Heisuke Nakagawa

Effect of Ulva meal supplementation on lipid metabolism of black sea bream, Acanthopagrus schlegeli (Bleeker)

Abstract Black sea bream ( Acanthopagrus schlegeli ) were fed on a diet supplemented with 10% Ulva pertusa meal for 143 days in indoor tanks. Ulva meal supplementation resulted in an increase in total body lipid and influenced the composition of triglycerides (TG). The similarity of the pattern of fatty acid composition between dietary lipid and the reserve lipids was relatively great in the Ulva -fed group. Wintering for 138 days without feeding caused some differences in the mode of lipid mobilization between two dietary groups. In the fish fed Ulva meal, the muscle TG were primarily exhaused prior to the visceral lipid. While specific fatty acids were selectively consumed from the lipid reserves in the control group, all fatty acids were equally mobilized in the Ulva -fed group. It was concluded that the Ulva meal supplement was associated with activation of lipid metabolism such as accumulation and mobilization. The availability of dietary algae was discussed in regard to improvement of physiological condition.

Effects of feeding frequency on the growth and body constituents of young red-spotted grouper, Epinephelus akaara

Abstract In order to obtain optimum feeding frequency in young red-spotted grouper, 25 000 fish averaging 4.7 cm in total length were divided into five groups in duplicate floating net-cages. Each group was reared with the same feeding ration to the fish weight but with different feeding frequencies: one, two, four, six, and eight times daily, respectively. High feeding frequencies resulted in high weight gain, high feed conversion efficiency, and high survival rate. The highest muscle mass and the highest levels of muscle protein were obtained at a feeding frequency of six times daily. While muscle lipid decreased with increasing feeding frequency, lipid levels of the liver and intraperitoneal fat body tended to be elevated by high feeding frequencies. Triglyceride accumulation in the whole body increased with increasing feeding frequency, but was lower in the group fed eight times daily than in the other groups. Based on the above results, a feeding frequency between four and six times daily is suggested to be optimum for achieving optimum growth rates and lipid reserves in young red-spotted grouper.

Usefulness of Ascophyllum meal as a feed additive for red sea bream, Pagrus major

Abstract Based on previous results that dietary algae meal can improve the physiological condition of fish, the effects of dietary Ascophyllum meal supplementation (0, 2.5 and 5%) on body composition and physiological condition were examined in 0 year red sea bream. Muscle protein increased in response to the algae level. Response to air-dipping and recovery time from anesthesia with 2-phenoxyethanol were improved by feeding Ascophyllum meal. These results offer support for the use of Ascophyllum meal as a feed additive in fish diets.

Growth performance in clonal crucian carp, Carassius langsdorfii. Effects of genetic difference and feeding history

Abstract Clonal crucian carp was used to assess the relative importance of disproportional food acquisition and genetic differences in ‘growth depensation’ i.e. increased variation in size-frequency distribution over time. When larval feeding was limited on the 5th, 9th, and both the 5th and 9th days after hatching in a clonal population, subsequent growth was significantly retarded compared to the group recently unlimited food (control). Suppression of growth due to limited feeding was greater when food deprivation occurred on the 5th day than when it occurred on the 9th day, suggesting that short-term disproportional feeding has a greater effect the closer it is to first-feeding. When larvae of two genetically different clones were reared together up to larval development (day 1 to 30), growth was significantly different between them. Heritability for total length was estimated as 0.257 at a low stocking density ( n = 200) and 0.584 at a high stocking density ( n = 300). Genetic factors may, thus, determine not only growth but also competitive ability in social interactions. When two strains equalized for initial size were reared to the juvenile stage (day 90 to 150), no growth differences were observed. The extent of genetic control of growth performance may differ between the developmental stages.

Effects of Ascophyllum and Spirulina Meal as Feed Additives on Growth Performance and Feed Utilization of Red Sea Bream, Pagrus major

養魚飼料への藻類添加は生理状態の向上に有効であることが明らかにされているので、本研究ではマダイについて Ascophyllum と Spirulina の効果をみた。対照区には配含飼料に5%のセルロース、Ascophyllum 区、Spirulina 区にはそれぞれ藻類の粉末を5%添加した。初期体重85gのマダイ1年魚を77日間飼育し、成長、飼料利用率、生物学的性状、体成分に及ぼす効果をみた。いずれの藻類の添加においても成長、飼料効率、タンパク質効率、筋肉タンパク質蓄積量が向上し、筋肉成分では脂質蓄積量に増加がみられた。Spirulina の投与では悪影響は認められず、各項目においてAscophyllum より優れた効果を示し、これまでに報告された藻類に匹敵するか、もしくはそれ以上の効果を示した。

Effects of Feeding Regime on Biometric Parameters and Hepatic Enzyme Activities of young Red Sea Bream, Pagrus major

体重5.1gのマダイ幼魚を5群に分けて、3つの群は日間給餌頻度を2回、4回、6回とし、49日間飽食させた。他の2群には日間給餌回数2回の飽食量相当分を4回、6回に分けて投与した。飽食給餌では給餌頻度の増加と共に摂取量、脂肪組織、筋肉脂質が上昇した反面、飼料効率、比肝重量は低下した。4回飽食の場合、腸管長は最も短く、肝臓脂質合成酵素、アミノ基転移酵素活性は高かった。一方、2回分の飽食量を4回、6回に分けて給餌した場合、脂質蓄積に変化はなかったが給餌回数の減少と共に腸管は伸張し、肝臓の糖新生関連酵素、解糖酵素活性は低下し、脂質合成関連酵素が向上した。飼料効率、脂質蓄積、腸管長、酵素活性からみて1日2回の飽食給餌が最適であることが判明した。

