Traitement ciblé de l'infertilité post-partum chez la vache laitière

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The number one problem in dairy cows profitability is low fertility which causes delays, treatments and premature culling. The low fertility is the product of a combination of several factors but seems to peak at around day 60 post-partum exactly at the time where producers are starting to inseminate. The analysis of the post-partum context indicates the potential factors involved in low fertility: incomplete uterine involution, infection, mastitis and inflammation status but the most likely suspect is the negative energy balance caused by high milking cows, limited intake capacity, suboptimal quality of food etc. Therefore, we have analysed the ovarian perspective by looking at the complete response to the environment using the powerful transcriptomic approach. We first looked at the synchronized dominant follicles of cows at different period post-partum 30-60-90 and 120, using 120 days as the control reference and illustrates that at 60 days a few gene pathways are not functioning correctly in these follicles, especially the retinoic acid dependant path.A metabolic analysis of the animals according to BHB (beta hydroxy butyrate) level has identified 2 pathways under expressed in these animals: vitamin A and vitamin D dependant pathways. To translate the genomic information into practice we have design a simple experiment that would serve as a preliminary intervention on a reduced scale to justify a larger clinical trial. Post-partum animals will be selected at 50 post-partum based on the absence of obvious diseases which would impact fertility. The animals will be sampled for blood BHB measurements. Half of the animals (24) will be treated with 2 injections of vitamins A-D at days 50 and 70 and the other half will serve as control (24). In addition, the impact on the number of open days, insemination and veterinary cost to obtain a pregnancy will be compared. The goal is to provide a simple individual treatment to high BHB cows in the critical period for insemination. This concept may seems too simplistic but it seems that the ovary can sense the seasonal context as fresh grass (vit A) and spring (vit D) as metabolic indicator of future energy supply and facilitate fertility.