Effect of male age in Rainbow Trout (Oncorhynchus mykiss) on duration of sperm motility, spermatocrite and eyed egg rate production

Abstract

Effects of three levels of Rainbow Trout male age (2+, 3+ and 4+ years old), on duration of sperm motility, spermatocrite and eyed egg rate in rainbow trout were studied in Kelardasht Fish Breeding Center. The sperm from 2+ year old males activated by water showed the shortest motility (24.86 sec) (P= 0.007), while those of the 3+ and 4+ years old revealed the longest sperm motility. No significant difference was found between sperm motility of the 3+ and 4+ males. The average spermatocrite in different age groups of male fish was significantly different. This was showed to be 32.66% in 2+ years and 2126 % in 3+ year's male age groups respectively. Eyed egg rate was highest in 2+ years age (86/82%), and was significantly different with the 3+ age group (P=0.02). The eyed egg rate of the 4+ age group was not significantly different with those of the 2+ and 3+ age groups.