E.R. Deaville

Interactions of tea tannins and condensed tannins with proteins.

Binding parameters for the interactions of four types of tannins: tea catechins, grape seed proanthocyanidins, mimosa 5-deoxy proanthocyanidins, and sorghum procyanidins (mDP=17), with gelatin and bovine serum albumin (BSA) have been determined from isothermal titration calorimetry data. Equilibrium binding constants determined for the interaction with gelatin were in the range 10(4) to 10(6) M(-1) and in the order: sorghum procyanidins > grape seed proanthocyanidins > mimosa 5-deoxy proanthocyanidins > tea catechins. Interaction with BSA was generally weaker, with equilibrium binding constants of < or =10(3)M(-1) for grape seed proanthocyanidins, mimosa 5-deoxy proanthocyanidins and tea catechins, and 10(4)M(-1) for the sorghum procyanidins. In all cases the interactions with proteins were exothermic and involved multiple binding sites on the protein. The data are discussed in relation to the structures and the known nutritional effects of the condensed tannins.

Prediction of organic matter digestibility in vivo of grass silage by near infrared reflectance spectroscopy: effect of calibration method, residual moisture and particle size

The results of a study into the effects of calibration method, residual moisture content and sample particle size on the prediction of the organic matter digestibility in vivo of grass silages by near infrared reflectance spectroscopy are reported. A total of 182 grass silages with organic matter digestibility values measured with sheep were divided into calibration (103) and validation sets (79) on the basis of their spectral characteristics. Calibrations were developed using modified stepwise regression, modified partial least squares and principal components regression techniques with and without a scatter correction technique to reduce particle size effects. In addition, the use of a noise repeatability file during the calibration process was evaluated for its ability to reduce the effects of variation in sample residual moisture content. The highest predictive ability for organic matter digestibility was obtained using a second order derivative modified partial least squares regression with the use of both scatter correction and noise repeatability procedures. Validation statistics obtained were R2 = 0.82, standard error of prediction 2.35 and slope 1.01. The best calibration was also shown to have acceptable analytical repeatability (2.44) and not to distinguish between silages made in clamps or as big bales wrapped in plastic.

Differential Effects of Two Fermentable Carbohydrates on Central Appetite Regulation and Body Composition

Background Obesity is rising at an alarming rate globally. Different fermentable carbohydrates have been shown to reduce obesity. The aim of the present study was to investigate if two different fermentable carbohydrates (inulin and β-glucan) exert similar effects on body composition and central appetite regulation in high fat fed mice. Methodology/Principal Findings Thirty six C57BL/6 male mice were randomized and maintained for 8 weeks on a high fat diet containing 0% (w/w) fermentable carbohydrate, 10% (w/w) inulin or 10% (w/w) β-glucan individually. Fecal and cecal microbial changes were measured using fluorescent in situ hybridization, fecal metabolic profiling was obtained by proton nuclear magnetic resonance (1H NMR), colonic short chain fatty acids were measured by gas chromatography, body composition and hypothalamic neuronal activation were measured using magnetic resonance imaging (MRI) and manganese enhanced MRI (MEMRI), respectively, PYY (peptide YY) concentration was determined by radioimmunoassay, adipocyte cell size and number were also measured. Both inulin and β-glucan fed groups revealed significantly lower cumulative body weight gain compared with high fat controls. Energy intake was significantly lower in β-glucan than inulin fed mice, with the latter having the greatest effect on total adipose tissue content. Both groups also showed an increase in the numbers of Bifidobacterium and Lactobacillus-Enterococcus in cecal contents as well as feces. β- glucan appeared to have marked effects on suppressing MEMRI associated neuronal signals in the arcuate nucleus, ventromedial hypothalamus, paraventricular nucleus, periventricular nucleus and the nucleus of the tractus solitarius, suggesting a satiated state. Conclusions/Significance Although both fermentable carbohydrates are protective against increased body weight gain, the lower body fat content induced by inulin may be metabolically advantageous. β-glucan appears to suppress neuronal activity in the hypothalamic appetite centers. Differential effects of fermentable carbohydrates open new possibilities for nutritionally targeting appetite regulation and body composition.

