Does breeding with 2 doses result in more post-breeding fluid accumulation and cause decreased fertility?
The numerous reports on timed-insemination protocols demonstrate that multiple inseminations in normal mares are not harmful. Insemination with frozen-thawed semen twice per cycle does not increase the incidence of fluid accumulation and post-breeding endometritis. Moreover, data from several large scale studies suggest that multiple inseminations on a cycle (fresh or frozen) result in higher pregnancy rates, presumably because of a decrease in the interval between insemination and ovulation. All mares experience a natural inflammatory response within the uterus, after the deposition of semen. The post-breeding inflammation, initiated by the first insemination is cleared within 12 hours in reproductively healthy mares. Thus, a second insemination can safely be performed within 24 hours, without negatively affecting fertility. Some problem mares appear less efficient at clearing the uterine lumen of semen and inflammatory products accumulated after breeding. Fertility is reduced in this
