Optimum Dietary Protein Level for Growth and Gonadal Maturation of Female Heterobranchus longifilis (Valencciennes, 1840) Broodstock
AbstractFormulated diets of varying crude protein levels (20 to 50% at 5% protein intervals) were fed to “spent” female brooders of Heterobranchus longifilis (236.0 - 243.3 g body weight) stocked in concrete tanks at ten fish per tank in order to determine the most appropriate dietary protein level for their survival, growth and egg maturation/ripeness. The fish were fed at 3% of their body weights per day twice daily (09.00 - 09.00h and 17.00 - 18.00h) for 70 days. No fish mortality was recorded in any of the treatments and the robustness/general well-being of the brooders expressed by the condition factor (K) was high with all the dietary protein levels. However, the greatest increase in body weight (270.0 g) was recorded in the fish fed 40% crude protein diet while the least increase (143.3 g) was observed in fish on the 20 and 25% crude protein diets. Specific growth rate was highest (1.07 %/d) with the 40% crude protein diet while feed conversion ratio was also best (2.6) at 40% crude protein level. Ripe brooders were observed in all the treatments but the highest number (100%) was observed in the brooders fed 40 and 45% crude protein diets. Based on the above results, 40% crude protein is recommended as the best dietary protein level for growth and gonadal maturation/ripeness of female Heterobranchus longifilis brooders.
Key words: Heterobranchus longifilis, broodstock, protein requirement.
Journal of Aquatic Sciences Vol.18(1) 2003: 29-34