S. Fontagne, T. Pruszynski, G. Corraze and P. Bergot
A 21-day feeding trial was carried out in order to investigate the ability of first-feeding carp larvae to utilize medium-chain triglycerides (MCT). Six semi-purified diets based on casein and soluble fish protein concentrate were fed to triplicate groups of 400 larvae. The diets were isolipidic and different only by the added triglyceride source (10% of diet) which was composed of triolein (OL) or coconut oil (CO) or tricaprylin (CA) or a combination of two sources in equal part.
Survival and growth rates of larvae fed CO or OL-diets were not significantly different (survival 96-97%, mean weight 60-67 mg after 21 days). Addition of CA (5 or 10% of diet) induced a significant mortality even by 11 days of feeding and resulted in a final survival less than 7%. Further growth was also reduced in this group (final mean larval weight 5.5-13.2 mg). The fatty acid composition of larvae reflected that of the diets with high amounts of oleic acid (42% of total fatty acids of larvae reflected that of the diets with high amounts of oleic acid (42% of total fatty acids of larvae fed OL-diet) or lauric and myristic acids (17 and 10% respectively of total fatty acids of larvae fed CO-diet).
In contrast, larvae fed CA-diets did not contain caprylic acid but had higher amounts of capric acid than other larvae (6% vs. 1-2%)
Present results indicate important differences in the utilization of MCT provided by coconut oil and tricaprylin.
(Unite Mixte INRA-IFREMER de Nutrition des Poissons, Station d'Hydrobiologie, BP 3, 64310 Saint-Pee-sur-Nivelle, France)