Growth and production of milkfish ( Chanos chanos) in brackishwater ponds: effects of dietary protein and feeding levels

Abstract

The most economical combination of dietary protein and feeding levels for milkfish culture in brackishwater ponds was determined. Milkfish juveniles (average weight, 5 g) were stocked at 7000/ ha and fed two diets containing 24% or 31% dietary protein at 2 or 4% of body weight. There was no interaction between feeding level and dietary protein on growth, feed efficiency, and energy assimilation of milkfish. This indicates that the response of milkfish to change in protein levels is not influenced by ration size. Regardless of protein levels, the final weight, weight gain, specific growth rate, and production of milkfish were significantly higher (α = 0.05) when fed at 4% body weight than at 2%. As culture progresses, differences in weights of fish fed varying protein levels were still insignificant. This could be attributed to the balanced amino acid profile of both diets. The higher growth at the 4% feeding level could be due to the higher amount of amino acids available for protein synthesis. Higher energy assimilated by milkfish at higher feeding rate demonstrates that energy supply also influences growth. Partial budgeting analysis shows that bigger profits can be earned by using a 24% protein diet with balanced amino acids at a feeding rate of 4% of body weight. The greater amount of feed given at higher rate can be compensated by faster growth and higher production.