The high incidence of pregnancy loss is a major issue facing the cattle industry. Use of in vitro fertilized (IVF) bovine embryos has become increasingly popular to help alleviate several of these reproductive issues and provide a means to enhance genetic gain for production traits. An uterine paracrine factor cocktail containing epidermal growth factor (EGF), fibroblast growth factor 2 (FGF2), and insulin-like growth factor 1 (IGF1) (collectively termed EFI) was recently identified as a means for improving in vitro derived bovine embryo development and trophectoderm cell numbers. The objectives of this work were to determine if EFI treatment during in vitro bovine embryo culture improves transferable embryo quality and post-transfer placental and fetal development. For each replicate (3 total), slaughterhouse-derived bovine oocytes were matured and fertilized in vitro. At day 4 post-fertilization, ≥8 cell embryos were harvested, pooled, and exposed to either the EFI treatment (10ng/ml EGF, 10ng/ml FGF2, 50ng/ml IGF1) or carrier only (1% Bovine Serum Albumin). At day 7, individual embryos were transferred to estrous synchronized beef cattle. Artificial insemination (AI) was completed on a subset of cows. The EFI treatment increased (P<0.05) the percentage of transferable embryos. Pregnancy rate at day 28 post-estrus was similar among treatments. Circulating concentrations of pregnancy-associated glycoproteins (PAGs) were determined from plasma harvested at day 28, 42 and 56. Transrectal ultrasonography was used to measure fetal crown-rump length (CRL) at day 42 and 56 and to determine fetal sex at day 60. There were no main effect differences observed across days for PAG concentration. Fetus sex by ET/AI group interactions were absent at day 28 but existed at days 42 and 56 (P<0.05). At both days, this interaction reflected fetus sexdependent changes within the ET control group, where PAG concentrations were greater (P<0.05) in male fetuses than female fetuses. No CRL differences or interactions existed among fetal sex and pregnancy group. In summary, addition of the EFI cocktail during bovine embryo culture improved the quality of transferable embryos, but did not affect placental function or embryonic/fetal development. Increasing the numbers of transferable embryos is of value given the cost of in vitro embryo production, but no apparent increases in embryo or placental competency were detected. The EFI treatment increased (P<0.05) the percentage of transferable embryos.

BackgroundEmbryonic and fetal exposure to maternal obesity causes several maladaptive morphological and epigenetic changes in exposed offspring. The timing of these events is unclear, but changes can be observed even after a short exposure to maternal obesity around the time of conception. The hypothesis of this work is that maternal obesity influences the ovine preimplantation conceptus early in pregnancy, and this exposure will affect gene expression in embryonic and extraembryonic tissues.ResultsObese and lean ewe groups were established by overfeeding or normal feeding, respectively. Ewes were then bred to genetically similar rams. Conceptuses were collected at day 14 of gestation. Morphological assessments were made, conceptuses were sexed by genomic PCR analysis, and samples underwent RNA-sequencing analysis. While no obvious morphological differences existed between conceptuses, differentially expressed genes (≥ 2-fold; ≥ 0.2 RPKM; ≤ 0.05 FDR) were detected based on maternal obesity exposure (n = 21). Also, differential effects of maternal obesity were noted on each conceptus sex (n = 347). A large portion of differentially expressed genes were associated with embryogenesis and placental development.ConclusionsFindings reveal that the preimplantation ovine conceptus genome responds to maternal obesity in a sex-dependent manner. The sexual dimorphism in response to the maternal environment coupled with changes in placental gene expression may explain aberrations in phenotype observed in offspring derived from obese females.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-5120-0) contains supplementary material, which is available to authorized users.

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