Effects of varying dietary protein levels on growth, reproductive performance, body and egg composition of rohu, Labeo rohita (Hamilton)

Abstract

A 360-day feeding trial was conducted to observe the influence of varying levels of dietary protein on growth, reproductive performance, body and egg composition of rohu, Labeo rohita. Twenty fish (40.4 ± 0.24 cm; 852 ± 4.9 g), stocked in outdoor concrete tanks (200 m2), in duplicate, were fed diets with varying levels (200, 250, 300, 350 and 400 g kg−1) of crude protein exchanged with carbohydrate to apparent satiation, twice daily, at 09:00 and 17:00 h. Higher (P < 0.05) weight increment was discernible in fish fed dietary protein ≥300 g kg−1. Gonadosomatic index was comparable (P > 0.05) among fish of different dietary groups except those fed 200 g kg−1 protein diet which produced least values. Egg diameter remained unaffected (P > 0.05) by variations in levels of dietary protein. Relative fecundity was maximum (P < 0.05) in fish fed 250 and 300 g kg−1 protein diets. With the exception of fish fed 200 g kg−1 protein diet, fertilizability (%) remained unaffected (P > 0.05) by variations in dietary protein level. Hatchability (%) followed the trend of variations almost similar to that of fertilizability. Proximate composition of muscle and eggs varied significantly (P < 0.05) with dietary protein levels. For broodstock L. rohita, a dietary protein level of 250 g kg−1 was found optimum with regard to its reproductive performance, egg quality and composition.