Spermatozoa quality of the tranSgenic rabbit offSpring

The objective of this study was to evaluate the spermatozoa quality of the F4 F5 generation of transgenic rabbit males carrying the mWAP-hFVIII gene in comparison to non-transgenic individuals and previous transgenic generations. Semen samples from 4 transgenic rabbits and 10 randomly selected non-transgenic males of the same breed and age were collected once a week (5 ejaculates per male were analyzed) using an artificial vagina. Each sample of fresh ejaculate was evaluated using CaSa system for concentration and motility parameters. The ejaculate volume was the same in both groups of animals, but the sperm concentration was significantly higher (p<0.001) in transgenic bucks than in non-transgenic ones. there was not statistically significant difference in motility of spermatozoa, but the progressive motility was significantly lower (p<0.001) in transgenic males when compared to non-transgenic ones. We found significant differences also in other CaSa parameters: daP, LIn, BCF (p<0.05) and dSL, VSL (p<0.01). In comparison to our previous results (F1 F3), the spermatozoa quality in the offspring (F4 F5) was similar, although the sperm concentration increased twofold, but the ejaculate volume and sperm motility were roughly the same. Our results showed good spermatozoa quality of the F4 and F5 generations of transgenic rabbit males without any reproductive disorders caused by transgenesis. Consequently the ability to produce offspring for the purpose to create stable transgenic line was retained.