Rotation diets: A method of improving growth of cultured abalone using natural algal diets

The effect of rotating different algae in the diet of cultured South African abalone Haliotis midae was investigated. A diet rotation feeding scheme was designed to use less abundant algae, as well as the abundant kelp Ecklonia maxima. Rotation diets entailed feeding abalone on Ecklonia for 11 days of a 2-wk rotation cycle and on one of the less abundant algae species, or a mixture of the less abundant algae species, for the remaining 3 days. Six rotation diets and six single-species control diets were tested simultaneously over a 6-mo period. Shell length and body weight growths were ranked highest for the single-species diet Porphyra, but rotation diets were placed in the subsequent four ranking positions. Shell length growth rates varied between 27 and 38 μm day^-1 for abalone fed rotation diets and between 15 and 53 μm day^-1 for those fed single-species diets. Body weight growth rates varied between 34 and 55 mg day^-1 for abalone fed rotation diets and between 9 and 74 mg day^-1 for those fed the control diets. Abalone fed on rotation diets, generally, had a better body weight-to-shell length ratio.