著者

中村 薫

出版者

鹿児島大学

雑誌

鹿児島大学水産学部紀要 (ISSN:0453087X)

巻号頁・発行日

no.29, pp.p225-238, 1980-12

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It has been commonly known that the feeding habits of decapods are affected by inevitablemoltings for their developments. In this report, the quantitative methods were applied tofeeding experiments of individual crayfish, Procambarus clarkii, for the purpose to clarify therelation of feeds to the molting cycle. Some kinds of pellets were prepared, especially suchpellets as containing much cellulose (90%) or oil (14.1%) were used for the examinations of nutritional consideration. Such item as the body weights at different stages on the moltingcycle, the diurnal amount of consumed pellets, and in some cases the amount of feces were weighed. After that, the feed conversion factor of each molting cycle, the amount of consumed pellets during one cycle/ (the body wt. of postmolt-the body wt. of intermolt), wascalculated. Further, the values of the molting power were introduced here as the indicativesof the degrees of water absorption at the molting time, which were calculated as (the body wt. ofpostmolt-the body wt. of premolt)×100/ the body wt. of premolt.As results, the diurnal amount of consumed pellets showed a distinct variation following thelapse of molting stages. Its pattern had the 1st maximum, which is also the greatest value,at the short postmolt period and the 2nd maxima were recognized in some cases before thenext molting. Such greatest values correspond to the 2-3% of their body weights, and thesummed feeds of the diurnal amounts during one molting cycle occupy about 23% of the bodyweight of intermolt. Considering with the experimental results of cellulose feeding, it suggestedthat the internal factor(s) of a feed-control mechanism if existed in the crayfish might participateprimarily with the hemolymph concentration(s)of absorbed nutritive(s) rather than the physical factor as the capacity of the digestive tract, that is the stomach and intestinal volume. Inaddition, as the pellets of much contained oil gave comparatively a high efficiency to the molting power and the feed conversion factor, it seems that lipid may propose a physiological interestfor the nutritional approach to the molting development.1. 個別飼育法でペレット飼料を給餌し,アメリカザリガニの日間摂餌量を求め摂食と脱皮成長との関係を調べた。2. 日間摂餌量は脱皮周期上の位置により著しい変動を示した。そのパターンは脱皮後期に最大値をもつ極大点を示すこと,第2極大期を次回脱皮の前に経る場合もあること,等が明らかにされた。3. 最大日間摂餌量はその体重の2-3%程に当たること,脱皮の1周期上の積算摂餌量は個体の大きさに関らず脱皮間期体重の約23%を占めることが算出された。4. セルロース給餌との比較実験の結果,摂食の制御機序には胃の容積と云った機械的要因よりも血リンパの栄養分が第一義的に関与する可能性の高いことが示唆された。5. 脂質高含有飼料の栄養試験により当該飼料は脱皮周期へは促進的効果を示さないが,脱皮時の吸水作用を高め且つ飼料係数を小さくする働きを窺わせ,脱皮成長に対して効率の良い飼料になり得る可能性を示した。