報告書番号

U01034

タイトル（和文）

養魚飼料添加物としてのムラサキイガイ分解・抽出物の効果

タイトル（英文）

Availability of blue mussels as supplements in the diet of Japanese flounder

概要 （図表や脚注は「報告書全文」に掲載しております）

代表的なプロテアーゼ6種類を用いむき身の分解を試みたところ、分解効果はパパインならびにトリプシンで高く、分解には50℃以上の温度条件が必要であった。むき身のパパイン、トリプシン分解物を10～20%含む飼料、ならびにむき身から熱水抽出したエキスを5～20%含む飼料を作製し、初期体重10g以下のヒラメ稚魚を6週間飼育した。酵素分解物の添加により、ヒラメの摂餌が増大し成長が促進されたが、酵素の種類や添加量による違いはなかった。また、飼料効率やタンパク質効率には影響しなかった。一方、熱水抽出エキスの場合には、同様な摂餌、成長促進効果に加え、飼料効率とタンパク質効率の向上も認められた。酵素分解物およびエキスの添加は飼料中の遊離アミノ酸、特にアラニン、グリシン含量の上昇をもたらした。これらのアミノ酸を添加した飼料を作製しヒラメ稚魚を飼育したところ、エキスの場合と同様な飼育成績の改善が認められた。

概要 （英文）

Feeding experiments were conducted to examine the availability of blue mussel as supplements in the diet of juvenile Japanese flounder Paralichthys olivaceus. Fish of less than 10 g initial body weight were fed the diets twice daily to apparent satiation each 6 days per week for 6 weeks at 20℃. Prior to the feeding experiments, enzymatic dissolution of the mussel meat was compared to detach the mussel meat effectively from the shell. Among papain, trypsin, pancreatin, carboxypeptidase, pepsin and driselase, papain and trypsin showed significantly higher activity than that of the other enzymes at 50 to 70℃. In trial 1, 10 to 20% of the control diet was exchanged with freeze-dried meat of blue mussel, mussel meats treated with papain and trypsin. The control diet mainly consisted of fish meal, potato starch, and pollack liver oil. The final body weight and weight gain of fish fed diets containing the mussel were higher than those of fish fed the control diet, although significant differences were not found except for weight gain of fish fed the diet containing trypsin treated mussel meat. The growth of fish was independent of the inclusion level of papain treated mussel meat(10 and 20%). Feed efficiency and protein efficiency ratio were similar among dietary groups tested. In trial 2, 5, 10, and 20% (weight/weight) of the control diet was exchanged with aqueous extracts of blue mussel. The final body weight, weight gain, and feed efficiency of fish fed diets containing the extracts were significantly higher than those of fish fed the control diet. However, these parameters were not different among diets containing the extracts independent of the inclusion level. A similar trend was shown in protein efficiency ratio as fish fed the control diet had a significantly lower value than the other dietary groups. In both trials, triglyceride level of fish fed diets with enzymatic dissolutions and aqueous extracts of the mussel meats was lower than that of fish fed the control diet, while other blood constituents were relatively similar for the dietary groups tested. Whole body crude lipid content and lipid retention of fish fed the mussel diets were higher than those of fish fed the control diet. Whole body crude protein was identical regardless of the dietary composition, however, protein retention of fish showed a similar trend to lipid retention. Dietary levels of free amino acids, especially alanine and glycine, increased with the inclusion of the mussels, and these amino acids are considered to the most plausible feeding attractants in blue mussels for Japanese flounder.

報告者

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