Comparative study of the effects of HUFA in dry diets and natural foods on fecundity and egg diameter of female broodstock of white leg shrimp (Litopenaeus vannamei)

During 2 months (from April to June, 2008) we studied the suitable quantity of Highly Unsaturated Fatty Acids (HUFA) for desirable fecundity and egg diameter of female broodstock of white leg shrimp (Litopenaeus vannamei). Similar dry food containing Isonitrogeneous material (31.5% protein) and Isolipid (6.9% lipid) was used but with different levels of HUFA (1, 2 and 3%). Also, the HUFA of natural foods (Perinereis worm, melalis bivalvia and cuttlefish) was analyzed. We compared the effects of four levels of dietary HUFA (1, 2 & 3 % HUFA of dry diets and the average HUFA of natural diets) on fecundity and egg diameter of female broodstock of white leg shrimp. The fecundity and egg diameter of natural diet and HUFA 3% were not significantly different (P>0.05). The fecundity of natural diet and HUFA 3% was significantly higher than the other two treatments (P<0.05) and also the egg diameter of HUFA 3% and natural diet was significantly higher than the other two treatments (P<0.05). According to the results of fecundity and egg diameter measurements, both natural and HUFA 3% diets are suggested as suitable for white leg shrimp breeding

Fluctuation of gonadosomatic index during oocyte development in the narrow-clawed crayfish Astacus leptodactylus (Eschscholtz, 1823) in Aras Dam Lake, Iran

This study was carried out with the aim of examining the seasonal reproductive cycle of the female crayfish Astacus leptodactylus from Aras Dam Lake, Western-Azerbaijan, Iran. Gonadosomatic index (GSI), and oocyte size were measured in females sampled seasonally in June, August, November (2011), January (2012). Development of the oocytes was categorized according to the diameter and the presence/absence of yolk granules. The ovary development was accompanied by increasing levels gonadosomatic index and egg diameter. Ovarian development histologicaly related to the seasonal GSI . This index was low in June (0.61±0.05) when oocytes started developing and reached the highest value in November (13.53±0.25), when vitellogenic oocytes were abundant in the mature ovary. Our results highlight the relationship between the ovary development and the GSI and egg diameter in the crayfish A. leptodactylus during the reproductive cycle and held important implications for the management of aquatic species. Thus, investigation of female A. leptodactylus reproduction is highly significant for fisheries managers as well as environmentalists concerned with perpetuating crayfish stocks