Elevated blood urea nitrogen alters the transcriptome of equine embryos

Yatta Linhares Boakari, Hossam El-Sheikh Ali, Pouya DIni, Shavahn Loux, Claudia Barbosa Fernandes, Kirsten Scoggin, Alejandro Esteller-Vico, Laurie Lawrence, Barry Ball

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


High blood urea nitrogen (BUN) in cows and ewes has a negative effect on embryo development; however, no comparable studies have been published in mares. The aims of the present study were to evaluate the effects of high BUN on blastocoele fluid, systemic progesterone and Day 14 equine embryos. When a follicle with a mean (±s.e.m.) diameter of 25 ± 3 mm was detected, mares were administered urea (0.4 g kg-1) with sweet feed and molasses (n = 9) or sweet feed and molasses alone (control; n = 10). Blood samples were collected every other day. Mares were subjected to AI and the day ovulation was detected was designated as Day 0. Embryos were collected on Day 14 (urea-treated, n = 5 embryos; control, n = 7 embryos). There was an increase in systemic BUN in the urea-treated group compared with control (P < 0.05), with no difference in progesterone concentrations. There were no differences between the two groups in embryo recovery or embryo size. Urea concentrations in the blastocoele fluid tended to be higher in the urea-treated mares, with a strong correlation with plasma BUN. However, there was no difference in the osmolality or pH of the blastocoele fluid between the two groups. Differentially expressed genes in Day 14 embryos from urea-treated mares analysed by RNA sequencing were involved in neurological development, urea transport, vascular remodelling and adhesion. In conclusion, oral urea treatment in mares increased BUN and induced transcriptome changes in Day 14 equine embryos of genes important in normal embryo development.

Original languageEnglish
Pages (from-to)1239-1249
Number of pages11
JournalReproduction, fertility, and development
Issue number16
StatePublished - Nov 2020

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  • blastocoele fluid
  • embryo development
  • high-protein diet
  • horse

ASJC Scopus subject areas

  • Biotechnology
  • Reproductive Medicine
  • Animal Science and Zoology
  • Molecular Biology
  • Genetics
  • Endocrinology
  • Developmental Biology


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