Work Package 6 – Fertility and Reproduction

Rationale: Efficient and unrestricted reproduction is important for the viability of livestock production enterprises. In dairy cattle, for example, selection for improved milk yield has seen concurrent reductions in fertility, especially expressing itself as abnormal ovarian cyclicity, poor oestrus expression and failure to establish successful pregnancy after insemination (fertilization failure and embryonic loss). Getting cows pregnant again at an optimum time after calving is considered a major problem for the dairy industry.

Direct genetic selection for fertility is hampered by a relatively low heritability of the trait and the lack of easy-to-measure parameters for fertility with higher heritabilities. Knowledge of the regulation of the cascade of processes underlying successful reproduction (resumption of ovarian cyclicity after calving, maintenance of regular cycles until pregnant, oestrus expression, folliculogenesis, ovulation, luteal function, embryonic developmental competence, embryo-maternal interactions, foetal development and survival) will improve the possibilities for breeders to increase the genetic merit of farm animals for fertility and reproductive success while further improving the genetic merit for productivity in general.

Successful pregnancy at an optimum stage of lactation depends on many factors. Critical factors are currently oestrus expression and embryonic survival. The transcriptomic research in this WP has therefore focussed on the genetic regulation of female sexual behaviour (related to oestrus expression) and oocyte and embryo developmental competence (related to survival in the course of mbryogenesis). Further, this WP has included fine-mapping and further identification of a segregating QTL (BTA7) for conception rate.

The aim of this work package was to generate fundamental knowledge of the genomics of important aspects of reproduction and fertility in large domestic animals. This knowledge will enable the development of successful breeding strategies for improved reproduction efficiency. As such, it will contribute to more sustainable livestock production.

Objectives for WP6 at start of SABRE 

• Identification in dairy cattle of genes involved in female sexual behaviour 
• Identification of genes involved in folliculogenesis 
• Identification of genes involved in embryonic developmental competence 
• Development of a protocol for in vitro production of well-defined preimplantation embryos for transcriptome analysis 
• Fine mapping of a segregating QTL (BTA7) affecting conception rate in dairy cows 
• Contribution to the development of a phenotype ontogeny database concerning reproduction traits of interest for livestock production (in collaboration with WP3)

Results: Please see the results section at the right side of this page.

WP Leader: Dr Henri Woelders (ID-Lelystad)

Partners involved:

• ID-Lelystad
• University of Aarhus Faculty of Agricultural Sciences
• Institute National de la Recherche Agronomique
• MTT Agrifood Research Finland
• Agricultural Research Organization, The Volcani Center
• University of Bonn