Gordon W. Reynolds

The effect of dietary peptide concentration on endogenous ileal amino acid loss in the growing pig

The aim of the present study was to determine whether dietary peptide concentration had an effect on endogenous ileal amino acid flow in the growing pig. Eight 33 kg live weight entire male pigs had post-valve T-caecum (PVTC) cannulas surgically implanted for the collection of ileal digesta. The pigs were fed twice daily at 100 g/kg metabolic body weight per d and were given diets containing enzyme-hydrolysed casein (EHC) at 0, 50, 100 and 200 g/kg in a Latin-square design. A basal casein-based diet was fed to the pigs for 6 d periods between receiving the experimental diets. The pigs received the experimental diets for 8 d periods, with continuous collection of digesta for 24 h on each of the fifth and eighth days. The endogenous ileal amino acid flows were determined with reference to recovery of the marker, Cr, directly for pigs receiving the protein-free diet or after centrifugation and ultrafiltration (10,000 Da molecular mass cut-off) for pigs on the EHC-based diets. Mean endogenous ileal N flows were 1753, 1948, 2851 and 5743 micrograms/g DM intake when the pigs received diets containing 0, 50, 100 and 200 g EHC/kg respectively. There was a significant (P < 0.05) effect of dietary peptide concentration on the endogenous ileal flows of N and all of the amino acids, with an increase in endogenous ileal amino flow with increasing dietary EHC concentration.

Infection of sheep with adult and larval Ostertagia circumcincta: effects on abomasal pH and serum gastrin and pepsinogen

Infection of sheep with adult or larval O. circumcincta increased serum pepsinogen and gastrin and abomasal pH. The upper limits of the normal range, calculated from over 1000 samples collected from parasite-naive sheep, were set at 2 standard deviations above the mean; these were for serum pepsinogen, 454 mU tyrosine l-1; serum gastrin, 64 pM and abomasal pH, 3.26. Five infection regimes were used: sheep previously exposed to field parasitism were infected with 30,000 larvae intraruminally (Group A), while parasite-naive sheep were administered either 50,000 larvae intraruminally (Group B), 150,000 larvae intraruminally followed by a trickle infection of 10,000 larvae thrice weekly from days 21 to 45 (Group C), 150,000 exsheathed larvae via an abomasal cannula (Group D) or 15,000 adult worms via an abomasal cannula (Group E). Whereas the presence of adult worms rapidly increased serum pepsinogen (after 8 h) and abomasal pH and serum gastrin (after about 19 h), the early infective larval stages, regardless of the infection regime, had minimal effects until the abrupt rise in all parameters 5-6 days after infection. Abomasal pH returned to near normal levels when the infections became patent and was not re-elevated by a subsequent trickle infection, whereas serum gastrin and pepsinogen remained high. The initial hypergastrinaemia was coincident with the increased abomasal pH, but was preceded by the increase in serum pepsinogen. In several sheep, serum pepsinogen increased very little during the parasitism, although there were typical effects on abomasal pH and serum gastrin. Serum gastrin was depressed when the abomasal pH exceeded about 5.5. It is suggested that an inhibitor of gastrin release is generated by proliferating abomasal microbes under these conditions and that this is a limitation to the use of elevated serum gastrin in the diagnosis of parasitism in individual sheep.

Infection of sheep with adult and larval Ostertagia circumcincta: abomasal morphology.

The infection of parasite-naive sheep with approximately 15,000 adult Ostertagia circumcincta via abomasal cannulae resulted in marked changes in the structure and function of the abomasum. The functional changes, which have been characterised previously, included elevated abomasal pH and increased serum concentrations of pepsinogen and gastrin. Eight days after the transplant of adult worms, the abomasa of recipient animals were significantly heavier than those of controls (P < 0.001), the thickness of the fundic mucosa was greater (P < 0.01), there were fewer parietal cells (P < 0.01) and increases in the numbers of mitotic figures and mucus-producing cells. Mucous cell hyperplasia was also evident in the fundic mucosae of sheep receiving a trickle infection of infective, third-stage O. circumcincta larvae and was prominent within nodules associated with larval development. In non-nodular mucosa, there was hyperplasia of mucous cells and changes in the distribution of parietal cells. Decreases in the number of parietal cells at the gland base were offset by increases at a mid-gland level, probably due to chronic hypergastrinaemia, so that, overall, total parietal cell number was unaffected. Mucous cell hyperplasia and the diminution of parietal cell number are seen in a diverse range of disease states and may be mediated by host growth factors such as Transforming growth factor-alpha. Alternatively, the cellular and/or the secretory changes in response to the presence of adult worms are mediated by chemicals that are cytotoxic/inhibitory for parietal cells, and released by the parasites themselves.

Changes in gastrointestinal mucosal mass and mucosal and serum gastrin in sheep experimentally infected with ostertagia circumcincta

Abstract Experimental infection of lambs and sheep caused increases in serum gastrin, abomasal content of gastrin and abomasal mucosal mass. In the sheep, but not the lambs, the small intestinal mucosal mass was also increased. Effects were more on the mucosa of the body than on the antrum of the abomasum. Other regions of the stomach were not affected. The increased gastrin content in lambs was due to similar tissue concentrations (to those in control uninfected animals) in a larger mass of antral mucosa. In the sheep in which the parasitism caused greater increases (than in lambs) in serum gastrin and plasma pepsinogen, the tissue concentration of gastrin was also significantly increased. The duodenal content of gastrin was not altered in infected lambs but was decreased in the sheep compared with uninfected control animals. The importance of the constant stimulus to gastrin secretion in ostertagiasis is discussed, as is the contribution the hypergastrinaemia makes to the hyperplastic changes in the parasitism.

