Replacement of cholesterol in feed for white shrimp

By Alexander van Halteren, Sam Ceulemans, and Peter Coutteau, Nutriad International NV, Dendermonde, Belgium.

Bile salts are natural emulsifiers capable of enhancing the digestive capacity for lipids in the digestive system of shrimp by improving the lipid emulsification and micelle formation, resulting in a faster absorption of lipids in the hepatopancreas. Furthermore, bile salts constitute an alternative source for the steroid ring that shrimp cannot synthesize, which is at the basis of their requirement for dietary cholesterol. Bile salts have a species‐specific composition and molecular structure. The commercial availability of bile salts is mostly restricted to pharmaceutical grade applications of purified cholic acid from bovine origin, extracted from healthy animals from BSE free countries, due to its elevated cost, not applicable in animal feeds. They need to comply with EU regulations on maximum threshold levels on undesirable substances (e.g. heavy metals, PCB’s, dioxine, pesticide residues, antibiotic residues).

Although the use of bile salts in shrimp nutrition has been empirically documented, it is not known to what extent the efficacy of bile salts is affected by its origin, composition and/or molecular structure.

Shrimp are incapable to biosynthesize n‐ 3 highly unsaturated fatty acids (HUFA) and cholesterol, and have a limited
capacity to produce phospholipids de novo. Therefore, these essential lipids need to be supplied through the feed for optimizing growth and health of farmed shrimp. The increased cost and/or limited availability of essential fat sources for shrimp feed, particularly fish oil, cholesterol and/or lecithin, have become a challenge for shrimp nutritionists during recent years.