Blood Properties of Cultured Yellow Tail, Seriola quinqueradiata Temminck and Schlegel : I Effect of Disease Caused by Anchovy, Engraulis japonica HOUTTUYN, as Diet

養殖ハマチの血液性状 : I. カタクチイワシ投餌の影響

Nanba Kenji

Nakagawa Heisuke

Murachi Shiro

Kayama Mitsu

Nakamura Tatsuo

広島大学水畜産学部紀要

Journal of the Faculty of Fisheries and Animal Husbandry, Hiroshima University

養殖ハマチの主たる餌料であるカタクチイワシに起因する食餌性疾病の本態を究明するために,200尾のハマチにカタクチイワシを単一投与し,これを試験群とし,同時にイカナゴを単一投与した200尾のハマチを対照群として,50日間の飼育を行い,試験群に生ずる食餌性疾病の影響を血液性状,成長,肝蔵重量等について調べた.得られた結果を以下に示す.

1) 試験群では実験開始10日後には摂餌の不活発,成長の遅れ,軽度の肝萎縮等が認められ,20日後には食餌性疾病による斃死が始まり,実験終了時までに試験群の約50%が斃死した.斃死魚に見られる特徴は,体色の変化(主として黒変),肝萎縮,眼球突出などであった.

2) 試験群は血漿蛋白質量の減少及び低い血漿総コレステロール量を示したが,ヘモグロビン量及びヘマトクリット値については,斃死が盛んな時期においても,対照群に比較して有意な差を示さなかった.

3) 試験群においては,血漿蛋白質量の減少及びA/G比の変化から,グロブリン画分の減少が推測された.

4) ハマチの血漿蛋白質には電気泳動的に,6成分が認められ,両群においてIII画分の組成比の変化が認められた.

5) リポ蛋白質画分は対照群ではIV画分に相当したが,試験群では一定せず,III,IV,V,VI画分にわたり不明瞭な脂質の染色が認められた.

6) 試験群においては,セルローズアセテート膜上の,リポ蛋白質の染色が不明瞭である事,及び血漿総コレステロール量の減少から血漿脂質の減少が考えられた.

7) 試験群の脂質のTLCから,トリグリセライドの著しい減少と,それに相対的なワックスエステルの増加が認められた.

Investigations have been carried out in view of verifying the effects of the disease caused by anchovy, Engraulis japonica, as a diet, on the blood properties of cultured yellow tail, Seriola quinqueradiata.

Yearling yellow tail were fed for 50 days with two different diets, i.e. one was anchovy as an experimental diet and the other was sand launce, Ammodytes personatus, as control.

The results can be summarized as follows:
i) Fish fed on anchovy showed a loss of appetite and a retarding growth after about 10 days; exhibited abnormal swimming patterns, change of body color, and atrophy of the liver after about 20 days; mortality mounted to about 50% at the end of 50 days while that of control group remained at 5% level. The dead fish showed a remarkable change of body color, severe atrophy of the liver, and protrusion of the eye-balls. The liver weight of fish fed on anchovy was smaller than that of control fish.
ii) Hemoglobin concentration and hematocrit value did not differ significantly in both groups.
iii) Total plasma cholesterol concentration of fish fed on anchovy stayed almost unchanged with their growth, while those of the controls increased.
iv) Total plasma protein and A/G ratio of fish fed on anchovy decreased with the progress of the disease. Those decreases both in total plasma protein concentration and A/G ratio indicated a decrease of globulin fraction. A/G ratio of control group, however, decreased more noticeably.
v) Cellulose acetate electrophoresis separated the plasma protein of yellow tail into six major fractions. The electrophoretic pattern varied especially on plasma fraction III.
vi) The main lipoprotein fraction agreed to the plasma fraction IV. Fish fed on anchovy freqnently lacked a lipoprotein corresponding to plasma fraction IV.
vii) The considerable decrease of plasma lipid of the fish fed on anchovy was judged to be due to a lower degree of staining intensity for lipid and to the decrement of total plasma cholesterol concentration.
viii) In the lipid classes of fish fed on anchovy, low proportions of triglycerides and phospholipids and high proportions of wax esters were noticed.

Fishing industry. Fisheries [ 660 ]

eng

広島大学水畜産学部

[ISSN] 0440-8756

[NCID] AN00213563

[NAID] 40018463830