Effect of dietary dha and carotenoid on reproductive performance of purple mangrove crab (scylla tranquebarica) broodstock

In mangrove crab seed production, it is important to provide the broodstock with maturation diet that can improve the reproductive performance. For the purple mangrove crab (Scylla tranquebarica), a dominant mangrove crab in Sabah, there are limited study on its maturation diet. Therefore, the prese...

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Bibliographic Details
Main Author: Thien, Fui Yin
Format: Thesis
Language:English
English
Published: 2019
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Online Access:https://eprints.ums.edu.my/id/eprint/41355/1/24%20PAGES.pdf
https://eprints.ums.edu.my/id/eprint/41355/2/FULLTEXT.pdf
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Summary:In mangrove crab seed production, it is important to provide the broodstock with maturation diet that can improve the reproductive performance. For the purple mangrove crab (Scylla tranquebarica), a dominant mangrove crab in Sabah, there are limited study on its maturation diet. Therefore, the present study was conducted to investigate the suitable maturation diet for the purple mangrove crab. Formulated diets (46% crude protein, 12% crude lipid) were prepared by adding astaxanthin (500 mg kg-1) (FA), DHA (10 g kg-1) (FD), both astaxanthin and DHA (FA+D) and without astaxanthin and DHA (Fcon). Natural food (NF) was comprised of trash fish (Valamugil sp.), shrimp (Penaeid sp.) and mangrove clam (Polymesoda sp.). Immatured female broodstock of initial body weight 129.07 ± 17.03 g and male 125.30 ± 14.12 g were cultured under recirculating water system for 50 weeks with the ratio of 1:5 (male:female). Reproductive performance of the broodstock was routinely monitored. Matured females (n=3) were identified and sacrificed for gonadosomatic index (GSI) estimation and biochemical analysis while others were allowed to spawn. The male broodstock (n=3) also sacrificed to determine the sperm viability. Newly hatched larvae (from one hatching) were measured (n=30), subjected to resistance tests (ammonia, dissolve oxygen, salinity and starvation) and reared until zoea II to determine the survival rate. The results revealed that the broodstock fed FA+D showed significantly higher maturation and spawning rate than broodstock fed Fcon, however, it showed no significant different with broodstock fed NF. Broodstock fed FA+D also showed significant better results than Fcon and NF in term of GSI, ovary colour intensity, oocyte diameter, molting rate, molt death syndrome (MDS) and male sperm viability. Broodstock given FD and FA diets resulted in significantly better results than NF group in term of GSI, oocytes diameter and sperm viability (P<0.05). However, the broodstock fed FD, FA and NF diets were not significant different to each other in term of maturation, spawning, molting, MDS and mortality (P>0.05). On the other hand, broodstock fed FA and FA+D diets showed significantly greater total carotenoid accumulation in the ovary than other treatments corresponding to the ovary colour intensity (P<0.05). However, total carotenoid accumulated in the female hepatopancreas was not significant different among the treatments (P>0.05). Broodstock fed FD and FA+D diets also showed significantly higher DHA accumulation in the ovary and hepatopancreas than those fed Fcon diet (P<0.05) but not significantly different with FA and NF groups (P>0.05). Larval from broodstock fed FA+D diet showed higher hatching rate, total number of larvae and significantly higher zoea II survival than Fcon group (P<0.05). Likewise, larval resistance tests showed that the larvae produced by broodstock fed FA+D diet showed significantly higher survival rate than Fcon and NF groups in all of the tests. In conclusion, formulated feed that supplemented with DHA and astaxanthin is a better maturation diet than the natural food for purple mangrove crab. The maturation diet provided also affected the early stage larval quality with best quality observed in larvae produced by the broodstock fed DHA and astaxanthin.