報告書番号

V08008

タイトル（和文）

付着生物有効利用技術の開発 - 養殖飼料添加物としてのムラサキイガイの効果 -

タイトル（英文）

Availability of blue mussels as feed ingredients for tiger puffer

概要 （図表や脚注は「報告書全文」に掲載しております）

トラフグを対象に、大豆粕を魚粉代替原料とした飼料におけるムラサキイガイの添加効果を明らかにするため、以下の検討を実施した。
魚粉を主原料とした飼料を対照区とし、魚粉タンパク質の20～60%を大豆粕或いは大豆粕とムラサキイガイ軟体部乾燥粉末で置換した飼料で初期体重11gのトラフグを8週間飼育した。大豆粕だけで置換した場合の成長は大豆粕含量の増加に伴って低下し、40および60%置換区では対照区に比べ有意に劣ったが、軟体部を一定量含む飼料区では対照区と同等の成長を示した。
対照区の魚粉タンパク質の30および40%を大豆粕で置換するとともに、ムラサキイガイエキスを0～30%添加した飼料により初期体重18gのトラフグを7週間飼育した。魚粉を大豆粕だけで置換した場合の成長は対照区に比べ有意に低かった。30%置換区では、エキス添加量の増加に伴って飼育成績が改善され、10%添加区では対照区と同等の結果が得られた。40％置換区でも同様の傾向が認められたものの添加効果には上限のあることが示唆された。
結晶アミノ酸を添加した飼料を用いた飼育実験から、ムラサキイガイに含まれる遊離のアラニンがトラフグにおける摂餌促進原因物質であることが示唆された。

概要 （英文）

Feeding experiments were conducted to examine the availability of blue mussel as supplements in the diet of juvenile tiger puffer Takifugu rupbripes. Fish of less than 20 g initial body weight were fed the diets twice daily to apparent satiation each 6 days per week for 7 or 8 weeks at 20C.
The potential use of defatted soybean meal (SBM) and freeze dried meat of blue mussel (BM) as partial replacement of fish meal in the diet of tiger puffer were examined. Eight experimental diets were formulated, in which 0, 20, 40 and 60% fish meal protein were replaced with SBM (S0B0, S20B0, S40B0, and S60B0), and 40 and 60% with a combination of SBM and BM (S30B10, S20B20, and S45B15, S30B30). Specific growth rate, feed efficiency, and protein efficiency ratio of fish fed diets containing SBM as an alternative protein source for fish meal decreased with increasing level of SBM, and these parameters of fish fed S40B0 and S60B0 diets were significantly lower than those of the control. Growth of fish in dietary groups containing BM were statistically identical to those in the control, and tended to increase with increasing level of dietary BM both at 40 and 60% substitution levels. Growth and feed utilization of fish fed S20B20 were almost the same to those in the control.
Inclusion of the water-soluble fraction of blue mussels as a feed additive was examined. Experimental diets were formulated to replace 30 and 40% of the fish meal protein in the control diet with SBM, and were supplemented with 0 to 20% mussel extracts. Weight gain and protein efficiency ratio of fish fed the diet containing SBM without the extract were significantly lower than those of the control at the 30% replacement level. Addition of 5 or 10% extracts improved the growth and feed utilization to levels comparable to those of the control. At 40% substitution, statistically identical growth and feed performance to the control were obtained for diets supplemented with 10 or 20% extract, however, the 5% addition were significantly lower. Thus, the water-soluble fraction of blue mussels would be an effective feeding stimulant in aquaculture feed for tiger puffer that makes it possible to replace 30 to 40% of fish meal protein with SBM.
Dietary levels of free amino acids, especially alanine and glycine, increased with the inclusion of the mussels, and alanine is considered to be the most plausible feeding attractant in blue mussels for tiger puffer.

報告者

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