Effects of removal of the forestomach and caecum on the utilization of dietary urea in golden hamsters (Mesocricetus auratus) given two different diets

No news from old drawings? Stomach anatomy in muroid rodents in relation to body size and ecology

Muroid rodents mostly have a complex stomach: one part is lined with a cornified (non-glandular) epithelium, referred to as a 'forestomach,' whereas the rest is lined with glandular epithelium. Numerous functions for the forestomach have been proposed. We collated a catalog of anatomical depictions of the stomach of 174 muroid species from which the respective non-glandular and glandular areas could be digitally measured, yielding a 'stomach ratio' (non-glandular:glandular area) as a scale-independent variable. Stomach ratios ranged from 0.13 to 20.15, and the coefficient of intraspecific variation if more than one picture was available for a species averaged at 29.7% (± 21.5). We tested relationships of the ratio with body mass and various anatomical and ecological variables, including diet. There was a consistent phylogenetic signal, suggesting that closely related species share a similar anatomy. Apart from classifying stomachs into hemiglandular and discoglandular, no anatomical or ecological measure showed a consistent relationship to the stomach ratio. In particular, irrespective of statistical method or the source of dietary information, dietary proxies did not significantly correlate with the stomach ratio, except for a trend towards significance for invertivory (insectivory). Yet, even this relationship was not convincing: whereas highly insectivorous species had high but no low stomach ratios, herbivorous species had both low and high stomach ratios. Thus, the statistical effect is not due to a systematic increase in the relative forestomach size with invertivory. The most plausible hypotheses so far associate the muroid forestomach and its microbiome with a generic protective role against microbial or fungal toxins and diseases, without evident correlates of a peculiar need for this function under specific ecological conditions. Yet, this function remains to be confirmed. While providing a catalog of published depictions and hypotheses, this study highlights that the function of the muroid rodent forestomach remains enigmatic to date. This article is protected by copyright. All rights reserved.

Pregastric and caecal fermentation pattern in Syrian hamsters

Few studies have compared the pregastric and caecal digestion of hamsters. Mature Syrian hamsters (

Utilization of dietary urea nitrogen is stimulated by D-mannitol feeding in rabbits

The effect of D-mannitol as an indigestible sugar on apparent digestibility of nutrients, nitrogen (N) utilization and growth performance, have been investigated in growing rabbits fed a urea-containing diet. In experiment 1, 40-day-old male rabbits were fed a commercial diet with urea 10 g/kg with added glucose or D-mannitol 60 g/kg each. Thereafter, in experiment 2 the rabbits aged 55 days were fed a commercial diet with or without urea 10 g/kg. Feed restriction at 55 g/kg(0.75)/day was carried out in both experiments. Addition of D-mannitol to the urea-containing diet decreased urinary N excretion, which consequently increased N retention and ratios of retained N to consumed N or apparently absorbed N. Addition of urea alone to the diet increased daily N intake and urinary N excretion but did not affect N retention. Weight gain and feed efficiency were improved by D-mannitol feeding, whereas feeding with urea alone did not affect these parameters. Utilization of dietary urea was enhanced in growing rabbits fed the urea-containing diet with D-mannitol, resulting in improvement of N retention and growth performance.

Surgical removal of the pregastric pouch reduces voluntary lactose consumption in golden hamsters

Unlike other adult mammals, golden hamsters voluntarily consume substantial amounts of the disaccharide sugar lactose. It was hypothesized that the hamster's readiness to consume lactose depends upon its possession of a pregastric pouch in which ingested lactose is broken down into its constituent monosaccharides, thus preventing the aversive gastrointestinal symptoms that monogastric animals experience following lactose ingestion. Adult golden hamsters underwent either surgical removal of the pregastric pouch or sham surgery. Following recovery from surgery, hamsters were given continuous free access for 14 days to tap water, Purina Rodent Chow, a 24% sugar solution (either lactose or sucrose), and a Purina chow-based diet containing 30% added sugar (for each hamster, the same sugar that was provided in solution). Surgical removal of the pregastric pouch caused a 40% reduction in total lactose consumption: this reduction resulted from equivalent decreases in consumption of the lactose solution and the lactose-containing diet. Pouch removal had no effect on total sucrose consumption, and sham surgery had no effect on either lactose or sucrose consumption. These results support the conclusion that the adult hamster's unusually high level of voluntary lactose consumption depends upon its possession of a pregastric pouch, which plays an important role in lactose digestion.

