Effects of structural and non-structural polysaccharides in the diet of the growing pig on gastric emptying rate and rate of passage of digesta to the terminal ileum and through the total gastrointestinal tract

Abstract

-_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _~_ _~_ _ _ _ _ _ _ _ _ _~~-Six experiments were made in growing pigs to investigate the effects of substituting bran, oatmeal byproduct, pectin and guar gum for barley on gastric emptying rate, pH and dry matter of digesta and on the dry matter content and rate of passage of digesta to the terminal ileum and overall. Twelve pigs with cannulas sited at the pyloric/fundic junction of the stomach were used to measure gastric emptying. Seventy-two pigs were kept in metabolism cages for the total collection of faeces and nine pigs were fitted with simple cannulas 150 mm cranial to the ileo-caecal junction. For the overall transit measurements the barley was ground through a 4.68 mm screen (C) and for the other studies either through this screen or a 1.56 mm screen (F). Gastric emptying rates were significantly faster for F diets than for C diets, but bran and oatmeal by-product substitutions were without significant effect on this variable or on rate of passage to the terminal ileum. Guar gum and pectin significantly speeded up gastric emptying and transit to the terminal ileum in C diets. Guar gum and pectin did not significantly affect overall transit time, but bran accelerated it. The results are discussed in relation to the depressive effects on nutrient utilization which have been recorded for the four polysaccharides: it is postulated that gastric emptying rate and transit time to the terminal ileum are likely to have a minimal effect on overall transit time. Polysaccharides are composed of both structural (cellulose, hemicellulose and pectic substances) and non-structural (gums, mucilages and algal polysaccharides) types. Dietary fibre is usually a mixture of several of these polysaccharides which have different physicochemical properties and different physical characteristics, together with varying proportions of lignin. The aims of the experiments described in the present paper were to study the effects of dietary fibre on gastric emptying rate and rate of passage of digesta to the terminal ileum and through the total gastrointestinal tract, so that an understanding of its mode of action in affecting nutrient digestibility could be furthered. The effects of dietary fibre on gastric emptying rate and rate of passage of digesta in the gastrointestinal tract are likely to be mediated by altering the volumes and physical properties of lumen contents. The emptying rate is also influenced by feedback control from the duodenum via receptors sensitive to the osmolality and acidity of digesta, and to other dietary factors including the particle size of the digesta (Laplace, 1982) which, in barleybased diets, can also affect gastric pH (Lawrence, 1970b). Dietary fibre rich in structural polysaccharides as in bran, and soluble polysaccharides such as guar gum, have been shown to have some effects on gastric emptying rate at various points in time up to 4 h after feeding (Rainbird, 1986; Rainbird & Low, 1986a, 6) V. P O T K I N S A N D O T H E R Semptying the digesta, none were foun...

Differential effects of feeding fermentable carbohydrate to growing pigs on performance, gut size and slaughter characteristics

“…Interestingly, pigs given diet WBL also consumed more S-NSP + RS than pigs given diets SAP+ S-NSP and SAP+ S-NSP + RS (Table 6), yet performed better. The four-to five-fold increase in intake of I-NSP by pigs given WBL most likely expedited the movement of digesta through the gastrointestinal tract, since foodstuffs containing higher concentrations of 1-NSP have a shorter mouth-to-anus transit time than diets containing soluble polysaccharides (Potkins et al, 1991). This mechanism may have reduced the residence time of soluble NSP in the small intestine, and hence reduced the anti-nutritive properties of S-NSP on digestion and absorption.…”

In Situ Prebiotics for Weaning Piglets: In Vitro Production and Fermentation of Potato Galacto-Rhamnogalacturonan

“…The pHs of the stomach and the small intestine were measured to be 4.1 to 4.6 and 6.0 to 7.0, respectively, which are in agreement with those reported in the literature (43). A pH of 3.0 was chosen as the value for the stomach, as this level of acidity is realistic in piglets that have eaten little or after an overnight fast (44,45). Proteolytic activity, which can potentially degrade the pectinolytic enzymes, was added to mimic the measured values, as the values in the literature are not directly applicable due to differences in the methods and the definition of units of activity.…”

Replacement of digestible fibre by starch in the diet of the growing rabbit. I. Effects on digestion, rate of passage and retention of nutrients

“…Conversely, substituting starch for fibre (beet pulps replaced by barley), but associated with a reduction of dietary ADF level, causes a strong reduction of energy and nitrogen retention [15,16]. Compared to low digestible fibres (such as cellulose), pectins (for instance provided by beet pulp) are supposed to slow down the digestive transit in monogastric animals [22,37]. In the rabbit, this effect has been mentioned for the liquid phase between the mouth and ileum [2].…”