Effects of increasing dietary protein levels on growth, feed utilization and body composition of <i>Heterobranchus longifilis</i> (Valenciennes, 1840) fingerlings

Abstract

The effect of different dietary protein levels on growth performance and on feed utilization of catfish (Heterobranchus longifilis) fingerlings was carried out in aquaria. Five dietary protein levels 25, 30, 35, 40 and 45% were tried in triplicates. The result shows that 25% protein is too limited to ensure good growth and also the growth rate, weight gain and nitrogen metabolism increased progressively with dietary protein level to a maximum at 40%. However, there was no significant difference in feed conversion ratio (FCR), protein efficiency ratio (PER), specific growth rate (SGR), daily weight gain (DGW) and the daily feed intake between fish fed with 30% protein and those fed with 35% protein. There was no significant difference in PER and nitrogen loss (NL) between fish fed with 25 to 40% protein. Above 40% protein, nitrogen metabolism and PER decreased, showing the low utilization of dietary protein. The moisture, ash and gross energy content did not vary between dietary treatments. However, lipid and protein body content varied between treatments.

Key words: Dietary protein, growth, nutrient utilization, body composition, Heterobranchus longifilis, fingerlings.