Embryo cryopreservation and transfer to rederive a paternal rabbit line after 18 generations. Evaluation of growth and reproductive traits

• Autores: Jorge Daniel Juárez Moreno
• Directores de la Tesis: Jose S. Vicente Antón (dir. tes.)
• Lectura: En la Universitat Politècnica de València ( España ) en 2022
• Idioma: español
• Tribunal Calificador de la Tesis: Pilar García Rebollar (presid.), María Antonia Santacreu Jerez (secret.), Joan M. Rosell Pujol (voc.)
• Programa de doctorado: Programa de Doctorado en Ciencia y Tecnología de la Producción Animal por la Universitat Politècnica de València
• Materias:
  • Ciencias agrarias
    • Producción animal
      • Reproducción
      • Selección
• Enlaces
  • Tesis en acceso abierto en: RiuNet
• Resumen

  • To evaluate the effects of the selection process in a paternal line of rabbits, growth traits and reproductive performance from the offspring of the current generation (R36) were compared under the same environment with a control population rederived from embryos stored of a previous generation (R18). To reduce or avoid the effect of the cryopreservation process on phenotypic traits embryos of current generation (R36) were cryopreserved and transferred to obtain a third population (R37V). In chapter 1, R37V generation and offspring of 36th generation born by artificial insemination (generation R37) were compared. Differences in postnatal growth traits were observed in the three generations assessed. Although foetal growth, litter size components and reproductive traits did not show significant differences. In conclusion, cryopreservation and embryo transfer processes cause changes in growth traits of reconstituted populations that influence the following generations, without changes in reproductive traits. In the following chapters, to reduce or avoid the effects of the rederivation process, genetic drift and environmental factors on phenotypic traits, only the rederived populations were used to compare reproductive and growth performances. In chapter 2, considering that males were used to produce semen doses at insemination centres and farms, we studied whether a programme of selection by daily gain changed the seminal traits, plasma and sperm proteome and the fertility of semen when used in artificial insemination. Seminal plasma and sperm proteome from mature males of each group were analysed and semen doses were used to inseminate females. Only the percentage of abnormal sperm showed significant differences, R21 presented fewer abnormal sperm than R39. The discriminant analysis (DA-PLS) showed an effect of the generation for plasma and sperm proteome. In seminal plasma, 64 proteins were differentially expressed, 56 were overexpressed in R39 (87.5%). Sperm proteome reported 132 differentially abundant proteins, 89 were overexpressed in R39 (67.4%). Despite differences in important proteins related to capacitation, sperm motility or immunoprotection and to the fertilization process, no differences in fertility and prolificacy were detected when commercial seminal doses were used for insemination. In chapter 3, we evaluated the effect of a long-term selection for post-weaning average daily weight gain (ADG) over 37 generations. After two generations of both rederived populations (R21 vs. R39 generations), all evaluated traits showed some progress as a result of the selection. This response does not seem to affect the estimated Gompertz growth curve parameters. Results demonstrated that the selection programme had improved ADG without variations in adult body weight but, after 37 generations of selection, this trait seems exhausted. In chapter 4, we compared female reproductive traits between both rabbit populations (rederived and control). Foetal growth and litter size traits were measured in the second generation after rederivation (R20 and R38 generations). Our study suggests that selection for growth rate has no adverse effect on litter size components and the foetal sac area at day 12 of gestation, and foetal placenta area and crown-rump length of the foetus at day 19 of gestation were higher in the R38 generation. These results show that selection for growth rate does not adversely affect on reproductive performance. In conclusion, our study provides further evidence of the effects of cryopreservation on growth traits persisting two generations after rederivation. Moreover, the paternal line showed signs of genetic progress exhaustion due to low reproductive performance and high postnatal mortality. Selection by daily weight gain influenced changes in foetal growth and ejaculate proteome, but did not affect the reproductive performance of females or the fertility of seminal doses of males.