Cryopreservation of rainbow trout (Onchorhynchus mykiss) semen

Breeding has moved beyond the point of simply propagating random stock. Genetic potential can be improved by establishing and crossing genetically defined strains, crossing species and manipulating gametes. Some of these activities require cryopreservation of semen. Cryopreserved sperm could also be a means of exchange of genetic material between locations and populations when transportation of live fish is restricted. In this study we had a survey on rainbow trout sperm quality in Genetic and Breeding Center for Coldwatwr Fishes, Shahid Motahari, Yasouj. Then Cryopreservation trials on rainbow trout (Oncorhynchus mykiss) sperm were carried out using six basic extenders. Egg batches of 25 g were inseminated with semen frozen in five 0.5-ml straws. Thowing temperature of cryopreserved sperm also was tested. In anather trial we investigate different cryoprotectant. The result showd that the best period for sperm collection in this center was from Novamber to January. The best extender based on sperm motility parameters were extender 2 and 1 with 57.2 and 56.9% fertilisatin rates, respectively. So this two extender were used in the further experiments. The best thowing temperathre was 25°C in 30s. Testing different cryoprotectant, adding 10% methanol to extender 1 gave the highest fertilization rate (64.6%) among cryoprotectant that used with this extender. In the other extender (2) adding 5% DMSO and mixture of 5% DMSO and 1% glycerol gave the highest fertilization rates (64.8% and 67.0%, respectively). In conclusion using extender 1 and 2 with mentioned cryoprotectant and thowing rate of 25°C in 30 s was recammended for rainbow trout sperm cryopreservation

Effects of sperm competition on genetic variation of rainbow trout (Oncorhynchus mykiss) progeny using microsattelite markers

In this research, the variation of spermatozoa traits among three male rainbow trout (Oncorhynchus mykiss) was used to examine how the relative influences of sperm density and duration of sperm motility account for sperm competition success. Sperm competition trial was conducted to study the fertilization ability of sperms from three male rainbow trout. The proportions of larvae sired by different males were quantified using DNA microsatellite analysis. Larvae sired by male number 2 dominated the offsprings this male sired 56% and 48% of the offspring checked in the paternity test using OMM1036 and Ocl8 loci respectively. Microsatellite DNA fingerprinting revealed that duration of sperm motility was conducive to sperm competition success. There was no significant relationship between fertilization success and either relative sperm count or duration of sperm motility sperm count showed an inverse relationship with competition success (P95%) when sufficient numbers (107) of spermatozoa per egg were used. Therefore, the fertilization success did not depend on whether sperm from one, or from a mixture of more males were used

Growth indices, feeding efficiency and survival of rainbow trout (Oncorhynchus mykiss) fed diets containing different levels of Echinacea angustifolia and Origanum majorana extracts

This study was conducted to evaluate the effects of different levels of Echinacea angustifolia and Origanum majorana extracts on growth performance, feed efficiency and survival of rainbow trout (Oncorhynchus mykiss) juveniles. Seven experimental diets with 0 (control), 0.1, 0.2 and 0.4% E. angustifolia and 0.1, 0.2 and 0.4% O. majoranawere prepared. Fish with initial weight 2.6 ± 0.3 g were randomly divided into 7 groups in triplicates and were fed with experimental diet for 4 weeks. At the end trial, the growth parameters, feed efficiency and survival were calculated. Growth and feed indices such as specific growth rate (SGR), Feed conversion ratio (FCR), weight gain, feed efficiency, average final weight, protein efficiency ratio were significantly affected by different levels of plant extracts (P0.05). However, condition factor was higher in fish fed higher levels of plant extracts. No mortality was observed during the experiment. Regression analyses showed relationship between SGR and FCR in fish fed O. majoranaextracts(P<0.05). According to the results of growth parameters and feed efficiency, it can be concluded that dietary 0.2% extract of E. purpurea and 0.1% of O. majorana have growth enhancement effects in this fish