Comparative Aspects of Comparative Aspects of Carbohydrate Digestion in Carbohydrate Digestion in

Cattle and HorseCattle and Horse

Zaman FarahiZaman Farahi

Individual project Individual project Comparative NutritionComparative Nutrition

CarbohydrateCarbohydrate DefinitionDefinition As a brief definition carbohydrate is a As a brief definition carbohydrate is a

chemical compound includes hydrogen chemical compound includes hydrogen (H), carbon (C), and oxygen (O) with (H), carbon (C), and oxygen (O) with (CH2O)n as a general formula where (CH2O)n as a general formula where nn varies between 3 or more varies between 3 or more

Non structural carbohydrate Non structural carbohydrate (NSC)(NSC)

storage form of carbohydratestorage form of carbohydrate main sources of energy for main sources of energy for

ruminant and non ruminant ruminant and non ruminant animals animals

suchsuch as sugars, starch, and organic acid as sugars, starch, and organic acid

StarchStarch I.I. Amylose (20-30%)Amylose (20-30%)II.II. Amylopectin (70-80%)Amylopectin (70-80%)

Structural carbohydrateStructural carbohydrate v cell wall fraction of the plantcell wall fraction of the plant q cellulosescellulosesq hemicelluloseshemicellulosesa.a. Resistant to enzymes digestionResistant to enzymes digestionb.b. Must be fermented by Must be fermented by

microorganismsmicroorganisms

Structural and nonstructural carbohydrates of plant

Plant carbohydrates

Cell content Cell wall

Hemicellulose

Cellulose

Organic acid

Sugars

Starches

Fructans

Pectin, βglucan, Galactan

ADF

NDFNeutral detergent

soluble fiber

Neutral detergent soluble CHO

Grasses carbohydrates

Proximate compositions Constituent 2 weeks 6 weeks 10 weeks

Glucose 16 Fiber 20.45 21.62 25.33

Fructose 13 Ether extract 3.75 2.42 2,1

Sucrose 45 Crude protein 18.45 12.12 6.90

Fructans 70 True protein 13.32 7.80 5.47

Galactan 9        

Araban 29        

Xylan 63        

Cellulose 202        

(Other) Lignin 52        

Mc donald et al., 2002Watson. 2007

Carbohydrate sources

LegumesLegumes Red clover, white clover, Red clover, white clover, Lucerne Lucerne

((Alfalfa)Alfalfa) grown in tropical regions with high temperaturegrown in tropical regions with high temperature Higher protein and mineral and also less nutritional Higher protein and mineral and also less nutritional

variability with age than grassesvariability with age than grasses sugars such as sucrose in clover have similar proportion sugars such as sucrose in clover have similar proportion

to grassesto grasses Compared to the legumes, the grass forages contained Compared to the legumes, the grass forages contained

substantially larger amounts of the cell wall contentsubstantially larger amounts of the cell wall content More-rapidly digestible and higher intakes than grasses More-rapidly digestible and higher intakes than grasses

Cereal grainsCereal grains Barley, maize, oats, and wheat Barley, maize, oats, and wheat high energy and protein content high energy and protein content composition of grains is less variable than forages composition of grains is less variable than forages

but dissimilarity in the nutrient compositions of but dissimilarity in the nutrient compositions of grains are changeable depending on soil fertility grains are changeable depending on soil fertility and growth situationand growth situation

main constituent of the concentrate main constituent of the concentrate ration ration

Carbohydrate composition in different feedstuff

Feedstuff NDF% NFC% NSC%Alfalfa hay 43.1 22.0 12.5Beet pulp 47.3 36.2 19.5Corn gluten meal 7.0 17.3 12.0Mixed mostly grass hay 60.9 16.6 13.6Soybean meal 9.6 34.4 17.2Soy hulls 66.6 14.1 5.3

Lawrence et al 2007

Digestive tract

Digestive process Mechanical Chemical Microbial

Degradability of carbohydrates Fraction A: Fast degradability such as

sugars Fraction B1: Intermediate

degradability such as starch Fraction B2, which has slow

degradability such as celluloses and hemicelluloses

Fraction C: unavailable cell wall (lignin)

