Ei Sakaguchi

Role of the furrow of the proximal colon in the production of soft and hard feces in nutrias, Myocastor coypus.

Abstract The bacterial level of soft feces is higher than that of hard feces in nutrias. This suggests the heterogeneity of bacterial density in the large intestine. To show the heterogeneity of bacteria in the contents of the large intestine in nutrias, we divided the contents of the large intestine into 12 regions, then measured the nitrogen (N), total amino acids (TAA) and diaminopimelic acid (DAP), a bacterial marker, of these regions. Levels of N, TAA and DAP varied along the cross section of the proximal colon. The greater curvature of the main lumen and furrow had higher N, TAA and DAP concentrations than the lesser curvature. We also examined the involvement of the furrow in producing two types of feces differing in bacterial nitrogen content by surgically preventing the flow of the furrow contents. We compared the concentrations of N, TAA and DAP between soft and hard feces among operated, sham-operated and intact animals. Surgical closure of the furrow abolished the difference in levels of N, TAA and DAP between soft and hard feces, suggesting that the furrow of the proximal colon is responsible for making the bacterial density higher in soft feces than in hard feces.

Digesta retention and fibre digestion in brushtail possums, ringtail possums and rabbits.

1. Mean retention times (MRTs) of fluid (marked with Co-EDTA), fine particles (mordanted with Yb) and large particles (mordanted with Cr) were measured in brushtail possums (Trichosurus vulpecula), ringtail possums (Pseudocheirus peregrinus) and laboratory rabbits fed semipurified diets. 2. In brushtail possums there were no significant differences in MRT among the three digesta markers. 3. In ringtail possums MRTs of the fluid and fine particle markers were approximately twice that of the large particle marker, indicative of selective retention of both fluid and fine particles in the caecum. 4. In the rabbit MRT of fine particles was also greater than that of large particles, again indicative of selective retention of fine particles in the caecum. 5. Fibre digestibility was greater in the rabbits than in the ringtail possums, and greater for neutral-detergent fibre (including agar) but less for acid-detergent fibre in the rabbits than in the brushtails. Differences in fibre digestibility between brushtails and rabbits were explained by differences in patterns of digesta flow. However, the higher digestibilities of fibre in the rabbits than in the ringtail possums could not be explained on a similar basis.

Behaviors and nutritional importance of coprophagy in captive adult and young nutrias (Myocastor coypus)

Abstract To estimate the contribution of coprophagy to protein intake, we observed the behavior, particularly that associated with coprophagy, in adult and young captive nutrias (experiment 1), and analyzed chemical composition and amino acid composition, including diaminopimeric acid (DAP), an indication of bacterial-deprived protein, of soft feces, entire hard feces, and the black part and green part of hard feces (experiment 2). Nutrias practiced coprophagy 48 times per 24 h in adults, and 28 times in young animals, which not only had a 24-h rhythm but also had 1-h or 2-h short-term rhythms. Nutrias ingested food and drank water vigorously after sunset, following which they practiced coprophagy from midnight to morning, before lying down for much of the day. When coprophagy was prevented we sampled soft feces, produced from midnight to noon, which had high (P < 0.05) concentration of crude protein (CP), DAP on a dry matter (DM) basis and 13 amino acids on a 16 g N basis than hard feces, and had a low (P < 0.05) content of acid detergent fiber (ADF). CP was greater in the black part than the green part of hard feces (P < 0.05) although ADF was less (P < 0.05). The chemical composition of the black part of hard feces was not significantly different from that of soft feces. The dry weight of soft feces excreted in experiment 1 was 34.5 g and 9.7 g DM per 24 h in adult and young animals, respectively. Using this value, the contribution of soft feces to CP intake in adult nutrias was estimated as 16%, superior to that obtained in rabbits for a diet with similar ADF concentration. To Met and Lys intake the contribution of soft feces was 26% and 19%, respectively in adult animals. These results suggest that coprophagy is quite an effective manner for nutrias to ingest extra protein.

Transport of bacteria across and along the large intestinal lumen of guinea pigs

Flow cytometry was used to observe the transport of fluorescently labelled viable bacteria in the large intestinal lumen of guinea pigs after the injection of the bacteria into the proximal colon. Bacteria were transported along the radial and longitudinal axes of the intestine and were separated from dietary residue, accumulated, and then transported back to the caecum. These observations, together with the heterogeneous distribution of bacterial species and chemical composition across and along the large intestine, suggest that there are several different microenvironments within the intestinal lumen between which bacteria and/or dietary residues move. The existence of different microenvironments within the intestinal lumen is consistent with poor mixing of the digesta within the large intestine of pigs and chickens.

Fibre digestion and digesta retention from different physical forms of the feed in the rabbit.

1. Digestibility of fibre was higher in guinea-pigs than in rabbits, however, the digestibility of hemicellulose fraction containing agar was similar in both animals. 2. The digestibility of fibre of a fine particle diet was higher than that of a large particle diet in the rabbit permitted coprophagy, whereas it was lower in the rabbit prevented from coprophagy. 3. The fine particle diet tended to cause shorter retention time of digesta in the rabbit prevented from coprophagy. 4. These suggest that the digestibility of fine components relates to their physical properties which affect the retention time of digesta in the rabbit.

