Sturgeons are one of the most popular and valuable marketable fish species in the world in terms of their caviar and meat. The sturgeon species owing to indiscriminate fishing, water pollution, destroy of spawning places, and construction of dams, are listed as endangered fish by International Union for Conservation of Nature (IUCN, 2018). Today, sturgeon farming has been expanded rapidly in the world. Among the aquaculture of sturgeons, great sturgeon, Huso huso, has made a promising candidate because of high growth, resistance to stress factors and reception of formulated diets (Matani Bour et al.,
Background: Sea foods contain high level of unsaturated fatty acids. The aim of this study is comparison of ώ 3 and ώ 6 levels in wild and farmed green tiger shrimp (P.semisulcatus). Materials and Methods: in this study 120 shrimps (wild=60 and farmed=60) selected. Analysis of Fatty acids was performed by Gas Chromatography. Two-factor variance difference analysis used for demonstration the effects of main factor (sex and environment) and their interactions. Results: Three fatty acids included linoleic, Decosahexaenoic (DHA) and eicosapentaenoic (EPA) were the most dominant fatty acids in the wild and farmed species. Among ώ 6 fatty acids, the farmed shrimp contained a higher level of linoleic acids (P>0.05) whereas in ώ 3 fatty acids, eicosapentaenoic acid (EPA) and eicosathereanoic acid were significantly higher in wild shrimps. The n-3/n-6 fatty acids ratio was similar in two groups. The comparison of DHA/EPA ratio did not show difference between wild and farmed shrimps and this ratio was affected by sex. Conclusion: Comparison between two groups showed that the concentration of fatty acids is relatively to each other in wild and farmed shrimp.
Thiamine is a crucial nutrient in larval stage of fish, and thus, the present study aimed at evaluating the effects of dietary thiamine supplementation on survival, growth performance, and biochemical parameters of beluga, Huso huso, larvae. The fish larvae (50 ± 4.5 mg) were fed diets containing 0 (control), 5, 10, and 20 mg/kg thiamine for 26 days from 18 days after hatching to 44 days after hatching. Thiamine significantly increased the larvae survival, growth rate, digestive enzymes activity, and whole body protein and ash but decreased the whole body lipid and moisture
P
<
0.001
). Also, alanine amino transferase (ALT) and alkaline phosphatase (ALP) were decreased significantly in thiamine-treated groups (
P
<
0.05
). The highest survival and whole body ash were observed in 20 mg/kg thiamine treatment; the highest whole body protein and lipase activity were observed in 10 mg/kg thiamine treatment. The highest growth rate, amylase, and lowest whole body lipid, alanine amino transferase (ALT), and alkaline phosphatase (ALP) were observed in 10 and 20 mg/kg thiamine treatments. All thiamine-treated fish exhibited similar pepsin and chymotrypsin activities, all above the control fish. There were no significant effects of dietary thiamine supplementation on trypsin, whole body lysozyme, alternative complement (ACH50), lactate dehydrogenase (LDH) activities, and IgM levels. According to the results, 10–20 mg/kg dietary thiamine supplementation can increase the performance of beluga larvae by improving the health of liver and the activity of digestive system.
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.
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