Methane reduction by quercetin, tannic and salicylic acids: influence of molecular structures on methane formation and fermentation in vitro.

Plant secondary metabolites (PSMs) can potentially reduce ruminal methane formation. However, related to differences in their molecular structures, it is not yet clear what causes an anti-methanogenic effect. In an in vitro system simulating rumen fermentation, we investigated the impact of eight compounds with distinct chemical characteristics (gallic and salicylic acids, tannic acid, catechin, epicatechin, quercetin, rutin, and salicin) when added to a basal feed (maize silage) at a concentration of 12% of the feed dry matter. After 48 h of incubation in buffered rumen fluid, methane production was significantly lowered by quercetin (43%), tannic acid (39%) and salicylic acid (34%) compared to the control (maize silage alone) and without changes in total volatile fatty acid production during fermentation. No other PSM reduced methane formation as compared to control but induced significant differences on total volatile fatty acid production. The observed differences were related to lipophilicity, the presence of double bond and carbonyl group, sugar moieties, and polymerization of the compounds. Our results indicate the importance of distinct molecular structures of PSMs and chemical characteristics for methane lowering properties and volatile fatty acid formation. Further systematic screening studies to establish the structure-function relationship between PSMs and methane reduction are warranted.

Obesity-Related Metabolome and Gut Microbiota Profiles of Juvenile Göttingen Minipigs-Long-Term Intake of Fructose and Resistant Starch.

The metabolome and gut microbiota were investigated in a juvenile Göttingen minipig model. This study aimed to explore the metabolic effects of two carbohydrate sources with different degrees of risk in obesity development when associated with a high fat intake. A high-risk (HR) high-fat diet containing 20% fructose was compared to a control lower-risk (LR) high-fat diet where a similar amount of carbohydrate was provided as a mix of digestible and resistant starch from high amylose maize. Both diets were fed ad libitum. Non-targeted metabolomics was used to explore plasma, urine, and feces samples over five months. Plasma and fecal short-chain fatty acids were targeted and quantified. Fecal microbiota was analyzed using genomic sequencing. Data analysis was performed using sparse multi-block partial least squares regression. The LR diet increased concentrations of fecal and plasma total short-chain fatty acids, primarily acetate, and there was a higher relative abundance of microbiota associated with acetate production such as Bacteroidetes and Ruminococcus. A higher proportion of Firmicutes was measured with the HR diet, together with a lower alpha diversity compared to the LR diet. Irrespective of diet, the ad libitum exposure to the high-energy diets was accompanied by well-known biomarkers associated with obesity and diabetes, particularly branched-chain amino acids, keto acids, and other catabolism metabolites.

Obesity Development in a Miniature Yucatan Pig Model: A Multi-compartmental Metabolomics Study on Cloned and Normal Pigs Fed Restricted or Ad Libitum High-Energy Diets.

Miniature-pig models for human metabolic disorders such as obesity and metabolic syndrome are gaining popularity. However, in-depth knowledge on the phenotypic and metabolic effects of metabolic dysregulation is lacking, and ad libitum feeding is not well-characterized in these pig breeds. Therefore, an investigation was performed into the metabolome of Yucatan minipigs fed ad libitum or restricted diets. Furthermore, we used cloned and conventional minipigs to assess if cloning reflects a presumably lowered variation between subjects. For 5 months, 17 female Yucatan minipigs were fed either ad libitum or restricted Western-style diets. Serum, urine, and liver tissues were collected and analyzed by non-targeted liquid chromatography-mass spectrometry metabolomics and by biochemical analyses. Several metabolic pathways were deregulated as a result of obesity and increased energy-dense feed intake, particularly the hepatic glutathione pathway and the pantothenic acid and tryptophan metabolic pathways in serum and urine. Although cloned minipigs were phenotypically similar to wild-type minipigs, the metabolomics analysis of serum and liver tissues showed several altered pathways, such as amino acid and purine metabolism. These changes, as an effect of cloning, could limit the use of cloned models in dietary intervention studies and provides no evidence of decreased variability between subjects.

Rye Bran Modified with Cell Wall-Degrading Enzymes Influences the Kinetics of Plant Lignans but Not of Enterolignans in Multicatheterized Pigs.

Background: Whole-grain intake is associated with a lower risk of chronic Western-style diseases, possibly brought about by the high concentration of phytochemicals, among them plant lignans (PLs), in the grains.Objective: We studied whether treatment of rye bran with cell wall-degrading enzymes changed the solubility and kinetics of PLs in multicatheterized pigs.Methods: Ten female Duroc × Danish Landrace × Yorkshire pigs (60.3 ± 2.3 kg at surgery) fitted with permanent catheters were included in an incomplete crossover study. The pigs were fed 2 experimental diets for 1-7 d. The diets were rich in PLs and based on nontreated lignan-rich [LR; lignan concentration: 20.2 mg dry matter (DM)/kg] or enzymatically treated lignan-rich (ENZLR; lignan concentration: 27.8 mg DM/kg) rye bran. Plasma concentrations of PLs and enterolignans were quantified with the use of targeted LC-tandem mass spectrometry. Data were log transformed and analyzed with mixed-effects, 1-compartment, and asymptotic regression models.Results: The availability of PLs was 38% greater in ENZLR than in LR, and the soluble fraction of PLs was 49% in ENZLR compared with 35% in LR diets. PLs appeared in the circulation 30 min after intake of both the ENZLR and LR diets. Postprandially, consumption of ENZLR resulted in a 4-times-greater (P < 0.0001) plasma PL concentration compared with LR. The area under the curve (AUC) measured 0-360 min after ENZLR intake was ∼2 times higher than after LR intake. A 1-compartment model could describe the postprandial increase in plasma concentration after ENZLR intake, whereas an asymptotic regression model described the plasma concentrations after LR intake. Despite increased available and soluble PLs, ENZLR did not increase plasma enterolignans.Conclusion: The modification of rye bran with cell wall-degrading enzymes resulted in significantly greater plasma concentrations of PLs and the 4-h AUC, particularly syringaresinol, in multicatheterized pigs.