Effect of dietary carbohydrate levels on the growth of fingerlings of Carnatic carp Barbodes carnaticus (Jerdon 1849)

Abstract

Fingerlings of Barbodes carnaticus (average size: 9.25 ± 0.43 cm; 7.39 ± 1.18 g) were reared for 60 days in aerated plastic tubs (40 l) providing 5 iso-nitrogenous diets formulated to contain crude NFE (nitrogen free extract) levels ranging from 35 to 50% using pure ingredients. The fish were fed ad libitum and were allowed to feed for 6 h and thereafter the unconsumed feeds were siphoned out. The following day, faecal matter was collected, dried, pooled and stored for proximate analysis. Water from each tub was replaced (50%) with freshwater every day after faecal matter collection. Proximate composition of feed and faecal matter was analysed. Crude fiber was used as the reference marker for dry matter, protein and fat digestibility determination. The growth parameters increased (p<0.05) in B. carnaticus upto dietary NFE levels of 43.72%, beyond which a decrease was noticed. The food conversion ratio (FCR) and protein efficiency ratio (PER) were the best with the diet containing 43.72% NFE. Proximate composition of fish carcass revealed the highest protein and fat contents in those fed the 43.72% NFE diet. Dry matter and NFE digestibility increased with increasing dietary NFE level upto 43.72%, whereas protein digestibility showed a decreasing trend. The study revealed a dietary NFE requirement of around 44% for the fingerlings of B. carnaticus.