Tuna by-product meal as a dietary protein source replacing fishmeal in juvenile Korean rockfish Sebastes schlegeli

Kyoung-Duck Kim,Kang-Woong Kim,Bong-Joo Lee,Hyon-Sob Han,Sang Woo Hur,Ji Won Jang

doi:10.1186/s41240-018-0107-y

Kyoung-Duck Kim, Kang-Woong Kim + Show 4 more

Open Access

https://doi.org/10.1186/s41240-018-0107-y

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Abstract

This study was conducted to evaluate the use of tuna by-product meal (TBM) as a substitute for fishmeal in juvenile Korean rockfish (Sebastes schlegeli) diets. Five isonitrogenous (52% crude protein) and isocaloric (4.9 kcal/g) diets were prepared. Control diet (Con) was formulated to contain brown fishmeal, whereas 25, 50, 75, and 100% of fishmeal was substituted with the same percentage of TBM in the TBM25, TBM50, TBM75, and TBM100 diets, respectively. Three replicate groups of fish (initial weight, 29.5 ± 0.6 g) were fed one of the five diets for 12 weeks. The mean weight gain of fish fed the Con and TBM25 diets was significantly higher than that of fish fed the TBM100 diet (P < 0.05), but it was not significantly different from the weight gain of fish fed the TBM50 and TBM75 diets. The feed efficiency and protein efficiency ratios of fish fed the Con diet were significantly higher than those of fish fed the TBM100 diet (P < 0.05), but were not significantly different from those fed the TBM25, TBM50, and TBM75 diets. The TBM25, TBM50, TBM75, and TBM100 diets had significantly (P < 0 .05) lower incidence cost and higher profit index than the Con diet. These results suggest that the tuna by-product meal used in this study could replace up to 75% of fishmeal protein in the diet without reducing growth and feed utilization in juvenile Korean rockfish weighing 29–53 g. By considering feed cost, the TBM 75 diet is recommendable for Korean rockfish farming.

Highlights

Fishmeal is the most important protein source for fish culture feed due to its high-protein content and good balance of essential amino acids
Crude protein and essential amino acid contents of tuna by-product meal used as substitute of fishmeal in diets were slightly lower than those of brown fishmeal (Table 2)
In a previous study (Jeon et al 2014), fishmeal could be replaced by tuna by-product meal prepared by fermenting a mixture of tuna fishmeal and soybean meal up to 40% without diminishing the growth of juvenile Korean rockfish (3–12 g), which is lower than the 75% replacement of fishmeal in this study

Summary

Introduction

Fishmeal is the most important protein source for fish culture feed due to its high-protein content and good balance of essential amino acids. High-quality fishmeal used in Korea is mainly imported from South American countries such as Chile (KITA 2016). Their prices are unstable, generally increasing due to fluctuations of raw fish catches. High contents of good quality fishmeal in diets generally result in improved fish growth and feed efficiency (Vergara et al 1999). Considering both price and quality of fishmeal, it is very important for efficient fish culture management to use proper fishmeal in diets to reduce feed costs while improving the growth of cultured fish

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