Animal Reproduction Science 165 (2016) 31–37 Contents lists available at ScienceDirect Animal Reproduction Science jou rn al hom epage : w ww.elsevier.com/locate/anir eprosci Effects of triploidy induction on physiological and immunological characteristics of rainbow trout (Oncorhynchus mykiss) at early developmental stages (fertilized eggs, eyed eggs and fry) Shekoofeh Salimian a , Saeed Keyvanshokooh a,∗ , Amir Parviz Salati a , Hossein Pasha-Zanoosi b , Samad Bahrami Babaheydari a a Department of Fisheries, Faculty of Marine Natural Resources, Khorramshahr University of Marine Science and Technology, Khorramshahr, Khouzestan, Iran b Department of Physical Oceanography, Faculty of Marine Sciences, Khorramshahr University of Marine Science and Technology, Khorramshahr, Khouzestan, Iran a r t i c l e i n f o Article history: Received 24 October 2015 Received in revised form 4 December 2015 Accepted 9 December 2015 Available online 12 December 2015 Keywords: Rainbow trout Triploid Cortisol Thyroid hormones Immunity a b s t r a c t The aim of this study was to compare effects of triploidy induction on basal physiological and immunological characteristics in rainbow trout at three developmental stages includ- ing fertilized eggs, eyed eggs and fry. Eggs and milt were taken from eight females and six males. The gametes were pooled to minimize the individual differences. After insem- ination, the eggs were incubated at 10 ◦ C for 10 min. Half of the fertilized eggs were then subjected to heat shock for 10 min submerged in a 28 ◦ C water bath to induce triploidy. The remainder were incubated normally and used as diploid controls. Three batches of eggs were randomly selected from each group and were incubated at 10–11 ◦ C under the same environmental conditions in hatchery troughs until the fry stage. The first-feeding offspring were also reared under the same environmental and nutritional conditions for 38 days. Triplicate samples of 30 eggs (10 eggs per trough) from each group were selected 1.5 h post-fertilization and at the eyed stage. Based on red blood cell analysis, nine diploid and nine triploid fish were also selected for study. The triploidy induction success rate was 87.1%. While diploid fish had greater body weights than those in the heat-shock treatment group, weight gain (WG%) was not different between the fry of the diploid and heat-shock treatment groups. Of thyroid hormones measured, 3,5,3 ′ -triiodo-l-thyronine (T3) was less (P < 0.05) in eyed eggs of the heat-shock treatment group, but thyroxine (T4) was greater in fry of the heat-shock treatment group as compared to those that were diploid. Cortisol con- centration was greater in fry of the heat-shock treatment group as compared to those that were diploid suggesting that fry in the triploid state may be more susceptible to stressors. Concentrations of immune variables (lysozyme, ACH50, albumin, IgM, total protein, globu- lin and complement) were either comparable or greater in fry of the heat-shock treatment group suggesting that the immune system is not impaired in fish as a result of triploidy induction. © 2015 Elsevier B.V. All rights reserved. ∗ Corresponding author. Fax: +98 61 53534725. E-mail address: keyvan56@yahoo.com (S. Keyvanshokooh). 1. Introduction The induction of triploidy is an effective strategy for the production of sterile fish for aquaculture (Ihssen et al., http://dx.doi.org/10.1016/j.anireprosci.2015.12.002 0378-4320/© 2015 Elsevier B.V. All rights reserved.