出版社:International Medical Journal Management and Indexing System
摘要:An experiment was performed to appraise the biological performances and ingestive
behavior of Nile tilapia (Oreochromis niloticus). In this respect, we examined three tilapia
stocking densities; low density (LD, 100 fish m-3
), medium density (MD, 200 fish m-3
) and
high density (HD, 400 fish m-3
). Lately, Aeromonas hydrophila defied fish evaluated
through calculating the cumulative mortality (%). Stocking density had no influence on
survival rate while, the final weight markedly reduced with increased density. The
ingestive behavior was higher in MD- reared fish than the LD-reared group, however, fish
at HD had a higher feed intake (%) and feed conversion ratio. Fish at LD showed marked
higher levels of total protein, albumin and globulin compared with those reared at HD. The
plasma glucose and cortisol levels elevated in HD-raised fish contrast to LD and MD
groups. LD-raised fish had more elevated RBCs and WBCs parallel to MD and HD.
Similarly, lymphocytes, neutrophils, and monocytes (%) decreased with increasing
density. Also, Serum antioxidant and lysozyme enzymes were considerably (P<0.05)
higher in LD compared with MD and HD groups. Meanwhile, the Phagocytic index
expressively increased in MD-raised fish compared with LD and HD groups. Finally, the
HD -raised fish showed a markedly higher cumulative mortality (%) (χ
2= 6.257**) than
the MD and LD-raised fish. In light of these results, a high-density culture evolved chronic
stress in Oreochromis niloticus and consequently altered the biological performances,
ingestive behavior with a subsequent immune depressive effect as displayed by the
cumulative mortality (%).