Fat metabolism plays a crucial role in the fertility of dairy cows by affecting oocyte capacity to ovulate and support early embryo development. In ovarian follicles, each cell type specifically metabolises fatty acids to provide the enclosed oocyte with specific lipids for membrane building, energy supply and cell signalling. Integrative analyses of the lipidome, proteome and transcriptome of follicular compartments provides a way to understand lipid exchanges within the follicle, and what constitutes a beneficial environment for oocyte development to improve reproductive technologies in cows.

In vitro maturation (IVM) is an inefficient tool applied in assisted reproduction and its improvement shall benefit comfort/safety of IVF patients and livestock productivity. IVM inefficiency results principally from non-physiological culture conditions, although the disrupted mechanisms are not entirely known. Our review suggests a key detrimental impact of supraphysiological FSH activity in current IVM systems on oocyte competence, as well as the possibility to improve outcomes through more physiological systems integrating new in vivo and in vitro strategies.

The rate of genetic change in cattle is slow because of long generation intervals. The generation interval in cattle is significantly reduced by the ethical collection of unfertilised eggs (oocytes) from heifer calves and using in vitro fertilisation (IVF) to produce embryos for the next generation. When combined with early genomic selection based on DNA this creates a powerful technology platform to accelerate genetic improvement in cattle to meet industry and consumer needs for optimal productivity with minimal environmental impact.

Maternal age and parity are factors to take in consideration for producing offspring in mammals. In equine, mare age and parity are confounding factors that have been shown to influence fertility by impacting reproductive tract and ovaries as well as intra and extra-uterine growth and health of foals. This review is a complete and detailed update of the literature on effects of age and parity on mare reproduction features.

Coordinated interaction between the gametes/early developing embryo and the maternal reproductive tract is essential for the establishment and maintenance of pregnancy in mammals. Extracellular vesicles can be secreted and received by the bovine embryo as well as by the oviduct and the uterus of the cow suggesting a bidirectional embryo–maternal communication. Combination of in vivo and in vitro models is fundamental to comprehend the dialogue between the embryo and the mother.

Extracellular vesicles represent nanosized particles present in almost all biological fluids and are known to shuttle bioactive molecules in form of mRNA, miRNA, proteins and lipids during cell to cell communication in reproduction. Those bioactive molecules carried by extracellular vesicles can be indicators of the physiological status of the animal and can induce stress tolerance during oocyte growth and preimplantation embryo development. They can play a significant role in signal communication between the embryo and the maternal environment during pregnancy establishment. The use of extracellular vesicles from reproductive fluids in the current assisted reproductive technologies (ART), mainly in vitro embryo production, can compensate for the missing in vivo components and thereby contribute to the improved efficiency of ART in tackling fertility problems in human and animals.

Emerging work has focused on assessing biomarkers in samples of/from oocytes or embryos that can be collected non-invasively and examining whether they predict or reflect pregnancy success. Similarly, automation is very important and also required in IVP labs as numerous parameters have to be recorded at different time points throughout embryo development, to avoid subjective decisions regarding embryo selection and transfer.

We now know that the parents transmit more than their gene, and their metabolic status in particular can influence not only the functionality of the early embryo but potentially the future phenotype of the offspring. Using transcriptomic and epigenetic molecular analysis in the bovine model, recent research has shown that parent’s age or milking level of at the time of conception generates embryos and offspring’s with a unique metabolic signature. The general common consequence of these situations is an embryo behaving as ‘economy’ mode where translation, cell division and ATP production is reduced, potentially to adapt to the perceived future environment.

This paper describes the ethical context as it applies to biotechnologies and animal use in the field of embryo technologies. Different parts of this discussion represent historical, philosophical, ethical, and technical perspective to inform reproductive biologists and veterinarians on important issues related to animal use.