The rat as a model for pigs: comparative values for the digestibility of NSP and other macronutrients

Abstract

The present investigation was undertaken to study whether conventional male Wistar rats could be used as a model for pigs with regard to total tract digestibilities of NSP and macronutrients and whether nebacitin-treated rats could be used as a model for small intestinal digestibility in pigs. Nineteen experimental diets prepared from different fractions of wheat and oats, and which all had been evaluated in experiments with ileal cannulated pigs, were used for the present study. There was a close relationship between the total tract digestibilities of organic matter in the two species. The same was the case with regard to the digestibility of total NSP and arabinoxylans, but the values were on average 6 % lower in rats than in pigs. On average, there were no significant differences between rats and pigs with regard to faecal protein digestibility. However, protein in oat-based diets was significantly better digested in the rat than the pig. The digestibility of fat was consistently higher in rats than in pigs, with the biggest difference being found in oat-based diets, in which most of the fat was locked in cell structures. For the wheat-based diets, in which a large proportion of the fat was present as added fat, there was a greater similarity between the two species. In nebacitin-treated rats the digestibility of organic matter, starch, protein and fat was negatively related to the dietary level of NSP, but this model could not be used to predict the small intestinal digestibility of NSP and macronutrients in ileal-cannulated pigs.Digestibility: Non-starch polysaccharides: Protein: Fat: Pigs: RatsThe laboratory rat has been widely used to investigate basic principles of nutrition in single-stomached animals. In contrast to human nutrition, however, the use of rats as models in pig nutrition is less well accepted, because it is relatively easy to obtain results from the pig itself. The great value of the rat as a model lies in the economic factors associated with facilities and time, which allows the use of large numbers of animals and a rapid production of results.The digestibility of energy and protein in the pig and rat is highly correlated for several diets (Eggum, 1973;Eggum et al. 1982), indicating that the rat may be a good model for pigs for these variables. However, it is less clear whether rats are also suitable models for pigs with regard to the digestibility of other nutrients and the fermentation of non-digestible carbohydrates, primarily as NSP, by the gut microflora. Like the pig, rats harbour a permanent bacterial flora in the stomach and small intestine, and similar groups of bacteria were found in the large intestine of both species (Jensen, 1992). However, there are obvious differences between rats and pigs that may be of importance for the microbial fermentation. The relative size of the caecum in rats is bigger than in pigs and the rat may practise coprophagy. Further, the rat is a small animal with a faster transit through the gut, and this can reduce bacterial polysaccharide breakdown co...

Effects of pectin supplementation on the fermentation patterns of different structural carbohydrates in rats

“…The NSP of the diets that mainly originates from ingredients wheat and oats in CONT were not completely fermented after passing the rat intestine. Fecal digestibility of total NSP in CONT diet were comparable to those reported for diets based on wheat and oats . Fermentation of cereal NSP present in CONT led to a high proportion of butyrate, which could be attributed to the stimulating effect of AXs on the production of butyrate, as reported before .…”

Validation of a dual in vivo–in vitro assay for predicting the digestibility of nutrients in humans

“…Alternative methods involving animal models that allow such differentiation are needed. The laboratory rat is a suitable choice for an animal model for humans owing to its low cost and ease of use . The upper gastrointestinal tracts of rats and humans are similar anatomically and both species are omnivorous.…”

Rapeseed and milk protein exhibit a similar overall nutritional value but marked difference in postprandial regional nitrogen utilization in rats

“…We did not observe in this species the low true protein digestibility of RPI that we [4] and others [8,19,20] had previously evidenced in humans or other monogastric species. Rats may benefit from more efficient enzymatic equipment to digest hydrolysis-resistant rapeseed proteins than humans or pigs, and as such, are probably not a good model to study dietary protein digestibility in humans, unlike the pig [9,21], at least for dietary proteins with relatively slight differences in digestibility. In addition, RPI also did not differ from MPI in terms of postprandial metabolic losses of dietary N resulting from the deamination of dietary AA and excretion in urine.…”