فهرست مطالب انریک گیسبرت

The purpose of this study was to survey the effect of dietary fish oil replacement with different levels of soybean lecithin on growth performance and digestive enzymes activity of Persian sturgeon. Three hundred and sixty fish with average weight of 85 ± 0.09 g were treated with 6 experimental diets and three replicates, containing 0, 2, 4, 6, 8 and 10 percent soybean lecithin for 10 weeks. Based on the biometry at the end of culture period, the highest weight gain, final weight, length and specific growth rate were present in the 6% dietary fish oil replacement with soybean lecithin treatment, which showed significant difference with other treatments (P≤0.05). There was no significant difference in condition factor between different treatments. The lowest FCR value was observed in treatment 4 which showed a significant difference with other treatments (P≤0.05). Digestive enzymes activity such as lipase, pepsin, chymotrypsin, and amylase did not show any significant differences between different treatments, however trypsin exhibited significantly higher activity in treatment 4 ( 6%lecithin) compared to fish treated diets with 0% (control) and 2% fish oil replacement with lecithin (P≤0/.05). It can be concluded that replacement of fish oil up to 6% with soybean lecithin in A. persicus diet improves weight gain, final weight, specific growth rate, food conversion rate and trypsin activity significantly.

Bone gla protein and matrix gla protein are of common origin with evolutionary relation and have similar structural features and are functional in the formation of skeletal structures The present study have been evaluated the genes encoding vitamin k-dependant proteins (VKDPs) expression at hatching time (0), 1, 3, 6, 10, 12,14, 20, 30 and 50 in skeletal Persian sturgeon sturgeon (Acipenser persicus Bordin, 1897). The results of quantitative real-time PCR showed that the transcripts of VKDPs genes including bone Gla protein (bgp) and  matrix Gla protein (mgp ) were significantly up-regulated during the transition to the exogenous feeding, confirming the hypothesis about the relevance of the above-mentioned genes in chondrogenesis at early developmental stages. Maximal levels of bgp and mgp expression at juvenile stage, indicating the importance of these genes in the mineralization of the skeleton in sturgeons, although these genes are also expressed in other body tissues. This information can be considered as a reference for other studies evaluating the quality of larvae and the influence of rearing biotic and abiotic factors in the skeletogenesis of this sturgeon species and the occurrence of skeletal deformities.

Lecithin as a source of phospholipid are considered to increase the growth efficiency, reproduction and evolution of fish and crustaceans. Due to Insufficient synthesis of phospholipids in the aquatic this research was performed to investigate the effect of enrichment of Artemia franciscana nauplii and adults with soybean lecithin on proximate and lipid class composition. In the first stage, 200,000 nauplii / liter of water was enriched with soyabeen lecithin (74.42% phospholipid) for 24 hours. Enrichment emulsion (with a ratio of 10:1 ml: g of water and powdered lecithin) was added to enrichment containers at 3 ml for 2 times zero (beginning of enrichment) and 12 hours. To enrich adult Artemia (14 days and length 8.50 mm) with a density of 3000 Artemia per liter similar the first step the enrichment emulsion at 3 ml was used at 0 and 3 hours. After 6 hours, the enriched Artemia was washed by sieve and harvested. The results showed that there was no significant difference in the amount of dry matter and crude protein between lecithin-enriched Artemia nauplii and adults and unenriched Artemia (P> 0.05). Enrichment with lecithin in both steps of nauplii and adults, causes a significant increase in the amount of crude lipid (in nauplii from 17.62 to 21.39 and in biomass from 16.05 to 19.69 %). In terms of lipid classes, phosphatidylcholine, phosphatidylserine + phosphatidylinositol was significantly higher in lecithin-enrichednauplii than unenriched nauplii (P< 0.05). In enriched Artemia adult, levels of phosphatidylethanolamine and lysophosphatidylcholine were significantly different than control groups. Also enrichment of Artemia nauplii and adults with soybean lecithin significantly increased total polar lipids (12.96% and 43.72%) and triglycerides (53.35% and 79.9%). In conclusion, it can be stated that using 0.6 g L-1 soybean lecithin increases phospholipid groups as well as total fat in Artemia nauplii and adults.

In the present study, the process of the skull development and calcification in Persian sturgeon (Acipenser persicus) was studied. Development of cartilage started after hatching around the head and notochord (10.6 mm, total length, TL) and the first calcification process occurred in dermopalatine and dentary bone jaw coincident with mixing feeding. The appearance of dermal skeletal on the body divided into three stages: (a) the yolk-sac (comprised of hatching to the late larval stage (12 DPH, 16 mm TL) in which no calcified structures became visible and the cartilaginous elements of skull with feeding and breathing roles have appeared. (b) the larval stage (between 16 and 20.25 mm, 23 DPH) in which, the first calcification process related to feeding and breathing occurred and weak mineralized dermal bones such as subopercle and supracleithrum developed; and (c) the metamorphosis stage between 27.25 and 83.3 mm TL) during which the formation of mineralized dermal bones occurred between 32 and 50 days post-hatching, and teeth were disappeared on dentary and dermopalatine bones. The results of this study could be useful for decreasing the larval mortality and improving the stock conservation programme of Persian sturgeon.