Effects of high-antioxidant activity Lactiplantibacillus plantarum inoculated alfalfa silage on rumen fermentation, antioxidant and immunity status, and mammary gland gene expression in dairy goats

Abstract Background During milk synthesis in lactating animals there is a high requirement for energy and oxygen which leads to an increase in the production of reactive oxygen metabolites (ROM), which causes an imbalance between oxidates and antioxidants concentration leading to oxidative stress (OS). In order to prevent OS and other metabolic disorders in dairy goats as well as provide a better understanding of diets’ effects on redox status during the lactation period, this feeding trial was conducted. The trial evaluated the effects of feeding inoculated alfalfa silage with Lactiplantibacillus plantarum strain containing high-antioxidant activity and its effects on rumen fermentation, immune status, and mammary gland gene expression in dairy goats. Methods Twenty-four Guanzhong dairy goats (38.1 ± 1.20 kg) were randomly allocated to two dietary treatments: one diet contain L. plantarum MTD/1 inoculated silage (RSMTD-1) and the other diet contain L. plantarum 24 − 7 with high antioxidant activity inoculated silage (ES24-7). Results Better fermentation quality and antioxidant activity were observed in ES24-7 than in the RSMTD-1 silage. Feed ES24-7 silage as a basal diet increased the total antioxidant capacity (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activities in milk, serum, and feces of the lactating goats. The diet with ES24-7 silage also improved casein yield, milk free fatty acid (FFA) content, and vitamin A content in the dairy goats’ milk. Meanwhile, an enhancement of immunoglobulin (Ig)A, IgG, IgM, interleukin (IL)-4, and IL-10 concentrations were observed, with a reduction in IL-1 β , IL-2, IL-6, interferon (IFN)- γ , and tumor necrosis factor (TNF)- α concentrations in the serum of the lactating goats fed ES24-7 dietary treatment. Higher concentrations of total volatile fatty acid (VFA), acetate, and propionate were determined in the rumen fluid of dairy goats fed ES24-7 silage. In addition, the diet of dairy goats containing ES24-7 silage significantly increased the expression of nuclear factor erythroid 2 like 2 ( NFE2L2 ), beta-carotene oxygenase 1 ( BCO1 ), SOD1 , SOD2 , SOD3 , GPX2 , CAT , glutathione-disulfide reductase ( GSR ), and heme oxygenase 1 ( HMOX1 ) genes of the mammary gland, and a reduction of NADPH oxidase 4 ( NOX4 ), TNF , and interferon gamma ( IFNG ) levels. Conclusions These findings indicated that feeding L. plantarum 24 − 7 inoculated alfalfa silage not only improved rumen fermentation and milk quality of lactating dairy goats, but also enhanced their immunity and antioxidant status by upregulating the levels of several antioxidant- and inflammatory-related genes of the mammary gland.