Dairy cows’ fertility has been shown to be declining in many countries, possibly due to selection based on their milk production traits, without enough consideration for reproductive performance. Economic repercussions of this impaired fertility warrant investigation into its underlying mechanisms.
Many factors have been proposed to be relevant, including the animals’ energy balance. Negative energy balance after calving, to a high extent due to milk production, predisposes cows to nutritional and hormonal imbalance and these imbalances have been associated with decreased fertility.
Our previous work found that in New Zealand Holstein-Friesian dairy cows 30% of the embryo losses occurred before day 7 after insemination. It was also found that only 29.6% of cows inseminated on their first oestrous cycle after calving (OAC) carried a viable embryo at day 7, compared to 60% for those inseminated on their third or more OAC.
The aim of this study is to investigate proteomic and metabolomic differences in the uterine environment between these two physiological states through analysis of uterine flushings at day 7 after insemination.