Carbohydrate Digestion and Absorption in Monogastrics and Ruminants - Prof. Jeffrey T. Tra, Study notes of Community Health

Download Carbohydrate Digestion and Absorption in Monogastrics and Ruminants - Prof. Jeffrey T. Tra and more Study notes Community Health in PDF only on Docsity!

Carbohydrate Digestion

Digestion and

Absorption

Non-ruminant Ruminant

CHO in feed digestive enzymes Glucose in small intestine Absorption into blood circulation microbial fermentation Volatile fatty acids in rumen

Non-Ruminant

Carbohydrate Digestion



Mouth

 Salivary amylase  (^) Breaks starches down to maltose  (^) Plays only a small role in breakdown because of the short time food is in the mouth  (^) Ruminants do not have this enzyme  (^) Not all monogastrics secrete it in saliva

Carbohydrate Digestion



Pancreas

 (^) Pancreatic amylase  (^) Hydrolyzes alpha 1-4 linkages  (^) Produces monosaccharides, disaccharides, and polysaccharides  (^) Major importance in hydrolyzing starch and glycogen to maltose Polysaccharides (^) Disaccharides Amylase

Digestion in Small

Intestine

Maltose Glucose + Glucose Maltase Lactose Lactase Glucose + Galactose

• Poultry do not have lactase Sucrose Glucose + Fructose Sucras e
• Ruminants do not have sucrase

Digestion of Disaccharides



Newborns have a

full complement

of brush-border

enzymes

Miller et al. (eds.), 1991

Digestion in Large

Intestine



Post-gastric fermenters (horse and

rabbit)

 (^) Can utilize large quantities of cellulose  (^) Cecum and colon contain bacteria which produce cellulase  (^) Cellulase is capable of hydrolyzing the glucose-4-beta-glucoside linkage

Overview Monogastric Carbohydrate Digestion Location Enzymes Form of Dietary CHO Mouth Salivary Amylase Starch Maltose Sucrose Lactose Stomach (amylase from saliva) Dextrin → Maltose Small Intestine Pancreatic Amylase Maltose Brush Border Enzymes Glucose Fructose Galactose

Glucose Glucose Glucose Large Intestine None Bacterial Microflora Ferment Cellulose

Carbohydrates Monosaccharides Small Intestine Active Transpor t Liver Portal Vein Distributed to tissue through circulation

Nutrient Absorption - Carbohydrate 

Active transport for glucose and

galactose

 Sodium-glucose transporter 1 (SGLT1)  Dependent on Na/K ATPase pump 

Facilitated transport for fructose

Summary of Carbohydrate

Digestion and Absorption in

Monogastrics

 Consist of starches, glycogen, sucrose, lactose, glucose, fructose  Polysaccharides broken down to monosaccharides  Monosaccharides taken up by active transport or facilitated diffusion and carried to liver  Glucose is transported to cells requiring energy  Insulin influences rate of transport

Carbohydrate Digestion

in Ruminants



Ingested carbohydrates are exposed

to extensive pregastric fermentation



Rumen fermentation is highly

efficient considering the feedstuffs

ingested

 (^) Most carbohydrates fermented by microbes before they can be exposed to typical gastric and small intestinal enzymes

Microbial Populations



Cellulolytic bacteria (fiber

 digesters)

Produce cellulase - cleaves β 1 →4 linkages  (^) Prefer pH 6-  (^) Utilize N in form of NH 3  (^) Require S for synthesis of sulfur-containing amino acids (cysteine and methionine)  (^) Produce acetate, propionate, little butyrate, CO 2  (^) Predominate in animals fed roughage diets

Microbial Populations



Amylolytic bacteria (starch, sugar

digesters)

 (^) Digest starch  (^) Prefer pH 5-  (^) Utilize N as NH 3 or peptides  (^) Produce propionate, butyrate and sometimes lactate  (^) Predominate in animals fed grain diets  (^) Rapid change to grain diet causes lactic acidosis (rapidly decreases pH)  (^) Streptococcus bovis