Studies on Rainbow Trout Egg (Salmo gairdnerii irideus) : III. Determination of Lipid Composition of Oil Globule and Lipoprotein

1. 卵黄を遠心分離して油球,低比重画分及び高比重画分(卵黄球)にわけ,それぞれの脂質の分析を行なった. 2. 油球は主にトリグリセライドから成り,他にコレステロール,そのエステル及び遊離の脂肪酸を認めた.リン脂質を全く含まないがカロチノイドに富む. 3. 低比重画分はエーテル処理により,エーテル可溶部と塩溶液可溶部を生じ,前者はトリグリセライド,遊離脂肪酸,コレステロール,そのエステル,リン脂質及びわずかながらカロチノイドを含む.後者は電気泳動によりリポ蛋白質のほか二成分の蛋白質より構成されていることを認めた. 4. 高比重画分の脂質,即ち第1報で報告したリポ蛋白質の脂質は約50%がリン脂質で,他にトリグリセライド,遊離脂肪酸,コレステロール及びそのエステルを含む.リン脂質はレシチン,セファリン,スフィンゴミエリン,リゾレシチンで構成される. 5. それぞれの画分の脂肪酸分析の結果,各画分で脂肪酸組成に相違のあることを認めた.

Genetic variation of Japanese loach inferred from restriction fragment length polymorphism analysis of mitochondrial DNA

Genetic analysis using restriction fragment length polymorphisms (RFLPs) of D-loop region in the mitochondrial DNA including the part of 12s RNA and cytochrome b genes was made to clarify genetic variations and relations and relationships among eleven populations of Japanese loach Misgurnus anguillicaudatus . Ten haplotypes were detected using seven restriction enzymes ( Alu I, Hinc II, Msp I, EcoR I, Hinf I, Hae III and Taq I). The differences between each pair of the populations were significant (p xy ) among 11 populations ranged from 0 to 15.255%, with a mean of 6.272 ±0.004% and net nucleotide divergence (d) ranged from 0 to 15.255%, with a mean of 5.312±0.004%. The net nucleotide divergence between the two northern populations (Memanbetsu and Naruko) were high (12.521%, ranged from 5.083 to 15.256%), in contrast, the net nucleotide divergence among southern populations were relatively low (3.190%, ranged from 0 to 8.478%). The bootstrapped UPGMA dendrogram and NJ tree, which were constructed based on the net nucleotide divergences, showed that loach diverged into two groups. The northern group comprised two populations (Memanbetsu, Hokkaido Prefecture and Naruko, Miyagi P.) and the southern group contained nine other populations. In the southern group, the Hashima (Gifu P.), Izumo (Shimane P.) and Tomari (Tottori P.) populations clustered into one subgroup whereas the other six populations, Yuya (Yamaguchi P.), Saito (Miyazaki P.), Nikko (Tochigi P.), Ueda (Nagano P.), Futtsu (Chiba P.), and Nasu (Tochigi P.), categorized into another subgroup. The homogeneity test and AMOVA indicated in the consensus tree reconstructed by NJ method, the two genetically groups were considerably differentiated (0.0001 African Journal of Biotechnology Vol. 4 (4), pp. 318-325, 2005

Studies on Rainbow Trout Egg (Salmo gairdnerii irideus) : IV. Changes of Yolk Content During Embryogenesis

虹鱒卵の未受精期から受精後45日迄の各発生段階における水分,脂質,蛋白質および非蛋白質成分について分析を行った. 卵黄内容物は主として孵化後に大きく変化する.蛋白質は分解され利用されるまで非蛋白態窒素化合物として貯えられる.卵黄蛋白質の電気泳動的観察では,三成分の蛋白質は全発生過程を通じ約83:11:6の割合を示し,著しい変化は認められなかったことから,これらの蛋白質は均等に分解されてゆくと考えられる. 孵化後一時的にリポ蛋白質の脂質部分が蛋白質部分より選択的に分解・利用される時期のあることを認めた. 油球の減少は全発生期間を通じ緩慢であるが,リポ蛋白質の脂質の減少は著しく,油球より利用度の高いことを認めた.

Influences of the First-feeding Delay on Subsequent Growth and Viability of Clonal Crucian Carp, Carassius langsdorfii

広島県黒瀬川由来の三倍体ギンブナー腹仔のクローン性をDNAフィンガープリント法によって確認した。それらのクローン仔魚を用いて初期摂餌開始時期の遅延が、後の成長および生残に及ぼす影響を調べた。ギンブナ仔魚は孵化後3日目で初期摂餌を開始した。孵化後4日目における摂餌を1日間遅らせた群の全長は摂餌対照群のそれに比べて有意に小さかったが、乾燥重量は摂餌の有無に関わらず変化が認められなかった。摂餌群と摂餌遅延群の核酸比は、孵化後4日目で有意差が認められた。仔魚の初期摂餌を1日および2日遅らせた群に対し、それぞれの給餌対照群を混合し、30日間飼育した。その結果、摂餌を遅らせた群の平均全長および体重は対照群のそれより有意に小さくなった。したがって、初期摂餌を遅らせることによって生じた給餌対照群との成長差は、その後も維持されることが明らかとなった。一方、30日後の生残率では、初期摂餌を2日間遅延した仔魚で高くなった。これは、初期摂餌を遅延する間に、質的に劣る仔魚が淘汰されたためと考えられた。