Lycopene bioaccessibility and starch digestibility for extruded snacks enriched with tomato derivatives.

To improve the nutritional value of energy-dense extruded snacks, corn grits were replaced with tomato paste and/or tomato skin powder at ratios of 5, 10, and 20% and extruded to make expanded snack foodlike products. Using a model digestion system, lycopene bioaccessibility and uptake from the snacks into Caco-2 cells were determined. The digestibility of the starch, the main nutrient component of the snacks, was also investigated. While extrusion cooking reduced the lycopene content of the snacks, the proportion of bioaccessible lycopene increased. Lycopene uptake by the Caco-2 cells from the extruded snacks exceeded that of the control in which the lycopene was not extruded, by 5% (p < 0.05). The digestibility of starch in the snacks varied depending on the type of tomato derivative and its concentration. Optimization of the extrusion cooking process and the ingredients can yield functional extruded snack products that contain bioavailable lycopene.

Infection of sheep with adult and larval Ostertagia circumcincta: gastrin

Gastric endocrine cell populations and serum and tissue gastrin have been examined in sheep which were infected either intraruminally by tube with 150,000 Ostertagia circumcincta larvae followed by a trickle infection of 10,000 larvae thrice weekly for 8 weeks or by the transfer of 15,000 adult worms directly into the abomasum and killed 8 days later. Depletion of both antral gastrin and somatostatin was evident in both groups: tissue gastrin concentrations were reduced by 85% in the trickle infection and both G cells (gastrin-containing) and D cells (somatostatin-containing) were pale and fewer after adult worm transfer. The concurrent depletion of antral gastrin and somatostatin supports the contention that the hypergastrinaemia in parasitised sheep is largely secondary to the increase in abomasal pH. Although there was no change in the proportions of G34 and G17 in the tissues, there was an increase in the longer form of gastrin in the circulation of the larval-infected sheep, suggesting that there may be differential secretion of G17 and G34 which may be exaggerated as the rate of secretion increases. Although the fundic mucosa was thicker following trickle infection, there was no evidence of enterochromaffin-like cell hyperplasia in either infected group. It is suggested that hyper-gastrinaemia may be beneficial to the host, as it may allow the abomasum to regain the ability to acidify its contents during continued exposure to the parasites.

Characterisation of the contractile dynamics of the resting ex vivo urinary bladder of the pig.

To characterise the area and movements of ongoing spontaneous localised contractions in the resting porcine urinary bladder and relate these to ambient intravesical pressure (Pves), to further our understanding of their genesis and role in accommodating incoming urine.

Post-weaning effects of milk and milk components on the intestinal mucosa in inflammation.

Many milk-derived components have immunomodulatory and anti-inflammatory properties, and some of these reduce intestinal inflammation when orally administered to animal models of colitis. However, the potential for ruminant milk or milk components to benefit people with intestinal inflammatory disorders (such as Inflammatory Bowel Disease) has not been well-researched. This review describes published research into mechanisms by which ruminant milk and its components may have beneficial effects when consumed by people who have intestinal inflammation.

Effect of the duration of feeding of a protein‐free diet on endogenous ileal nitrogen and amino acid loss in the growing pig

The aim of the study was to determine whether endogenous nitrogen and amino acid excretions at the terminal ileum change over time in the growing pig fed a protein-free diet for 8 days. Seven entire male pigs with an overall mean live weight of 81.6 kg (SEM 3.3 kg) and surgically implanted post-valve T caecum cannulas were fed a semi-synthetic casein-based diet for 8 days. Food was withheld from the pigs for 24 h, after which they were fed a protein-free diet for a further 8 days at a rate of 10% of metabolic body weight per day. Chromic oxide was included in the protein-free diet as an indigestible marker. Ileal digesta were collected continuously from 13:00 to 18:00 h on each day of the experimental period. Endogenous ileal nitrogen flows were determined for each pig each day the protein-free diet was given, and endogenous ileal amino acid flows for the first and eighth days. There were no significant (P > 0.05) effects of the duration of feeding of the protein-free diet on endogenous ileal total nitrogen or amino acid flows, except for the amino acids glycine and cysteine, the flows of which significantly decreased over the 8 day period (P < 0.01 and P < 0.05 for glycine and cysteine respectively), from (mean ± SEM) 1639 ± 217 to 892 ± 212 µg g−1 dry matter intake (DMI) for glycine and from 173 ± 13 to 127 ± 19 µg g−1 DMI for cysteine. The relative contributions (moles of each amino acid as a proportion of total moles of amino acids) of threonine, glycine and cysteine decreased significantly (P < 0.05) and that of proline increased significantly (P < 0.05) during the 8 days that the protein-free diet was fed to the pigs. © 2000 Society of Chemical Industry

Spatiotemporal organization of standing postprandial contractions in the distal ileum of the anesthetized pig.

Spatiotemporal (ST) mapping has mainly been applied to ex vivo preparations of the gut. We report the results of ST mapping of the spontaneous and remifentanil‐induced motility of circular and longitudinal muscles of the distal ileum in the postprandial anaesthetized pig.