Reproductive patterns and follicular waves in postpartum lactating versus non-postpartum cycling mares.
Authors: Gastal Eduardo L, Pastorello Marilia, Godoi Daniel B, Gastal Melba O
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Reproductive patterns and follicular waves in postpartum lactating versus non-postpartum cycling mares Gastal et al. (2021) characterised the reproductive dynamics of postpartum lactating mares during the critical period from foaling through to subsequent ovulations, comparing their follicular wave patterns, ovarian activity and endometrial changes against non-pregnant cycling mares. Ultrasonographic monitoring revealed substantial heterogeneity in postpartum mares: whilst some exhibited continuous reproductive activity with short intervals to first ovulation (foal heat), others demonstrated extended periods of ovarian inactivity or complete postpartum anoestrus. A key finding was the significantly greater frequency of minor (non-ovulatory) follicular waves in postpartum lactating mares, with spring parturition, declining body condition score and weight loss each contributing to extended intervals before ovulation—important risk factors for compromised fertility during the critical early breeding season. Endometrial echogenicity was heightened during the postpartum interval and sensitive to seasonal influences, though corpus luteum development proceeded normally in both groups. These detailed physiological observations during the foal heat and subsequent interovulatory intervals provide practitioners with evidence-based context for reproductive management decisions, ultrasound interpretation and intervention timing in mares where conception at the foal heat is desired.
Read the full abstract on PubMed
Practical Takeaways
- •Postpartum reproductive variability is normal: expect diverse patterns including short or long foal heat intervals and possible anestrus; don't assume all mares will cycle predictably after parturition
- •Nutritional and seasonal management matters: mares losing body condition or giving birth in spring will likely have extended postpartum intervals with more follicular waves, so optimize nutrition and condition score before breeding season
- •Endometrial changes during foal heat can complicate breeding: monitor endometrial echotexture during the postpartum period as it influences breeding recommendations and fertility outcomes
Key Findings
- •Postpartum lactating mares display variable reproductive patterns including continuous activity, ovarian inactivity after first ovulation, or complete postpartum anestrus
- •Postpartum lactating mares exhibit significantly greater total numbers of minor follicular waves compared to non-postpartum cycling mares
- •Spring parturition, decreased body condition score, and body weight loss increase minor follicular wave frequency and lengthen partum-ovulation interval in postpartum mares
- •Corpus luteum development and regression patterns are similar between postpartum lactating and non-postpartum cycling mares