Lipid metabolism in laying hens

1.Digestion of lipids

Fat digestion takes place primarily in the small intestine. The process can be simply summarized as: lipid hydrolysis – the hydrolyzed products form soluble particles – the small intestinal mucosa takes up these particles – re-synthesizes triglycerides in the small intestinal mucosal cells – and the triglycerides enter the blood circulation.

2.Absorption of lipids

* Mixed particles formed in the duodenum carry digestive products of lipids to the mucosal cells of the small intestine for absorption.

* When the mixed chylomicron comes into contact with the villi membrane, it breaks, and the released lipid hydrolysates are mainly absorbed in the duodenum and upper jejunum. Bile salts are also released.

* Lipid hydrolysates are absorbed through the facilitated diffusion process.

* Jejunum is the main part of pig and poultry to absorb and digest lipids.

3.Metabolism of lipid in laying hens

* Lipid source: feed absorption, de novo synthesis

* Lipid synthesis site: liver

* Where fats go: They are transported out of the liver by lipoproteins and into the egg yolk and other tissues.

* Triglycerides cannot be transported out of the liver in time, resulting in hepatic steatosis, which over time develops into fatty liver disease.

* Fatty liver is the main health problem facing laying hens in the late laying period, which will cause greater economic losses.

Polyunsaturated fatty acid function eggs

1.Infant and maternal PUFA egg development: the higher the DHA, the better

DHA,(Docosahexaenoic Acid), commonly known as brain gold, scientific name: Docosahexaenoic Acid, a long-chain polyunsaturated fatty acid composed of 22 carbon atoms and 6 double bonds, is an important member of the omega-3 family. A large number of studies have shown that DHA is a major nutrient for the growth and maintenance of nervous system cells, and an important component of brain, nerve tissue and retina. In recent years, DHA(Brain Gold) has become a major focus of maternal and child nutrition.

2.Infant and maternal PUFA egg development: the lower the EPA, the better

EPA (Eicosa-pentaenoicacid), eicosapentaenoic acid, like DHA, is an important part of the brain and nervous system.

However, studies have found that EPA may be related to early puberty in children, and FAO recommends that the ratio of EPA/DHA in infants’ diets should not exceed 1:4. Deep-sea fish oil (usually tuna oil) is rich in DHA, but also contains EPA, with an EPA/DHA ratio of about 1:1 to 2:1.

Seaweed oil or seaweed powder is rich in DHA and does not contain EPA, but contains lauric acid, soy acid and other ingredients that are not good for infants and young children

Conclusion

It is feasible to regulate lipid metabolism of laying hens, lipid content in eggs and the production of polyunsaturated fatty acid functional eggs by means of nutritional regulation, which should be studied according to different needs.