Fibre digestion and digesta retention time in guinea-pigs (Cavia porcellus), degus (Octodon degus) and leaf-eared mice (Phyllotis darwini)

1. Digestibilities of feed and turnover time (1/k), Transit time (TT) and mean retention time (MRT: 1/k + TT) of fluid and particle markers were measured in the guinea-pig (Cavia porcellus), degu (Octodon degus) and leaf-eared mouse (Phyllotis darwini) fed a diet containing 50% alfalfa. 2. The digestibility of fibre and the retention time of digesta were highest in the guinea-pig followed by the degu and lowest in the leaf-eared mouse. 3. The difference in the retention time of digesta, resulting from the variation in the digestibility of fibre, between the three animals can be considered to be related to their body mass.

Mannitol improves absorption and retention of calcium and magnesium in growing rats

OBJECTIVE Resistant sugars, which have several desirable properties, are often used in food production and the pharmaceutical industry. We evaluated the effects of mannitol on the absorption and retention of calcium (Ca) and magnesium (Mg) in growing rats. METHODS In experiment 1, 4-wk-old growing male Wistar rats were given a control diet (C) or mannitol diets containing 2%, 4%, 6%, or 8% mannitol (2M, 4M, 6M, or 8M, respectively) for 28 d to measure the absorption and retention of Ca and Mg. In the last 7 d of the feeding trial, the non-absorbable marker chromium-mordant cellulose was added to the experimental diets to estimate Ca and Mg absorbability in the intestinal segments. In experiment 2, 9-wk-old growing male Wistar rats were fed for 7 d with the experimental diets (C, 4M, or 8M) to observe cecal parameters. RESULTS Apparent Ca absorption and retention in bone were significantly increased by 6M and 8M. Apparent Mg absorption was significantly increased by 4M, 6M, and 8M, whereas Mg retention in bone was significantly increased by 8M. The Ca/Cr and Mg/Cr in cecal digesta were similar in all groups. Fecal Ca/Cr was significantly decreased by 6M and 8M and Mg/Cr was significantly decreased by 4M, 6M, and 8M. In experiment 2, cecal weight and tissue weight were significantly increased by 8M. A significant decrease in pH was concomitant with a significant change in cecal organic acid concentrations after mannitol consumption. CONCLUSION Absorption and retention of Ca and Mg are promoted by mannitol feeding through the fermentation of mannitol in the cecum.

Digesta Passage Time, Digestibility, and Total Gut Fill in Captive Japanese Macaques ( Macaca fuscata ): Effects Food Type and Food Intake Level

Digestion is an important process in understanding the feeding ecology of animals. We examined digesta passage time, digestibility, and total gut fill in Japanese macaques (Macaca fuscata; n = 4) under 4 dietary conditions representing the seasonal and regional variations in the diets of wild populations to determine the effects of food type and food intake on these digestive features. Food type is associated with mean retention time (MRT), digestibility, and total gut fill. Dry matter intake (DMI) of food correlates positively with total gut fill but not with MRT or digestibility. Conversely, indigestible DMI affected MRT negatively. Thus, when Japanese macaques consume high-fiber foods, MRT becomes shorter and digestibility is lower than when eating low-fiber foods. Moreover, macaques experience increases in total gut fill when they consume high-fiber diets or a large amount of food. Japanese macaques may excrete difficult-to-digest food components quickly; they nevertheless buffer an increase in food intake by an increase in gut fill. Our study offers new insights into the relationship between feeding ecology and nutritional physiology in primates by simultaneously examining the effects of food type and intake level on MRT and digestibility.

Effect of indigestible sugars on nitrogen utilization in adult rabbits.

To determine the effects of indigestible sugars on the digestibilities of nutrients and utilization of nitrogen (N) in adult male rabbits, 12 rabbits with or without a collar that prevented cecotrophy were fed experimental diets for 8 days, comprising 3 days for adaptation and 5 days for collection of feces and urine. The experimental diets were formulated by adding D-mannitol or citrus pectin to a commercial diet at 60 g/kg. In the rabbits allowed cecotrophy, mannitol increased the absorption of crude ash but did not significantly alter the digestibilities of crude protein (CP), dry matter and acid-detergent fiber. By contrast, the digestibility of CP was decreased by pectin. The ratios of retained N to consumed N and absorbed N were elevated by mannitol. In the rabbits prevented from cecotrophy, mannitol had no effect on N retention, but increased the N content of cecotrophs (soft feces) and the ratio of the N content of cecotrophs to consumed N. Pectin did not have any significant influences on N retention and the N content of cecotrophs. These results suggest that D-mannitol stimulates cecal microbial proliferation, thereby improving N utilization in rabbits.

Cecal Succinate Elevated by Some Dietary Polyphenols May Inhibit Colon Cancer Cell Proliferation and Angiogenesis

This study demonstrated that 0.5% dietary rutin, ellagic acid, or curcumin markedly increased cecal succinate levels in rats fed a high-fat diet, whereas catechin, caffeic acid, and quercetin did not. Other organic acids were modestly or hardly affected by polyphenols. To clarify the effects of succinate levels increased by polyphenols, this study examined the effects of succinate on the growth and proliferation of colon cancer cells and angiogenesis. The growth and proliferation of HT29 human colon cancer cells and angiogenesis in an ex vivo model were significantly inhibited by succinate at a dose close to that in the cecum of rats fed polyphenols. Furthermore, succinate inhibited the migration of human umbilical vein endothelial cells. These findings suggest that the consumption of some polyphenols affects the health and diseases of the large intestine by elevating succinate.