标题：The Effect of Mating Different Age Groups of Broodstocks on the Reproductive performance, Sex Ratio, Growth, and Survival bate of Rainbow Trout (Oncorhynchus mykiss)
摘要：Four breeding groups of rainbow trout (Oncorhynchus mykiss), each comprising two males and one female, different from one another based on the age of the breeders. The combinations were: age-3 males x age-3 female (Group A); age-6 males x age-6 female (Group B); age-3 males x age-6 female (Group C); aged males x age-3 female (Group D). Except for Group B, which had a low (63%) rate, fertilization rates of all groups were high and normal. Eyed-egg survival and swim-up rates were both lowest for Group B fish. After nearly one year of monitoring the offspring, the sex ratio of survivors of Groups A and B approached unity, whereas the majority of survivors in Groups C and D were males (76.8 and 89.5%, respectively). The condition factor was similar for fish of all four groups, but the average weight of females was higher than that of males in each group. Although the survival rates of fish in Groups A and B were higher, growth was better demonstrated by fish in Groups C and D. Overall, of all the mating combinations, those of young male x old female appear to be the most productive.
