Effect of coconut oil and tricaprylin vs. triolein on survival, growth and fatty acid composition of common carp ( Cyprinus carpio L.) larvae

Abstract

A 21-day feeding trial was carried out to investigate the ability of first-feeding carp larvae to utilize medium-chain fatty acids (MCFA). Six semi-purified diets, with a common casein and soluble fish protein concentrate basis, were tested on triplicate groups of 400 larvae. The diets were isolipidic (23–24% of dry matter). They differed only by triacylglycerol supplementation (10% of diet) which consisted of either triolein (TO), coconut oil (CO) or tricaprylin (TC) alone or in combination of two of these (TO+CO, CO+TC, TO+TC). Survival and growth rates of larvae fed with CO or TO were high (survival 95–97%, mean wet weight 60–67 mg after 21 days). Addition of TC (5 or 10% of diet) induced a significant mortality as early as 11 days of feeding and resulted in a final survival of less than 6%. TC also led to reduced growth rates (final mean larval weight 6–13 mg). The fatty acid (FA) composition of larvae fed with TO or CO reflected that of the diets with high levels of oleic acid (42% of total FA) in larvae fed with TO and lauric and myristic acids (17 and 10% of total FA, respectively) in larvae fed with CO. In contrast, larvae fed with TC contained only traces (0.3% of total FA) of caprylic acid but had higher levels of capric acid than other larvae (6% vs. 1–2%). Present results indicate an important difference in the utilization between MCFA supplied as CO (12:0) and TC (8:0).