C. Chris Calvert

Diet shapes the gut microbiome of pigs during nursing and weaning

BackgroundThe newborn mammal is rapidly colonized by a complex microbial community, whose importance for host health is becoming increasingly clear. Understanding the forces that shape the early community, especially during the nursing period, is critical to gain insight into how this consortium of microbes is assembled. Pigs present an attractive model for nursing humans, given physiological and compositional similarity of pig and human milk and the utility of pigs in experimental studies. However, there is a paucity of data examining the gut microbiome in nursing pigs from birth through weaning using modern molecular methods and fewer experimental studies that examine the impact of diet on these microbial communities.ResultsWe characterized the fecal microbiome of pigs from birth through 7xa0weeks of age, during which the animals were transitioned from an exclusive diet of sow milk to a starter diet composed of plant and animal-based components. Microbial communities were clearly distinguishable based on diet, being relatively stable absent dietary changes. Metagenomic sequencing was used to characterize a subset of animals before and after weaning, which identified glycan degradation pathways differing significantly between diets. Predicted enzymes active on milk-derived glycans that are otherwise indigestible to the host animal were enriched in the microbial metagenome of milk-fed animals. In contrast, the bacterial metagenome of weaned animals was enriched in functional pathways involved in plant glycan deconstruction and consumption.ConclusionsThe gut microbiome in young pigs is dramatically shaped by the composition of dietary glycans, reflected by the different functional capacities of the microbiome before and after weaning.

Phenolic metabolites and substantial microbiome changes in pig feces by ingesting grape seed proanthocyanidins

Proanthocyanidin (PAC) consumption has been linked to better colonic health, but PACs are poorly absorbed, making them a target for colonic metabolism. The resulting metabolites are low molecular weight and could potentially be absorbed. To understand the effects of dietary PACs it would be important to resolve the metabolic issue and link these changes to microbial population changes in a suitable model for human digestion. Here, six crossbred female pigs were fed a diet containing 1% (w/w) of MegaNatural® Gold grape seed extract (GSE) daily for 6 days. Fecal samples were analyzed by normal phase LC coupled to fluorescence detection and LC-MS/ToF. DNA was extracted from pig fecal samples and the V3/V4 region of the 16S rRNA gene was sequenced using an Illumina MiSeq. Intact parent PACs (dimer-pentamer) were observed in the feces on days 3 and 6 at similar high levels (∼400 mg kg(-1) total) during ingestion of GSE but were absent 48 h post-feeding. The major phenolic metabolites were 4-hydroxyphenylvaleric acid and 3-hydroxybenzoic acid which increased by ∼30 and 3 mg kg(-1) respectively. The GSE diet also caused an ecological shift in the microbiome, dramatically increasing Lachnospiraceae, Clostridales, Lactobacillus and Ruminococcacceae. The relationship between dietary PACs and colon health may be attributable to the altered bacterial populations or phenolic compounds in the colon.

Identification of porcine sperm plasma membrane proteins that may play a role in sperm-egg fusion.

Sperm plasma membrane (PM) proteins that demonstrate affinity for egg PM preparations have the potential to be biologically important during sperm-egg binding and/or fusion. In this study four such proteins have been identified. To provide quantitative evidence for possible biological function, the large natural variation among different porcine sperm populations with regard to their ability to interact with the egg was compared with the relative binding of egg PM material to individual proteins. An aliquot from each of 24 porcine ejaculates was evaluated by the zona-free hamster ova bioassay and the remainder processed to yield sperm PM vesicles. Aliquots of sperm PM were solubilised, separated by SDS-PAGE, western blotted and probed with partially purified, biotinylated egg PM protein. Bound egg PM proteins were visualised on western blots by an avidin/biotin/horseradish peroxidase system and analysed by scanning laser densitometry. Four sperm PM proteins (62, 39, 27 and 7 kDa estimated molecular mass) were the predominant binders of egg PM. The amount of egg PM bound to the 62 kDa protein was significantly correlated with the ability of sperm from the 24 ejaculates to penetrate zona-free hamster ova (percentage of ova penetrated, p = 0.01, R = 0.65; number of penetrated sperm per ovum, p = 0.02, R = 0.63).