The effect on voluntary feed intake, in vivo digestibility and nitrogen balance in sheep of feeding grass silage or pea–wheat intercrops differing in pea to wheat ratio and maturity

Adesogan, A.T., Salawu, M.B., Deaville, E.R. (2002). The effect on voluntary feed intake, in vivo digestibility and nitrogen balance in sheep of feeding grass silage or pea?wheat intercrops differing in pea to wheat ratio and maturity. Animal Feed Science and Technology, 96, (3-4), 161-173. Sponsorship: Milk Development Council

The nutritive value and chemical composition of energy-rich by-products for ruminants

The nutritive value and chemical composition of 29 energy-rich by-products are reported. These comprised two samples of imported dried citrus pulp, one of UK-produced dried citrus pulp, eight of locust bean meal, two of maize gluten feed, one of pearled barley offal, eight of rice bran, two of soya bean hulls, four of molassed sugar beet feed and one of unmolassed sugar beet feed. The crude protein (CP) content of the feedstuffs ranged from 44 to 217 g kg−1 dry matter (DM), the lowest value being for locust bean meal and the highest for maize gluten feed. Total carbohydrates, calculated as the sum of neutral detergent fibre (NDF), water-soluble carbohydrates (WSC) and starch contents, accounted for approximately 510–859 g kg−1 DM for all the feed types studied, and the highest value was found for rice bran, owing to a high starch content (219 g kg−1 DM). The digestible organic matter in the DM (DOMD) contents measured in vivo were all within the range 686–838 g kg−1, with the exception of rice bran and locust bean meal, which had much lower digestibilities (512 g kg−1 and 623 g kg−1, respectively). The metabolisable energy (ME) content of the feedstuffs varied over a relatively wide range (8.2–13.2 MJ kg−1 DM), the lowest value being for rice bran and the highest for UK-produced dried citrus pulp. The ME content of all the feedstuffs studied was predicted from a relationship with neutral detergent amylase-cellulase (NCD, g kg−1 DM) and acid ether extract (AEE, g kg−1 DM) as independent variables: ME = 0.0142NCD + 0.0262 AEE, rsd = 1.19.

Regions of normalised near infrared reflectance difference spectra related to the rumen degradation of fresh grass, grass silage and maize silage

Abstract The chemical composition and in situ rumen degradability of dry matter (DM) was determined on five samples each of fresh grass, grass silage and maize silage. After rumen incubation (for 0, 3, 8, 16, 24, 45 and 72 h) the normalised and detrended (SNV-D) near infrared reflectance spectra of the dried, milled forage residues were obtained. For each forage the SNV-D spectra of the 0-h incubation (i.e., washed in water only) was subtracted from the spectra relating to the other incubation periods. The SNV-D difference spectra obtained were compared with the DM degradability data and with the SNV-D spectra measured on cellulose, extracted lignin, starch, glucose, sucrose and fructose. In all forages, spectral regions associated with low degradability were in the 1620 to 1690 nm and 2170 to 2290 nm bands and these corresponded well with the SNV-D spectra of extracted lignin. Spectral regions associated with high degradability (1430 to 1630 nm; 2020 to 2190 nm (2230 in grasses)) were in good agreement with the SNV-D spectra of cellulose and various sugars. Correlations between spectral peak amplitude and rate of peak height change with the extent and rate of DM degradation respectively were weak although a negative correlation (−0.48) was observed between peak amplitude around 2250 nm and the extent of degradation of the insoluble DM. It was concluded that SNV-D difference spectra can describe the time course of rumen degradation of these forages and that spectral regions associated with low degradability are most likely related to lignin. However, further nutritional interpretation of these spectra may be limited because of, for example, the similar and overlapping absorption wavelengths of various carbohydrates whose nutritional value may be different.

Prebiotic Potential of a Maize-Based Soluble Fibre and Impact of Dose on the Human Gut Microbiota

