SPECIAL STORY FEED & ADDITIVE MAGAZINE March 2023 61 Choline Cholic acid is a naturally occurring, primary bile acid that represents a major component of the total bile acid pool in humans. Cholic acid is synthesized from cholesterol in the liver and it is conjugated to either with glycine (glycocholic acid) or taurine (taurocholic acid) before the secretion in the bile. Choline is considered as a lipotropic factor preventing excessive lipid accumulation and development of fatty livers. Several studies reported that fish fed the diets containing supplemental choline had significantly lowered the total lipid in liver compared with the fish fed diets without supplemental choline, and total lipid in muscle significantly increased by supplemental choline. Furthermore, studies have investigated the effects of dietary choline level on lipid deposition in fish, the underlying molecular mechanisms remained unknown (Li et al., 2014). Reduced hepatic lipid contents in fish fed increasing dietary choline levels have been reported in a study conducted by (Griffin et al., 1994). CONCLUSION Fats and oils constitute the main energy source of animals and possess the highest caloric value of all nutrients, with almost 3 times higher apparent metabolizable energy. Hence, fats are widely added to animal diets to meet energy requirements. However, their digestion, and absorption, are poorly developed in young animals and ultimately provide lower available energy to fish. Hence the addition of an emulsifier in feed could enhance lipid digestibility and thereby protein sparing effect can reduce the cost of costly protein in the feedstuff so further investigation of emulsifiers as feed additives is required. References 1. Jauncey, K. (1998). Tilapia feeds and feeding. 2. National Research Council. (1993). Nutrient requirements of fish. National Academies Press 3. Shiau, S. Y., & Lin, S. F. (1993). Effect of supplemental dietary chromium and vanadium on the utilization of different carbohydrates in tilapia, Oreochromis niloticus× O. aureus. Aquaculture, 110(3-4), 321-330. 4. Lu, K. L., Xu, W. N., Li, X. F., Liu, W. B., Wang, L. N., & Zhang, C. N. (2013). Hepatic triacylglycerol secretion, lipid transport and tissue lipid uptake in blunt snout bream (Megalobrama amblycephala) fed high-fat diet. Aquaculture, 408, 160-168. 5. Bolla, S., Nicolaisen, O., & Amin, A. (2011). Liver alterations induced by long-term feeding on commercial diets in Atlantic halibut (Hippoglossus hippoglossus L.) females. Histological and biochemical aspects. Aquaculture, 312(1-4), 117-125. 6. Lu, K. L., Xu, W. N., Liu, W. B., Wang, L. N., Zhang, C. N., & Li, X. F. (2014). Association of mitochondrial dysfunction with oxidative stress and immune suppression in blunt snout bream Megalobrama amblycephala fed a high-fat diet. Journal of aquatic animal health, 26(2), 100-112. 7. Hofmann, A. F., Hagey, L. R., & Krasowski, M. D. (2010). Bile salts of vertebrates: structural variation and possible evolutionary significance [S]. Journal of lipid research, 51(2), 226-246. 8. Wang, C. S., & Hartsuck, J. A. (1993). Bile salt-activated lipase. A multiple function lipolytic enzyme. Biochimica et Biophysica Acta (BBA)-Lipids and Lipid Metabolism, 1166(1), 1-19. 9. Craig, S. R., & Gatlin III, D. M. (1997). Growth and body composition of juvenile red drum (Sciaenops ocellatus) fed diets containing lecithin and supplemental choline. Aquaculture, 151(1-4), 259-267. 10. Koven, W. M., Tandler, A., Sklan, D., & Kissil, G. W. (1993). The association of eicosapentaenoic and docosahexaenoic acids in the main phospholipids of different-age Sparus aurata larvae with growth. Aquaculture, 116(1), 71-82. 11. Kanazawa, A. (1993). Nutritional mechanisms involved in the occurrence of abnormal pigmentation in hatchery‐reared flatfish. Journal of the World Aquaculture Society, 24(2), 162-166. 12. Li, J. Y., Zhang, D. D., Xu, W. N., Jiang, G. Z., Zhang, C. N., Li, X. F., & Liu, W. B. (2014). Effects of dietary choline supplementation on growth performance and hepatic lipid transport in blunt snout bream (Megalobrama amblycephala) fed high-fat diets. Aquaculture, 434, 340-347. 13. Griffin, M. E., Wilson, K. A., White, M. R., & Brown, P. B. (1994). Dietary choline requirement of juvenile hybrid striped bass. The Journal of nutrition, 124(9), 1685-1689.
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