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
CCK
Bile
Co-lipase
Lipase
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
Bile status
FABP
Digestive enzyme status
Fat digestion and absorption