Impact of Equine and Bovine Oocyte Maturation in Follicular Fluid From Young and Old Mares on Embryo Production in Vitro.
Authors: Spacek Sheila G, Carnevale Elaine M
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Follicular fluid bathes the developing oocyte and contains signalling molecules from surrounding cells that influence both maturation capacity and embryonic potential, yet little is known about whether this microenvironment differs meaningfully between young and aged mares. Spacek and Carnevale (2018) investigated this question by collecting follicular fluid from dominant follicles in young mares (4–13 years) and old mares (21–26 years)—both before and after ovulation induction—then using it to mature equine and bovine oocytes in vitro before assessing fertilisation and early development outcomes. Contrary to expectations, equine oocytes actually tended to produce more blastocysts when matured in aged mare follicular fluid (P = 0.08), whilst bovine oocytes showed higher cleavage rates in young mare fluid (P = 0.001), suggesting that age-related changes in follicular fluid composition do not uniformly impair oocyte competence. These findings complicate the narrative around reproductive ageing in mares and warrant further investigation into the specific biochemical factors driving these species-dependent responses, particularly given the implications for assisted reproduction programmes and breeding management decisions in older mares.
Read the full abstract on PubMed
Practical Takeaways
- •Age-related changes in follicular fluid composition do not uniformly impair oocyte quality; species-specific responses differ between equine and bovine models
- •Older mares may retain reproductive capacity through compensatory mechanisms in follicular microenvironment despite advancing age
- •Further research needed before age alone should be considered a contraindication for assisted reproductive technologies in aging mares
Key Findings
- •Equine oocytes matured in follicular fluid from old mares (21-26 years) tended to produce more blastocysts (P = 0.08) compared to those matured in fluid from young mares (4-13 years)
- •Bovine oocyte cleavage rates were significantly higher (P = 0.001) when matured in follicular fluid from young mares compared to old mares
- •No conclusive evidence that follicular fluid from aged mares has deleterious effects on oocyte maturation or early developmental potential