The production of donor derived gametes through xenogenesis is an emerging biotechnology for producing hybrid catfish (channel catfish, Ictalurus punctatus ♀ × blue catfish, I. furcatus ♂) embryos. In this study, the reproductive success of xenogenic white catfish (Ameiurus catus) transplanted with donor germline stem cells from blue and channel catfish was evaluated following transplantation at different days post-hatch (DPH). Pairing of xenogenic males and females was conducted according to their transplantation DPHs. Gravid females were administered intraperitoneal injections of luteinizing hormone-releasing hormone analogue to induce the spawning. Following the spawning, reproductive performance was evaluated among xenogenic, and control groups.
Donor germline stem cells transplanted between 3 to 7 DPH were capable of producing donor-derived progeny, with the highest proportion observed in recipients transplanted at 4 to 6 DPH (60.0 - 72.7%). There was no significant difference in relative fecundity between xenogenic white catfish producing channel × blue hybrid progeny (channel catfish eggs fertilized by xenogenic white catfish males) (4608.1 ± 1675.9) and control channel catfish females (4546.4 ± 1712.2; P > 0.05). However, xenogenic white catfish exhibited significantly higher relative fecundity compared to control white catfish (2619.1 ± 756.0) and xenogenic white catfish females producing blue catfish progeny (blue catfish eggs) parents (1202.4 ± 261.3; P < 0.05). Similarly, there was no significant difference in fry yield per kilogram of female broodstock between xenogenic white catfish producing channel × blue hybrid progeny (2981.8 ± 787.7) and control channel catfish producing channel catfish progeny (2882.6 ± 584.2; P > 0.05). In contrast, fry yield per kilogram of females was significantly higher in xenogenic white catfish producing channel × blue hybrid progeny compared to control white catfish (1950.4 ± 548.3) and xenogenic white catfish parents producing blue catfish progeny (780.1 ± 331.8; P < 0.05). There were no significant differences for the hatching rates (> 66.5 ± 9.4%) among four groups.
These results demonstrate the suitability of white catfish as a host species for xenogenesis when stem cells are transplanted between 4 and 6 DPH, and an alternative technology to produce hybrid progeny without sacrificing blue catfish males. These differences in relative fecundity and ultimately fry output were a result of a major impact of the donor species on fecundity and egg size relative to that of the host species.