1 Vol.:(0123456789) Scientifc Reports | (2020) 10:20798 | https://doi.org/10.1038/s41598-020-77604-y www.nature.com/scientificreports Efects of dietary n‑3‑PUFA supplementation, post‑insemination plane of nutrition and pregnancy status on the endometrial transcriptome of beef heifers Carla Surlis 1 , Paul Cormican 1 , Sinead M. Waters 1 , Patrick Lonergan 2 , Kate Keogh 1 , David N. Doyle 1 & David A. Kenny 1,2* Supplementation of cattle diets with n‑3‑polyunsaturated fatty acids (PUFA) can improve reproductive efciency. Conversely, short‑term fuctuations in feed supply can impact pregnancy establishment. The objectives of this study were to examine the efects of (1) dietary supplementation with n‑3‑PUFA and (2) post‑insemination plane of nutrition on the endometrial transcriptome. Beef crossbred heifers were ofered concentrate based diets fortifed with n‑3‑PUFA (PUFA; n = 32) or not (CONT; n = 28) for 30 days prior to breeding at a synchronised oestrous. Following artifcial insemination, heifers were allocated within treatment to either a high or low plane of nutrition. Heifers were maintained on these diets for 16 days following which endometrial tissue was harvested at slaughter for subsequent RNAseq analysis. The infuence of pregnancy status on the endomentrial transcriptome, within each dietary treatment group, was also examined. Post‑insemination diet afected (P < 0.05) the endometrial transcriptome. Specifcally, within n‑3‑PUFA‑supplemented heifers, genes involved in embryonic development and mTOR signalling pathways, important in pregnancy establishment, were identifed as diferentially expressed. Results indicate that dietary supplementation of cattle diets with n‑3‑PUFA may have a positive efect on the expression of key fertility‑related genes and pathways, during the critical window of maternal recognition of pregnancy, particularly where animals are underfed. Reproductive performance is infuenced by many factors, including those available for manipulation through management, such as diet 1 . Supplementing diets with the n-3 polyunsaturated fatty acids (PUFA), eicosapen- taenoic acid (EPA) and docosahexaenoic acid (DHA), has been shown to enhance a range of benefcial traits in cattle, including evidence for improved reproductive status 2 . Optimum proftability within beef herds relies on a compact calving interval, which in turn is reliant on successful establishment and maintenance of pregnancy 3 . Following insemination, the greatest increment of reproductive wastage in cattle is due to early embryonic loss, with approximately 80% of these losses occurring prior to Day 14–16 post-insemination 4 . Maternal recogni- tion of pregnancy is arguably the most critical phase of pregnancy in ruminants, occurring immediately prior to attachment of the conceptus (embryo and associated extraembryonic tissues) to the uterine endometrium 5,6 . Supplementation of cattle diets with n-3 PUFA has been postulated to aid with maternal recognition of preg- nancy and implantation of the conceptus through suppression of uterine secretion of luteolytic prostaglandin F2α (PGF2α), with a number of studies providing evidence for inhibition of uterine PGF2α by EPA and/or DHA, both in vitro and in vivo 7–11 . OPEN 1 Animal and Grassland Research and Innovation Centre, Teagasc, Grange, Dunsany, Co. Meath, Ireland. 2 School of Agriculture and Food Science, University College Dublin, Belfeld, Dublin 4, Ireland. * email: david.kenny@ teagasc.ie