Body composition and amino acid concentrations of select birds and mammals consumed by cats in northern and central California

The diet of the feral domestic cat consists of primarily birds and small mammals, but the nutritional composition is relatively unknown. Because of the increasing popularity of natural diets for cats and other wild captive carnivores, the purpose of this study was to describe the body composition and AA concentrations of select birds and small mammals in northern and central California: wild-caught mice (n = 7), Norway rats (n = 2), roof rats (n = 2), voles (n = 4), moles (n = 2), gophers (n = 3), and birds (n = 4). Body water, crude fat (CFa), CP, ash, and AA composition for each specimen were determined. Results are reported as mean ± SD. All results are reported on a DM basis except body water (as-is basis) and AA (g/16 g N). Combined, carcasses had this mean composition: 67.35 ± 3.19% water, 11.72 ± 6.17% CFa, 62.19 ± 7.28% CP, and 14.83 ± 2.66% ash. Concentrations of Arg, Tau, Cys, and Met were 5.63 ± 0.46, 0.92 ± 0.33, 1.91 ± 0.89, and 1.82 ± 0.19 g/16 g N, respectively. Using NRC physiologic fuel values for CP, CFa, and carbohydrate by difference, the combined average energy content of the carcasses was 3,929 kcal/kg DM, but the fiber content was not determined. With the exception of mice and rats, little historical data exist regarding the body and AA composition of many of the species analyzed in this study. Wild-caught mice and rats were composed of less fat but more ash compared with previously reported data in their purpose-bred counterparts. The CP content of mice in this study was similar to previous reports in purpose-bred mice. The CP content of rats was similar or slightly greater compared with historical findings in purpose-bred rats. The N content of rats and AA concentrations on a per-N basis for both rats and mice were similar to previously published data on purpose-bred rodents. The discrepancies in nutrient composition, especially fat concentration, indicate that using purpose-bred animals to represent the diet of the feral domestic cat may not be valid in many instances. When consumed to meet energy needs, the nutrient content of the species reported in the present study exceed the NRC (2006) recommended allowances (RA) for total fat, CP, and essential AA for felines at all life stages.

Use of metabolomics and lipidomics to evaluate the hypocholestreolemic effect of Proanthocyanidins from grape seed in a pig model.

SCOPEnThis work aims to evaluate changes in the fecal metabolomic profile due to grape seed extract (GSE) intake by untargeted and targeted analysis using high resolution mass spectrometry in conjunction with multivariate statistics.nnnMETHODS AND RESULTSnAn intervention study with six crossbred female pigs was performed. The pigs followed a standard diet for 3 days, then they were fed with a supplemented diet containing 1% (w/w) of MegaNatural® Gold grape seed extract for 6 days. Fresh pig fecal samples were collected daily. A combination of untargeted high resolution mass spectrometry, multivariate analysis (PLS-DA), data-dependent MS/MS scan, and accurate mass database matching was used to measure the effect of the treatment on fecal composition. The resultant PLS-DA models showed a good discrimination among classes with great robustness and predictability. A total of 14 metabolites related to the GSE consumption were identified including biliary acid, dicarboxylic fatty acid, cholesterol metabolites, purine metabolites, and eicosanoid metabolites among others. Moreover, targeted metabolomics using GC-MS showed that cholesterol and its metabolites fecal excretion was increased due to the proanthocyanidins from grape seed extract.nnnCONCLUSIONnThe results show that oligomeric procyanidins from GSE modifies bile acid and steroid excretion, which could exert a hypocholesterolemic effect.

Computer Modeling of Obesity Links Theoretical Energetic Measures with Experimental Measures of Fuel Use for Lean and Obese Men

The goal of this research was to use a computational model of human metabolism to predict energy metabolism for lean and obese men. The model is composed of 6 state variables representing amino acids, muscle protein, visceral protein, glucose, triglycerides, and fatty acids (FAs). Differential equations represent carbohydrate, amino acid, and FA uptake and output by tissues based on ATP creation and use for both lean and obese men. Model parameterization is based on data from previous studies. Results from sensitivity analyses indicate that model predictions of resting energy expenditure (REE) and respiratory quotient (RQ) are dependent on FA and glucose oxidation rates with the highest sensitivity coefficients (0.6, 0.8 and 0.43, 0.15, respectively, for lean and obese models). Metabolizable energy (ME) is influenced by ingested energy intake with a sensitivity coefficient of 0.98, and a phosphate-to-oxygen ratio by FA oxidation rate and amino acid oxidation rate (0.32, 0.24 and 0.55, 0.65 for lean and obese models, respectively). Simulations of previously published studies showed that the model is able to predict ME ranging from 6.6 to 9.3 with 0% differences between published and model values, and RQ ranging from 0.79 to 0.86 with 1% differences between published and model values. REEs >7 MJ/d are predicted with 6% differences between published and model values. Glucose oxidation increases by ∼0.59 mol/d, RQ increases by 0.03, REE increases by 2 MJ/d, and heat production increases by 1.8 MJ/d in the obese model compared with lean model simulations. Increased FA oxidation results in higher changes in RQ and lower relative changes in REE. These results suggest that because fat mass is directly related to REE and rate of FA oxidation, body fat content could be used as a predictor of RQ.