Effect of maternal nutrition on embryo survival, uterine environment and embryo transfer in sheep

BRUNO GALARRAGA MACARENA; BONADEO; CRISTINA; ALVAREZ; FERNANDEZ J; GIBBONS A,; DE LA SOTA, L; CUETO MARCELA; LACAU, I.M.

Foz Iguazu

Simposio; International Ruminant Reproduction Symposium; 2018

SBTE

Maternal nutrition is an important factor that influences the processes of implantation and embryonicdevelopment. The objective of this study was to evaluate the effect of nutritional status of donor andrecipient ewes on embryo survival and uterine gene expression. The study was carried out in theLaboratory of Small Ruminants Reproduction of INTA Bariloche during the breeding season. Merinodonor (n = 36) and recipient (n = 75) ewes were randomly assigned to two treatment diets, receiving 1.5(Supplemented, [S]) or 0.5 (Restricted, [R]) times daily maintenance requirements during 21 days beforerecovery and transfer of embryos. Estrous synchronization was performed with intravaginal spongescontaining progesterone for 14 days and an i.m administration of equine chorionic gonadotropin (eCG) attime of sponge removal. Donor ewes received a superovulatory treatment, which consisted of theadministration of 100 mg of follicle stimulating hormone (FSH) in 6 decreasing doses every 12 hours.Intrauterine artificial insemination with frozen semen (100 million spermatozoa) was performed 12 hoursafter detection of estrus. On day 7 post-estrus, embryos were recovered and evaluated from S and Rdonors and were transferred by semi-laparoscopy procedure to S and R recipients, defining the followinggroups: SS, SR, RS and RR. Embryo survival rate was determined by ultrasonography on day 22 postembryo transfer. At embryo recovery, endometrial tissue was collected for biopsy from donors (n = 26)and recipients (n = 10) and stored in liquid N2 until analysis. The embryo survival rate was analyzed usingthe CATMOD procedure of SAS. Two-way ANOVA, followed by post- hoc Tuckey tests, was performedto compare relative mRNA expressions. Data are presented as least square means ± pooled standarderrors. Means were considered different when P ≤ 0.05, and tendency to differ when P < 0.10. The uterinegene expression of the receptors for progesterone (PR), insulin-like growth factor 1 (IGF-1R) and leptin(LEPR) was determined by real-time PCR. At the time of embryo transfer, R donors (0.14 ± 0.06) and Rrecipients (0.08 ± 0.03) had less (P < 0.05) uterine relative mRNA levels for PR compared with S donors(0.39 ± 0.15) and S recipients (0.86 ± 0.0). Likewise, IGF-1R and LEPR relative mRNA levels on day 7post-estrus were greater (P < 0,05) in S (IGF-1R: 0.15 ± 0.03; LEPR: 0.17 ± 0.04) than in R (IGF-1R:0.05 ± 0.01; LEPR: 0.04 ± 0.01) females. The embryo survival rate after transfer tended (P < 0.10) to beless in R recipients that received embryos from S donors (SR, 27%) compared with the other treatments(64, 64 and 57% for SS, RS and RR, respectively). In conclusion, nutritional status of donors andrecipients during 21 days before embryo transfer affected uterine gene expression, which might havemodified the uterine environment of both donor and recipient females leading to changes in embryosurvival. Funded by Projects PNSA 1115053 and PRET 1281102 (INTA), PICT 2012-2238 (FONCyT).