carbohydrates

carbohydrates are classified based on their molecular structure

• simple sugars: monosaccharides (glucose) and disaccharides (sucrose)

• polysaccharides: starches and fibers

  • starches are carbohydrates that are digested by the animal’s digestive enzymes

  • fibers are carbohydrates that are fermented by the animal’s intestinal microbes

carbohydrates are classified based on speed of fermentation

digestion and absorption of carbohydrates

monogastric animals do not have a dietary requirement for carbohydrates

• the main function of carbohydrates is as a source of energy mainly as glucose

• monogastric animals do not have a requirement for dietary carbohydrates whereas ruminants and hind guy fermenters do

• all glucose requirements could be met through gluconeogenesis from amino acids in monogastric animals

simple carbohydrates and starches function in foods

• there is some evidence to suggest that when energy needs are high, carbohydrates may provide a quick source of energy (included up to 20% of diet)

  • carbohydrate requirement only when protein in diet is low (26% CP)

  • when given enough protein (51% CP) there is no requirement

• the other reason is to help in food processing (binder)

• virtually most companion animal foods contain some starch

  • grains: corn, rice, wheat, barley, oats

• when carbohydrates are used, they should be cooked

  • digestibility of carbohydrates is improved with cooking

  • this is not a problem in commercial diets since most are extruded at high temperatures

• dogs tolerate dietary carbohydrates more than cats

• sugars may also be added to enhance:

  • food palatability: semi-moist cat foods use mono and disaccharides

  • food texture, moisture content, and prevent spoilage

• foods with gravies and sauces contain dextrins, corn syrup, and starches

• sucrose is not used because dogs and cats taste buds are not like our taste buds

fibers’ function in foods

• water soluble cellulose derived substances like carboxymethylcellulose, methylcellulose, and hydropropylcellulose are used as stabilizers, thickeners, and emulsifiers

• cellulose may also be added:

  • for weight management: to reduce the energy density of the food when weight reduction is needed

  • diarrhea and constipation: increase bulk and regulate transit time

  • promote healthy fermentation in the large intestine

• fermentation of fibers produce short-chain fatty acids

  • decrease pathogenic intestinal bacteria

  • reduce colonization by pathogenic bacteria

  • prevention and recovery from intestinal disorders

• fibers that improve beneficial bacteria are called prebiotic fibers

• prebiotics index is an in vitro measure of prebiotic efficacy

  • PI = (bifidobacteria) - (bacteroides) + (lactobacillus) - (clostridia)

many substances have prebiotic activity

• mannanoligosaccharide (MOS)

• fructooligosaccharide (FOS)

• galactooligosaccharide (GOS)

• xylooligosaccharide (XOS)

• isomaltooligosaccharide (IMOS)

• soybean oligosaccharides (SOS)

• pectic oligosaccharides

• chitooligosaccharide

• lactusucrose and lactulose

• inulin, resistant starch, and arabinogalactins

the effects of prebiotics remain inconclusive

• studies in vitro and some in vivo suggest hat prebiotics may increase the growth of some bacterial species (lactobacilli)

• canine and feline studies are scarce and generally show safety rather than health improvement

• further studies are needed and their use in companion animal diets are largely marketing claims

probiotics are live organisms used to alter microflora

• probiotics are live or viable bacterial cell mixtures that have beneficial effects on the health

• probiotics should be nonpathogenic and resist stomach acid and bile

• probiotics provide health benefits by adhering to intestinal epithelial tissue and colonizing the intestinal tract

• adherence is more important than colonization

prebiotics and probiotics could be used simultaneously

• mixtures of prebiotics and probiotics are sometimes used

• ideally, the probiotic ferments the prebiotic

• the mixtures are called synbiotics

• although the effect is expected to be synergistic, studies failed so far to show such an effect