Effect of heated and unheated fish silage as a protein source in diets for abalone Haliotis fulgens

Abstract

Both unheated (US) and heated (HS) fish silage were evaluated as sole dietary protein sources in an artificial diet for the culture of juvenile abalone Haliotis fulgens. The fish silage was heated to reduce the level of hydrolysis and thereby increase the availability of nutrients. After 140 d of culture, growth rates of abalone fed the US- and HS-containing diets were 16.4 and 19.8 μm/d and were not significantly different despite greater leaching of protein and carbohydrate in the US-containing diet. Growth rates achieved with the US- and HS-containing diets were significantly lower than that achieved by feeding a commercially available diet used as a reference diet. Abalone that were fed the US- and HS-containing diets were then switched to a diet in which two-thirds of the total amount of silage was replaced with fishmeal. At the termination of the experiment, day 217, the abalone originally fed the US and HS diets had composite growth rates of 24.3 and 23.5 μm/d, while abalone that continued to be fed the commercial diet had a growth rate of 18.6 μm/d. Stability of the dry matter of the diets was not related to the level of protein leaching. Fish meal outperforms fish silage as a dietary protein source for abalone. However, growth rates achieved still fall short of that needed to achieve a market size product within a 2-yr period of growth.