Relationships between blood and follicular fluid urea nitrogen concentrations and between blood urea nitrogen and embryo survival in mares

Yatta Linhares Boakari, Hossam El-Sheikh Ali, Maria Schnobrich, Kristina Lofrumento, Charlie Scoggin, Etta Bradecamp, Kirsten Scoggin, Alejandro Esteller-Vico, Anthony Claes, Laurie Lawrence, Barry Ball

Research output: Contribution to journalArticlepeer-review

Abstract

High blood urea nitrogen (BUN) concentration is linked to low fertility in cows and ewes; however, this relationship has not been reported in mares. The study characterized the relationship between BUN and follicular fluid urea nitrogen (FUN) during follicle growth (Experiment 1) and the impact of BUN from embryo donors on the pregnancy outcome of recipient mares (Experiment 2). In experiment one, follicular fluid and blood samples were collected from mares during diestrus with growing follicles and during estrus with pre-ovulatory follicles (n = 16 and 10 mares, respectively). In experiment two, BUN concentrations of embryo donors were related to pregnancy outcome after embryo transfer. In experiment one, there was a strong positive correlation between BUN and FUN (R = 0.83; P < 0.0001), with higher BUN in mares with growing follicles than with preovulatory follicles (P = 0.004) and higher FUN in growing follicles than in preovulatory follicles (P = 0.031). In experiment two, BUN was higher in donor mares that produced unsuccessful embryos compared to donor mares that produced embryos resulting in successful pregnancies at D14 (P < 0.03). Additionally, there was an effect of age (P = 0.01) and interaction between age and lactation (P = 0.009) in donor mares for embryo survival after embryo transfer. Donor mares with unsuccessful embryos were older than donor mares with successful embryos. Therefore, these experiments showed that BUN was related to follicular fluid environment as well as to the survival of Day 7–8 embryos after transfer to recipient mares.

Original languageEnglish
Pages (from-to)142-150
Number of pages9
JournalTheriogenology
Volume160
DOIs
StatePublished - Jan 15 2021

Bibliographical note

Funding Information:
This work was funded by Science without Borders- CNPq - GDE- USA [Grant/Award number: 208518/2014–2 ]; USDA -ARS National Program 215, Grass, Forage and Rangelands Agroecosystems [project number 5042-21000-003-00D] and the Albert G. Clay Endowment, at the University of Kentucky.

Funding Information:
This work was funded by Science without Borders- CNPq- GDE- USA [Grant/Award number: 208518/2014–2]; USDA-ARS National Program 215, Grass, Forage and Rangelands Agroecosystems [project number 5042-21000-003-00D] and the Albert G. Clay Endowment, at the University of Kentucky.

Publisher Copyright:
© 2020 Elsevier Inc.

Keywords

  • Embryo survival
  • Equine
  • Follicular fluid
  • High protein diet
  • Pregnancy
  • Urea

ASJC Scopus subject areas

  • Small Animals
  • Food Animals
  • Animal Science and Zoology
  • Equine

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