Effects of Different Feeding Regimes on Growth Performance, Survival Rate, Carcass Composition, Fatty Acids Profile, and Digestive Enzyme Activities of Great Sturgeon (Huso huso Linnaeus, 1758) Larvae

Abstract

Six different feeding regimes (FR) were tested from 7 to 38 days post hatching (dph). Five thousand four hundred larvae (7 dph, 0.048 g) were randomly stocked in 18 fiberglass tanks contained 100 L fresh water (300 larvae per each tank). In larvae fed with FR-B, includes Artemia nauplii (AN) + Artemia biomass (AB) + microdiet (MD), the body weight (BW) at the end of trail (38 dph) similar the FR-D (AN + CHL + AB + MD), and E (AN + CHL + AB), was at high level. Survival rate was higher in larvae fed FR-A includes AN + chironomid larvae (CHL) + MD, but had a lower BW ( $p<0.05$ ). Moderate BW and survival rate were detected in larvae fed FR-C (AN + DP + MD). Larvae fed only MD (FR-F), had the lowest survival and the highest BW ( $p<0.05$ ). Different FR had a significant effect on crude protein (CP), crude fat (CF), ash, and dry weight ( $p<0.05$ ). The larvae fed FR-C and D had the highest CP ( $p<0.05$ ). The highest CF and ash in larvae were detected in FR-F and C, respectively ( $p<0.05$ ). Larvae from FR-A and B had higher levels of n−3 long chain polyunsaturated fatty acids in comparison with others FR ( $p<0.05$ ). The use of AB and CHL can increased the weight and survival rate of larvae, respectively. At the end of trail, the activity of pepsin, trypsin, lipase and α-amylase enzyme levels were lower in FR-B and F than others FR. Totally, by using a combination of AN + CHL + AB + MD had better results than others and ordered to H. huso larvae feeding. Using MD alone, can cause lesser development of the digestive system and little attractiveness, therefore it can cause starvation, and the empty digestive tract of larvae.