明显临床症状的特点。胃肠道微生物群与乳腺炎密切相关。菊粉是一种具有改善肠道微生物群落和增强宿主免疫力功能的益生元纤维。然而，日粮菊粉对瘤胃内环境的影响尚不清楚。本研究探讨了菊粉是否可以通过影响奶牛瘤胃细菌和代谢物的特征来缓解 SCM。菊粉的添加率分别为 0、100、200、300 和 400 g/天/头。菊粉增加了产奶量、乳蛋白和乳糖，降低了牛奶中的体细胞计数（SCC）。在血清中，促炎细胞因子（如白细胞介素-6（IL-6）、白细胞介素-8、肿瘤坏死因子-α（TNF-α）和丙二醛（MDA）的浓度降低，而白细胞介素-4 和超氧化物歧化酶（SOD）的浓度增加。同时，菊粉增加了丙酸、丁酸和乳酸（LA）的浓度，而降低了瘤胃中的 NH-N。丙酸和丁酸产生菌（如 和 ）和几种有益共生菌（如 和 ）以及与能量和氨基酸代谢相关的代谢物（如棉子糖和 L-谷氨酸）增加。然而，几种促炎细菌（如 、链球菌和大肠杆菌）减少，同时脂质促炎代谢物（如神经酰胺（d18:0/15:0）[Cer（d18:0/15:0）]和 17-苯基-18,19,20-三去甲前列腺素 E）的水平降低。在本研究中，300 g/天菊粉组的上述指标反应最好。总的来说，日粮添加菊粉可以通过改善瘤胃内环境来减轻 SCM 奶牛的炎症反应。已经证明奶牛乳腺炎与胃肠道微生物组之间存在相关性。调节瘤胃微生物的特征可能有助于缓解亚临床乳腺炎（SCM）。在 SCM 奶牛的日粮中补充菊粉可以增加瘤胃中短链脂肪酸（SCFA）产生菌和有益共生菌的丰度，同时增加氨基酸和能量代谢水平。相反，具有促炎作用的瘤胃细菌和代谢物的丰度降低。我们的研究表明，通过菊粉补充改善瘤胃内环境可以改善奶牛 SCM 期间的炎症反应，从而提高泌乳性能和牛奶质量。我们的结果为奶牛 SCM 的调控措施提供了理论依据。
