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Formulated diets enhance reproductive performance of purple mangrove crab broodstock: study

Broodstock fed with formulated diets had best performance for maturation, egg quality and fertility.

“Adequate nourishment using diets supplemented with ingredients of proven physiological value is vitally important not only in maturation of broodstock, egg quality and hatching rate, but also survival, molting and growth of the juveniles,” Thien Fui Yin and Dr. Annita Yong Seok Kian said in Effect of different maturation diets on reproductive performance of the broodstock of purple mangrove crab, Scylla tranquebarica. They are with the Borneo Marine Research Institute, Universiti Malaysia Sabah.

Synthetic astaxanthin with 10 percent purity and DHA oil with 80 percent purity were used in the study.

Astaxanthin is the major carotenoid – organic pigments in shrimp and crab – which they need to obtain from diet.

DHA is an omega-3 fatty acid that is a primary structural component of the brain, cerebral cortex, skin and retina.

Among all the treatments, the broodstock fed the Astaxanthin +DHA (FA+D) diet showed significantly higher maturation percentage, spawning rate, gonadosomatic index, oocytes diameter, ovary colour intensity, sperm viability, and molting rate than broodstock fed diet without these substance (Fcon).  

Molt death syndrome and mortality was also “significantly lower” in broodstock fed FA+D diet.

“Likewise, results on the larvae showed the FA+D diet group had higher fecundity, hatching rate, total number of larvae produced and significant higher zoea II survival than Fcon group,” they said.

Formulated diets provide a better alternative over natural food in terms of quality and supply. “The quality of natural food varies seasonally and can influence the process of maturation. Natural food deteriorates fast and requires proper storage, without which its nutritional value is diminished. These items also impair the water quality if left in the tank for extended periods,” they explained.

Experiment results were consistent with those of previously conducted researches on various crustacean broodstock, such as green mangrove crab, mitten crab, Chinese prawn, freshwater prawn and tiger prawn.