Metabolomic and morphologic surveillance reveals the impact of lactic acid-treated barley on in vitro ruminal fermentation.

Objective: Lactic acid (LA) treatment of cereals is known to improve ruminant performance. However, changes in cereal nutrient levels and variations in rumen fermentation remain unclear. Method: This study was designed to compare the effects of 5% LA treatment on the trophic and morphological characteristics of barley and to discover the differences in rumen fermentation characteristics and metabolomes between LA-treated and untreated barley. Results: Compared with those of untreated barley (BA), the dry matter (DM), crude protein (CP), ash and water-soluble carbohydrate contents of barley plants treated with 5% LA for 48 h (BALA) decreased, but the resistant starch (RS) and non-fiber carbohydrate contents increased. Moreover, the amount of proteinaceous matrix in BA decreased in response to LA treatment. During in vitro fermentation, BALA had a greater pH but lower dry matter disappearance and ammonia, methane, and short-chain fatty acid levels than BA. The differential metabolites between BA and BALA were clustered into metabolic pathways such as purine metabolism, lysine degradation, and linoleic acid metabolism. Observable differences in ultrastructure between BALA and BA were noted during fermentation. Conclusion: Lactic treatment altered barley nutrient content, including DM, CP, RS, ash, water-soluble carbohydrates and non-fiber carbohydrates, and affected barley ultrastructure. These variations led to significant and incubation time-dependent changes in the in vitro fermentation characteristics and metabolome.

Condensed tannin-induced variations in the rumen metabolome and the correlation with fermentation characteristics in goats.

In this study, we characterized the effects of CT dietary inclusion at 2% (wt/wt) dry matter on the goat rumen metabolome and fermentation characteristics. Barley (BA) and corn (CN) were separately used as basal grain for the control rations, and rations supplemented with CT were BACT and CNCT, respectively. The rations were tested using eight Japanese Shiba × Saanen goats in a replicated 4 × 4 Latin square arrangement (28 days for each period). Ruminal fluid was obtained on day 25 of each period, and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) analysis was performed. Metabolites from BACT against BA and CNCT against CN were mostly associated with purine metabolism. Moreover, BACT against BA showed intensified biosynthesis of unsaturated fatty acids, and CNCT against CN resulted in strengthened amino acid metabolism. Furthermore, strong correlations were observed between rumen NH3 -N and the copy number of total bacteria with most of the differential metabolites. The present paper provides a better understanding of the relationship between the rumen metabolome and fermentation characteristics and supports a shift in concern about using CT as a strategy to manipulate rumen metabolism.

Treatment of corn with lactic acid delayed in vitro ruminal degradation without compromising fermentation: a biological and morphological monitoring study.

Grain processed by lactic acid (LA) is known to improve ruminant growth and health. However, the exact mechanism regarding rumen hydrolysis of LA-treated grain is still ambiguous. This experiment was designed to compare the effects of 5% LA treatment on the trophic and morphological variations in corn and to discover the alternations in ruminal hydrolysis between LA-treated and untreated corn macroscopically and microscopically using in vitro fermentation method. The results showed that, compared with untreated corn (CN), corn treated with 5% LA for 48 h (CNLA) experienced a decrease in the dry matter, albumin fraction, aNDFom, and water-soluble carbohydrate content but an increase in the resistant starch content. The in vitro fermentation showed that the pH of CNLA was higher, but dry matter disappearance was lower than that of CN. Most of the fermentation indices were unaffected, except for decreased iso-butyrate and iso-valerate. The abundances of total bacteria, Prevotella spp., Streptococcus bovis, and Selenomonas ruminantium were higher, but those of Ruminococcus flavefaciens and Ruminococcus albus were lower in CNLA than in CN. There were differences in the scanning electron micrographs between CNLA and CN after 3 h of fermentation. This study suggests that treating corn with LA for 48 h can induce changes in its nutrient composition and alter the bacterial flora during subsequent in vitro fermentation. These changes appeared to be crucial contributors to the beneficial effects observed in rumen fermentation.

Diverse forage improves lipid metabolism and antioxidant capacity in goats, as revealed by metabolomics.

It is well established that promoting the balance of nutrients and plant secondary metabolites (PSM) by feeding diverse forage physiologically improves ruminant production. However, the underlying mechanism remains unclear. To investigate the physiological mechanism related to the improvement of physiological stress tolerance, ruminants were fed diverse forage. Oxidative stress markers were quantified, and serum metabolomics was performed. Six crossbred Shiba wethers (32.8 ± 9.2 kg BW) were arranged in a replicated 3 × 3 Latin square design. The treatments were feeding only Sudan grass hay (100% SDN); feeding a mixture of Sudan grass and alfalfa hay (70:30, SDN-ALF); and feeding a mixture of Sudan grass, timothy grass, and alfalfa hay (35:35:30; SDN-TMT-ALF). Each diet group was fed its specific diet for 21 days with a 14-day adaptation period. Feed intake and digestibility, blood biochemistry, total antioxidant capacity (TAC), and superoxide dismutase (SOD) were analysed. In addition, blood serum metabolites were assessed by liquid chromatography-tandem mass spectrometry. The DM intake and DM, organic matter, and CP digestibility were higher (P < 0.05) in the SDN-TMT-ALF group than in the SDN group. The TAC was higher (P < 0.01) in the SDN-TMT-ALF and SDN-ALF groups (809.51 and 813.7 µM, respectively) than the SDN group (720.69 µM), while the SOD level was unchanged (P = 0.06) among the treatments. Total serum cholesterol and NH3 levels were higher (P < 0.05) in the SDN-TMT-ALF group (89.17 mg/dL and 242.42 µg/dL, respectively) than in the SDN group (71.00 mg/dL and 89.17 µg/dL). Additionally, the levels of nine metabolites in serum differed among the treatments (P < 0.05). Linoleic acid (LA) and cortisone, which are related to LA metabolism and the steroid biosynthesis pathway, were upregulated by the SDN-ALF and SDN-TMT-ALF diets compared to the SDN diet, suggesting the contribution of ALF to altering the metabolites. The levels of hippuric acid, which is a metabolite of phenolic compounds, were higher (P < 0.001) in the animals fed SDN, which contained higher phenolic and luteolin concentrations than the other diets. Pathway analysis suggested that the higher cortisone levels were derived from cholesterol due to upregulated glycolysis metabolism, which was positively related to increased ingestion, digestibility, and serum LA levels in animals given mixed forage. In conclusion, physiological stress tolerance in the animals was regulated by upregulation of LA and steroid hormone metabolism, which was associated with an increase in TAC rather than the ability of the animal to regulate its PSM intake.