Comparison of fibre digestion and digesta retention time between rabbits, guinea-pigs, rats and hamsters

1. Digestive efficiencies of fibre components and retention time of digesta in the whole gut and in the large intestine were measured in rabbits, guinea-pigs, hamsters and rats when given a lucerne (Medicago sativa)-containing diet. 2. Co-EDTA and chromium-mordanted cell-wall constituents of Italian ryegrass (Lolium multiflorum L.) were used as liquid- and solid-phase markers respectively. Both markers were mixed with the experimental diet and given after digestion trials. 3. Mean retention times of each marker were calculated from time-course changes in concentrations of the markers in faeces. The mean retention times of the markers in the large intestine were calculated from exponential slopes fitted to the time-course changes of faecal concentrations of the markers. 4. The digestibilities of crude fibre, neutral-detergent fibre and acid-detergent fibre were highest in the guinea-pigs, followed by the hamsters, and lowest in the rabbits and rats. 5. The mean retention times of Cr in the whole tract were longer in the larger animals and shortest in the hamsters. The mean retention times of Cr in the large intestine were longest in the guinea-pig followed by the hamsters and the rats. The rabbits had an extremely short retention time of Cr in the large intestine. 6. These results suggest that the retention time of solid digesta in the large intestine can explain the difference in the digestive efficiencies of fibre components amongst non-ruminant small herbivores whereas retention of digesta in the whole gut is not related to the digestibility of fibre components.

Ingestive behaviour of Syrian hamsters: advantages of the comparative approach

A brief review of laboratory feeding studies in Syrian hamsters (Mesocricetus auratus) is presented. A number of profound behavioural differences between rats and hamsters are noted. One such difference concerns the diurnal organization of energy input and expenditure. It is suggested that several of these differences might be exploited at the level of neurochemical correlates of feeding, and some preliminary studies are summarized. Finally, some unexpected abnormalities in salt and water intake in regard to the actions of angiotensin II are identified as further areas for comparative investigation.

Effect of monensin on feed utilization and gastrointestinal fermentation in the hamster (Mesocricetus auratus)

Three experiments were conducted to examine the effect of monensin on growth performance, feed utilization and volatile fatty acids (VFA) in the forestomach and caecum of hamsters. In Expt 1, monensin was fed at levels of 0, 5, 10 and 20 mg/kg to the growing male and female hamsters given a commercial diet (major component: lucerne (Medicago sativa) meal). In Expt 2, monensin was fed at levels of 0, 5, 15, 45 and 135 mg/kg to the growing male hamsters given a semi-purified diet containing 10 g urea/kg (main components: maize starch, sucrose, casein and cellulose). In Expt 3, monensin was fed at levels of 0 and 40 mg/kg to the growing male hamsters given the commercial diet containing lucerne meal or a semi-purified diet. In Expt 1, monensin improved feed conversion efficiency and growth performances in the young growing hamsters, but monensin did not affect the hamsters at a later growing stage. In response to monensin the proportion of acetic acid increased and that of propionic acid decreased in the forestomach, whereas the proportion of acetic acid decreased and that of propionic acid increased in the caecum in Expt 2. The hamsters given 135 mg monensin/kg ate less, developed diarrhoea and died. The apparent digestibility of crude protein (nitrogen X 6.25) was improved by monensin but those of dry matter and neutral-detergent fibre (NDF) were decreased in hamsters given the semi-purified diet in Expt 3. Monensin did not appear to have a significant effect on the apparent digestibility of the diet containing lucerne meal. The responses to monensin in hamsters are compared with those in ruminants.