Effects of polychaete extracts on reproductive performance of kuruma shrimp, Marsupenaeus japonicus Bate. – Part II. Ovarian maturation and tissue lipid compositions

A 32-day feeding trial was conducted to examine effects of marine polychaete extracts on ovarian maturation and tissue lipid compositions of Marsupenaeus japonicus. Three fractions extracted from polychaetes such as trichloroacetic-soluble (TSF), neutral lipids (NLF) and polar lipids (PLF) fractions at 0.5% (dry matter basis) were supplemented to a basal diet (BD). Frozen polychaetes (FPC) and BD were used as positive and negative controls, respectively. Each treatment with triplicate groups of ten unilaterally eyestalk-ablated wild caught females at early stages of ovarian development were fed test diets above once a day at 5:00 pm with excess of pellet diets and 10% of biomass with FPC. The ovarian development was tracked every 4 days. The maximum ovary shadow ratios (OSR = ovary width × 100 / body width) were not significantly different among treatments. Ovarian maturation time (OMT), defined as the time elapsed for ovaries to develop from initial to maximum OSR, of NLF and FPC groups were significantly shorter than those of other groups. Maturation response (MR = proportion (%) of females achieving ovarian maturity within each treatment) had some distinctive trends during the course of the trial. The study also indicated that NLF was the most effective on M. japonicus ovarian maturation and followed by TSF. Phospholipids were dominant in the ovarian lipid compositions while contents of neutral lipids were relatively high in hepatopancreas in all diet groups. Hepatopancreatic and ovarian fatty acid profiles showed significant differences in proportions of some important fatty acids. Furthermore, this study demonstrated that formulated feed being fed solely was able to promote the ovarian maturation in kuruma shrimp broodstock.

► Effects of polychaete extracts on ovarian maturation of kuruma prawn were examined.
► Three fractions from polychaetes were supplemented to a basal diet.
► NLF was the most effective on M. japonicus ovarian maturation and followed by TSF.
► Formulated feed fed solely was able to promote the ovarian maturation of shrimp.