Dietary management of the human gut microbiota towards a more beneficial composition is one approach that may improve host health. To date, a large number of human intervention studies have demonstrated that dietary consumption of certain food products can result in significant changes in the composition of the gut microbiota i.e. the prebiotic concept. Thus the prebiotic effect is now established as a dietary approach to increase beneficial gut bacteria and it has been associated with modulation of health biomarkers and modulation of the immune system. Promitor™ Soluble Corn Fibre (SCF) is a well-known maize-derived source of dietary fibre with potential selective fermentation properties. Our aim was to determine the optimum prebiotic dose of tolerance, desired changes to microbiota and fermentation of SCF in healthy adult subjects. A double-blind, randomised, parallel study was completed where volunteers (n = 8/treatment group) consumed 8, 14 or 21 g from SCF (6, 12 and 18 g/fibre delivered respectively) over 14-d. Over the range of doses studied, SCF was well tolerated Numbers of bifidobacteria were significantly higher for the 6 g/fibre/day compared to 12g and 18g/fibre delivered/day (mean 9.25 and 9.73 Log10 cells/g fresh faeces in the pre-treatment and treatment periods respectively). Such a numerical change of 0.5 Log10 bifidobacteria/g fresh faeces is consistent with those changes observed for inulin-type fructans, which are recognised prebiotics. A possible prebiotic effect of SCF was therefore demonstrated by its stimulation of bifidobacteria numbers in the overall gut microbiota during a short-term intervention.

The effect of fertiliser nitrogen on the solubility and rumen degradability of dry matter and nitrogen in wheat grain

Seventy-four samples of wheat grain (c.v. Mercia) grown under a variety of different fertiliser nitrogen (N) regimes were milled through a 3 mm screen. The rumen degradation characteristics of dry matter (DM) and N were estimated using the polyester bag in situ technique and DM and N solubility in water was estimated in the laboratory. The values determined in situ for the immediately soluble (a) fraction for N (16.9 ± 3.81%) and the rate (c) of N degradation (0.128 ± 0.0178 h−1) were both considerably lower than in previous reports in the literature. The N content of the grain exhibited a strong curvilinear relationship with the total amount of N applied as fertiliser. Increasing fertiliser N and the resulting increase in grain N contents tended to reduce and increase (P < 0.01) the immediately soluble and insoluble but degradable N fractions respectively, although the relationships only accounted for about 10% of the variance. For both statistical and theoretical reasons these relationships may not be applicable to other samples of wheat. The work also showed that the water soluble DM measured in the laboratory was about ten times lower than the immediately soluble DM measured in situ. A similar, but less pronounced effect was seen for N where soluble N was on average only about 0.4 of the in situ zero hour loss (21.2 ± 4.49%) and about 0.5 of the fitted a value (16.9 ± 3.81%). This suggests that the in situ technique can seriously overestimate the immediately soluble DM and N fractions of wheat and probably other cereal grains.

Post-genomics approaches towards monitoring changes within the microbial ecology of the gut

The human gut microbiota, comprising many hundreds of different microbial species, has closely co-evolved with its human host over the millennia. Diet has been a major driver of this co-evolution, in particular dietary non-digestible carbohydrates. This dietary fraction reaches the colon and becomes available for microbial fermentation, and it is in the colon that the great diversity of gut microorganisms resides. For the vast majority of our evolutionary history humans followed hunter-gatherer life-styles and consumed diets with many times more non-digestible carbohydrates, fiber and whole plant polyphenol rich foods than typical Western style diets today.

Wheat Bran Cereal, Human Gut Bacteria and Subjective Wellbeing

Research has shown that consumption of high fiber breakfast cereal is associated with improved subjective well-being, especially increased energy. One possible explanation of these results is through metabolism by gut bacteria and concomitant production of metabolites that influence psychological and gastrointestinal (GI) welfare. This was examined in the present study to determine whether consumption of wheat bran could modulate the composition of the GI microbiota. This human volunteer study (20 volunteers) involved the comparison of three breakfast cereals, All-Bran, Bran Flakes and Cornflakes (60 g/d). The study involved a 14-day baseline phase (no breakfast cereals) and an eight-week experimental phase. Each cereal was consumed for 14 days. A seven-day washout period (no cereals) was carried out between each successive cereal condition. Faecal samples were collected every seven days. Enumeration of predominant faecal bacterial populations (bacteroides, bifidobacteria, clostridia, lactobacilli and eubacteria) was carried out using the culture independent fluorescent in situ hybridisation (FISH) technique. Faecal short chain fatty acid content was also determined. The volunteers completed a battery of questionnaires to assess fatigue/energy, subjective mood, physical and mental health, bowel function and fiber intake. The results showed that in general there was no overall significant effect of breakfast cereal type on the faecal bacterial populations studied. There was also no major effect of breakfast type on short chain fatty acid content. The high-fiber conditions (All-Bran and Bran Flakes) were associated with less fatigue, a significant reduction in cognitive difficulties, looser stools, more motions and feeling more energised.