Discussion

Carbohydrate digestion in mouth

Stomach Small volume Small portions of feed Limited enzymatic

digestion Partial fermentative

activities Small microbial population Highly fibrous feeds, such

a poor quality hay or chaff, are passed more quickly through the stomach as compared to denser grains

Stomach cont. four compartments High microbial

fermentation Rumination Microorganisms

such as Bactria, protozoa, fungi, and yeasts

Carbohydrate digestionCellulose Starch

Cellobiose Isomaltose

Fructose Fructan

Sucrose

Glucose

Maltose

Pentoses

Uronic acids

Hemicelluloses

Pentosanns

Pectin

Glucose-1-phosphate

Fructose-1, 6-phosphate

Fructose-6-phosphate

Glucose-6-phosphate

Pyruvate

Mc donald et al, 2002

Carbohydrate digestion Cont.

Acetyl CoALactate

Malate

Fumarate

Succinate

Propionate Acetate Butyrate

Acrylate

Methane

Oxaloacetic acid

pyruvate

Aceto-acetyl CoA

Formate

Cheeke and dierenfield, 2010

Small intestine The rate and extent of starch digestion is

determined by:1. Properties of the starch granule2. The effect of processing3. Associated food structures (plant cell walls)4. Transit time through the small intestine5. The availability and concentration of enzymes Resistant starch, together with undigested starch, will pass into the large intestine of the

horse where it may be fermented to short chain fatty acids

starch in large intestine

starch

Bacterial digestion

Lactic acid production

PH reduction

Loss of bacteria and toxin production by bacteria

Colic disorder

Small intestine cont…. Digestible dietary carbohydrates

are hydrolyzed in the intestinal lumen, to the monosaccharides by several intestinal enzymes such as pancreatic Alfa-amylase and brush-border membrane disaccharides, sucrase, maltase and lactase

Small intestine cont…. The small intestine function in cattle is like

that of the other mammalian Digesta that departs the rumen and enters

the small intestine contains some microbes and undigested fiber, as well as protein and some sugars produced by the microbes

Similar to horses, the process of intestinal starch digestion in cattle starts in the lumen of the small intestine with the secretion and action of pancreatic Alfa-amylase

Large intestineLarge intestine• Main site of microbial Main site of microbial

fermentationfermentation

• As in the rumen, the As in the rumen, the major productions of major productions of fermentation process fermentation process consists of short-chain or consists of short-chain or volatile fatty acids in volatile fatty acids in particular particular acetic, acetic, propionic, and butyric, propionic, and butyric, lactate and succinate, lactate and succinate, and various gases (CO2, and various gases (CO2, H2, CH4)H2, CH4)

Large intestine cont…Large intestine cont…• The proportion of The proportion of

fiber digestibility in fiber digestibility in horses is normally horses is normally lower than in lower than in ruminants due to ruminants due to higher passage rate higher passage rate and less proper and less proper environment? for environment? for microbial growthmicrobial growth

Large intestine cont….Large intestine cont….• The hindgut of ruminant has microbial The hindgut of ruminant has microbial

activity such as that of the rumenactivity such as that of the rumen• Microbial activities take place by enzymes Microbial activities take place by enzymes

produced by different microorganisms produced by different microorganisms (cellulase) (cellulase)

• The caecum has little function in a The caecum has little function in a ruminant, unlike its role in horses ruminant, unlike its role in horses

• The colon is the site of most of the water The colon is the site of most of the water absorption in the large intestine absorption in the large intestine

Conclusion • Energy requirements of animal should be met

from carbohydrates • The main differences between GI tract of cattle

and horse refer to the volume of rumen and large intestine

• Fiber contents mostly can not be digested by enzymic digestion

• Cell wall contents and some starch contents must be fermentd in the rumen and large intestine for cattle and horse respectively.

• Microbial fermentation is more efficient in cattle than that of the horse

• Utilization high amount of carbohydrate sources leads to a number of disorders in animals.

Thanks for attentionThanks for attention