Title: The effect of enrichment on the fatty acid composition of Artemia salina
Abstract
The initial feeding of small fish larvae is problematic and knowledge of their nutritional requirement is often scarce or lacking. The larvae are small and undeveloped and it is difficult to process nutritionally sound and complete dry micro-feed which is stable in water. Therefore, life feed like rotifers and Artemia are still essential part in marine finfish hatcheries. Standard methods have been developed for hatching and enhance the nutritional value of life feed using different enrichment product. There are various available enrichment products in the market but often a lack of knowledge how well they might fit in for a particular fish larva species. The first step is to recognize how well the life feed is absorbing and preserving nutrients from different enrichment product. Artemia salina was enriched with four enrichment diets including Nanochloropsis, Isochrysis, Pavlova and Cod liver oil for 12h and 24h. Survival, energy content and fatty acid composition of Artemia was determined after 12h and 24h enrichment. Survival of Artemia was highest in cod liver oil (95%), followed by Nanochloropsis, Isochrysis and Pavlova. However, there was not significantly different (p > 0.05) in survival rate among the enrichment feeds for both two enrichment time, except for 24h enriched Artemia with Pavlova (66%). The energy content of both cyst and newly hatched Artemia was not significantly different (15 kJ/g, p > 0.05). No significant differences (p > 0.05) in energy content among cyst, newly-hatched Artemia and 12h enriched Artemia with all feeds were detected. With 24h enrichment treatment, difference in energy contents of Artemia fed Nanochloropsis, Isochrysis, Pavlova and cod liver oil was detected (p < 0.05). The higher energy content was found with cod liver oil treatment (19 kJ) compared with the other feeds treatments (from 7.7 kJ to 11.6 kJ). The energy content of Artemia enriched with all feeds was not influenced by enrichment time. The results of survival and energy content of Artemia in this study indicate that all four enrichment feeds can be used successfully in the rearing of Artemia for short term feeding. With fatty acid composition, the results in this study did not allow a clear conclusion for the effect of enrichment on fatty acid composition of Artemia because of high un-identified fatty acid compositions.