Effect of zinc and manganese supplementation in Artemia on growth and vertebral deformity in red sea bream (Pagrus major) larvae

Feeding trials were carried out to determine the effects of zinc (Zn) and manganese (Mn) supplementation in Artemia on growth, survival, body composition and skeletal deformity of red sea bream larvae. Triplicate groups of red sea bream larvae from 15-30 day post-hatching (dph) were fed four types of Artemia enriched with Zn (Z), Mn (M), both Zn and Mn (ZM) and without Zn or Mn (control). At 30 dph, significantly higher (P <0.05) growth performance of the fish was recorded in M group (TL=15.60±0.45 mm) compared to that of the control (TL=14.90±0.41 mm). Fish fed Artemia supplemented with only Zn and with both Zn and Mn showed similar growth performance compared to that of the control. Survival of the fish was not affected either by Zn or Mn supplementation. Increased Mn or both Zn and Mn in Artemia nauplii significantly elevated (P <0.05) crude lipid content in 30dph juvenile compared to that in the Z group. At 30 dph, Mn content in juvenile of M and ZM groups was significantly higher (P <0.05) compared to that in the other groups. Similarly, Zn content in the Z group was significantly higher (P <0.05) compared to that in the M and control groups. Skeletal deformities in the experimental fish at 30 dph were highest (P <0.05) in the control group and were significantly improved by supplementation with Zn and Mn. The major skeletal deformities were observed in the vertebral column, neural and hemal spines. In the vertebral column, occurrence of deformities in the neck, hemal and preural were higher than in other regions. The results of the present study demonstrated that maintenance of Mn level in Artemia nauplii from 12 to 42.8 μg g⁻¹ (dry-matter basis) improved growth performance of red sea bream larvae. Zn and Mn supplementation in Artemia promoted normal skeletal development of red sea bream larvae.