Effects of Sargassum horneri as a substitute for Undaria pinnatifida in high plant protein diet for juvenile Pacific abalone (Haliotis discus discus, Reeve 1846)

Abstract

Sargassum horneri is an abundant seaweed causing golden tides on the southwestern coast of South Korea. Undaria pinnatifida is an edible and expensive seaweed conventionally used in abalone diets. The study was conducted to evaluate Sargassum horneri as a substitute for U. pinnatifida in high plant protein diets for juvenile Pacific abalone (Haliotis discus). Dried and ground U. pinnatifida and S. horneri were used for the experiment. Diets were formulated to contain 100 g kg-1 fish meal and 300 g kg-1 seaweed meal. Control diet (SA0) was prepared including 300 g kg-1U. pinnatifida meal. Three other diets were designed to contain 100, 200, and 300 g kg-1S. horneri (SA10, SA20, and SA30) by replacing U. pinnatifida meal from control. Triplicate groups of abalones stored in fifteen plastic baskets were hand-fed one of four experimental diets or dried U. pinnatifida once every other day for 16 weeks. Growth performance of abalone fed SA10 and SA20 diets were comparable to SA0 and U. pinnatifida groups. Hemolymph non-specific immune parameters were significantly higher in SA20 group compared to SA0 and U. pinnatifida groups (p ˂ 0.05). Moisture and lipid levels in edible portions of abalone fed S. horneri diets were significantly higher than in control (p ˂ 0.05). Water stability was higher in SA0 diet and gradually decreased with the increase of S. horneri meal in diets. After air exposure, abalone fed S. horneri diets exhibited higher survival than SA0 and U. pinnatifida groups. Therefore, S. horneri can be used to replace U. pinnatifida from abalone diets. The proper combination of U. pinnatifida and S. horneri meal in abalone diet containing a low level of FM appears to be approximately 100 and 200 g kg-1.