Fertilization quality of sperm with different chromosomes (XX and xXY) from male rainbow trout (Oncorhynchus mykiss)

An increase in the levels of environmental pollution and ecological problems due to rapidly growing global population and technological developments leads to a decrease in the sources of animal protein. These problems make it necessary to obtain more animal protein from a unit area. At this point, aquaculture comes to the forefront. In recent years, the studies aiming to increase the yield in aquaculture have gained cosiderable importance. Especially, biotechnological studies in this way have a great importance. Among these studies, breeding researches have always the first place. In this study, the fertilization quality of the sperms with XX and XY chromosomes from male rainbow trout (Oncorhynchus mykiss) was determined. For this purpose, the quality of the sperms (semen volume, sperm density, sperm motility ratio, sperm motility duration, pH and total sperm number), gonadosomatic index value and fertilization ratio of the sperms for two ovum were investigated. In addition, fertilization, eyed and hatching rates of eggs and hatching duration of larvae fertilized by these sperms were observed.In the experiment, it was used the ovum from female brood fish which were identified to be 2685±55 g at age 4 and male with XY chromosomes (ordinary) with mean weight of 1470±35 g at age 3 and male with XX chromosomes (transformed) weighting 1470±35 g and at age 3. The mean values for absolute and relative fertility rates in these females were 4730±50 and 2156±18 respectively. These ova were used to determine the sperm?s quality to fertilize. In this study, the best results with regard to the sperm quality parameters (semen volume, first motility ratio, motility duration, and total sperm numbers) examined, fertilisation, eyed and hatching rates of eggs and hatching duration were obtained from the sperms with XX chromosomes (P<0.05). It was also found that the gonadosomatic index values of the fish with XX chromosomes were significantly higher than those of the fish with XY chromosomes (P<0.01). However, eyed and hatching duration of eggs were not found to be significant statistically (P>0.05).In this study, it is obvious seen that fertilisation by sperms with XX chromosomes is more productive than fertilization by sperms with XY chromosomes in the trout culture. When the brood male rainbow trout with XX chromosomes are used throughout the country, the yield will substantially increase. This will provide in higher number and quality offspring.Key words: Rainbow Trout, Brood, Fertilization, Quality, Chromosome, Sperm.