Current status & prospects of farming the giant river prawn (Macrobrachium rosenbergii de Man 1879) in Thailand

Thailand was second only to P.R.China in annual production of giant river prawn. This article briefly describes the seed production of giant river prawn technology in Thailand and notes that broodstock management has paid scant attention to genetic issues. There are, however, ongoing selective breeding programmes on giant river prawn aimed to improve growth and disease resistance. In the conventional culture technology, postlarvae are stocked at a high density and prawns are harvested partially. The cropping period is long and the practice has led to disease outbreaks and deteriorated pond bottoms that result in frequent detection of antibiotic residue. The improved culture technology involves manual sexing of the prawns at 3 months and restocking only the male prawns into new ponds at low density. The technique gives higher yield and reduces incidence of disease and thus the need for prophylactics. The constraints to giant river prawn culture business in Thailand include low yield and a limited export market. The article describes three ways to expand and sustain the business of giant river prawn farming in the country: development of more genetically improved strains; culture of all‐male stock, and new culture techniques.     

The Use of Natural Carotenoids and Growth Performance,Skin Pigmentation,and Immune Response in Fancy Carp (Cyprinus carpio)

Fancy carp were fed seven dietary treatments with natural pigment sources (tea, mulberry, cassava) at a specific rate to achieve a total carotenoid (TC) concentration in the diet of 25 mg/kg. Growth performance among treatments was not significantly different (p ≥ 0.05). TC and skin redness (a*) of fish fed tea leaves was higher than the other treatments (p ≤ 0.05). Fish fed with tea extract and cassava leaves had higher serum astaxanthin concentrations than the other groups (p ≤ 0.05). This group also retained serum astaxanthin and red color better than other groups two weeks post treatment (p ≤ 0.05). Phagocytic activity was significantly greater in fish fed carotenoid supplements compared with the control group (P ≤ 0.05). Therefore, dietary supplementation with 25 mg/kg tea leaves is sufficient to obtain good coloration in fancy carp as well as enhance immunity.