1Graduated from Faculty of Veterinary Medicine, Science and Research Branch, Islamic Azad University, Tehran, Iran
2Department of Aquatic Health and Disease, Faculty of Veterinary Medicine, Science and Research Branch, Islamic Azad University, Tehran, Iran
3Department of Pathobiology and Quality Control, Artemia and Aquatic Animals Research Institute, Urmia University, Urmia, Iran
4Department of Aquatic Health and Disease, Iranian Fisheries Research Institute, Tehran, Iran
5Department of Ecology and Nutrition, Artemia and Aquatic Animals Research Institute, Urmia University, Urmia, Iran
Zinc (Zn) is an essential trace element in all living organisms, and the first eukaryotic Zn uptake transporter was discovered in the yeast, Saccharomyces cerevisiae. Zinc-enriched yeast is a currently available Zn supplement. The purpose of the investigation was to compare and evaluate the effect of Zn enriched yeast in rainbow trout. The fish (mean body weight 10 ± 0.5 g) were fed a commercial diet supplemented with 0 (control), 1 × 106, 1 × 107 and 1 × 108 CFU/g of Zn-enriched yeast for 60-days. Results showed that significant increase in serum lysozyme activity, complement activity and total immunoglobulin were seen in all treatment groups during feeding trial when compared to the control group. On the basis of our findings, Zn-enriched improved rainbow trout growth, some immune parameters and disease resistance.