Feruloyl esterase produced by certain microorganisms can help breakdown plant fiber. We investigated effects of inoculating feruloyl esterase-producing lactic acid bacteria (FLAB) in alfalfa silage on production performance and blood and liver markers of inflammation and oxidative stress in lactating dairy goats. Alfalfa was ensiled for 1 mo without additive (control, CON), with Limosilactobacillus reuteri YM13 without feruloyl esterase activity (YM13), or with a feruloyl esterase-producing L. reuteri A4-2 (A4-2). Forty-two dairy goats (53 ± 4 DIM; 37.2 ± 2.3 BW) were randomly assigned to 1 of 3 dietary treatments (n = 14/treatment) prepared with the above alfalfa silages and fed during 60 d. Silage and composite samples (concentrate + silage) were taken weekly. Jugular vein blood samples were taken on d 20, 40, and 60 before the morning feeding. Dairy goats were milked 2 × per day and milk samples taken on d 58 to 60. Five dairy goats from each group were slaughtered at the end of the experiment, and liver tissue samples collected for real-time quantitative PCR (RT-qPCR) assay. Serum antioxidant activity on d 20, 40, and 60, and production data were analyzed with PROC MIXED (SPSS 21.0, SPSS, Inc., Chicago, IL, United States). Biochemical indicators in silage and composite feed, and serum cytokine, immunoglobulin, biochemical indicators, and liver RT-qPCR in samples harvested on d 60 were analyzed using one-way ANOVA (SPSS 21.0, SPSS, Inc., Chicago, IL, United States). Compared with CON and YM13, inoculating with L. reuteri A4-2 led to lower silage pH and aNDF, but greater concentrations of lactic acid and ferulic acid along with activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), and total antioxidant capacity (T-AOC). Feeding A4-2 inoculated alfalfa silage did not alter dry matter intake, milk yield, or feed efficiency. Dairy goats fed A4-2 had greater serum total antioxidant activity, and lower pro-inflammatory cytokine concentrations at 60 d. Furthermore, greater total protein, albumin, and immunoglobulin M (IgM), and lower alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase in serum were also observed in response to feeding A4-2. Compared with CON and YM13, overall mRNA abundance of the nuclear factor-E2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway genes NFE2L2, HMOX1, NQO1, SOD2, CAT, GPX1, GPX2, and GSR was greater in the liver of goats fed A4-2. In contrast, relative to CON and YM13 groups, feeding A4-2 resulted in an overall downregulation of KEAP1 and the nuclear factor kappa-B (NF-κB) signaling pathway-related genes NFKB1, RELA, NOX4, TNF, and IFNG. Overall, feruloyl esterase-producing lactic acid bacteria used as silage inoculant can confer potential health benefits without affecting production performance. Further studies to determine the specific mechanisms controlling these responses are warranted.
Li et al. (Sun,) studied this question.