POULTRY DAIRY FEED FORMULATION -1

Digestion of Lipids in Poultry: Limitations and Opportunities

Steps in lipid digestion

Lipid absorption

Factors influencing the digestion and absorption of lipids

Opportunities to improve fat utilisation

Use of fat and oil in poultry diets

Increase the caloric density of ration

Control dustiness and increase palatability

Reduces wear on mixing equipments

Carrier of fat soluble vitamins and pigments

Prevent particle separation

CCK

Nutrients in duodenum

Contraction of gall bladder

Regulation of bile flow

Regulation of pancreatic secretion

Bile

Bile salts

Phospholipids

Emulsification - by reducing the tension at the oil-water surface

Activates and also prevents denaturation of lipase

Co-lipase

Has no enzyme activity

Induces lipase activity

Lipase

Position 1

Position 3

Position 2 fatty acid remains as a monoglyceride

Emulsification – starts in gizzard- Accelerated by bile salts

Contact with lipase and co-lipase

Break down to monglyceride and fatty acids

Emulsified by conjugated bile salts

Mixed micelle formation

Attach to epithelial cell

Formation of micelles and provision of high concentration of fatty acids next to epithelial cells

Passive absorption - depends on fatty acid binding protein (FABP) – low affinity to SFA

MG and free fatty acids are re-esterified, and combined with cholesterol, lipoprotein and phospholipids (portomicrons)

Transported via systemic circulation (liver or tissues) and, metabolised as a source of energy or stored

Effect of rate of feed passage

Rapid transit time - limited time for digestion

Bile status

Amount of bile salts

Inefficient entrohepatic re-circulation

Lower replacement of bile salts lost by excretion

FABP

Lower FABP

Digestive enzyme status

Lipase secretion and/or activity

Fat digestion and absorption

Fat quality

Fat inclusion level

Dietary Ca level

Saturation and chain length

Fatty acid position on triglyceride

Cereal base