Abstract

BIOCHEMICAL ESTIMATIONS OF VITAMIN C IN BRAIN AND LIVER OF RAINBOW TROUT ONCORHYNCHUS MYKISS FED ETHANOL EXTRACT OF LAPSI FRUIT (EELF) CHOEROSPONDIAS AXILLARIS (ROXB.) IN RACEWAYS FISHERIES AT NUWAKOT, NEPAL

Shubha Ratna Shakya* and Shyam Narayan Labh

Abstract

We found that vitamin C is an essential nutrient for cold water fish, the rainbow trout (Oncorhynchus mykiss). This was demonstrated by the absence of L-gulonolactone oxidase (GLO) activity, the enzyme responsible for the biosynthesis of vitamin C, in brain or liver of rainbow trout and by a feeding trial in which trout without vitamin C dietary supplementation developed poor growth rate. Vitamin C (Ascorbic acid or AA) is heat labile so directly cannot be given and it is found that lapsi (Choerospondias axillaris) contains rich amount of vitamin C in it. Thus, trout weighing 37.24±0.39 g were divided into six groups (T1, T2, T3, T4, T5 and T6), and each group was fed an ethanol extract of lapsi fruits (EELF) supplemented semi purified diet containing 0, 100, 200, 400, 800 and 1600 mg equivalent (EELF)/kg diet for 12 wk. The experiment was conducted in cold water raceways environment designed in recirculation system of water through nylon cages at SOSOD trout farm at Nuwakot, Nepal and vitamin C was supplemented in the diets as EELF which is found more stable to oxidation than AA. At the end of 90 days, trout fed no EELF had significantly lower weight gain than fish fed the EELF supplemented diets (P < 0.05). The concentration of AA in brain (51.95%) and in liver (21.63%) was higher in T4 diet group compared to trout fed with control.

Keywords: Rainbow trout (Oncorhynchus mykiss), ascorbic acid deficiency, Lgulonolactone oxidase (GLO), lapsi (Choerospondias axillaris), ethanol extract.