THE cycle of birth has arrived again after our endeavours of last spring to encourage mares to conceive and nurture their healthy pregnancies to fruition.
Your mare has foaled and rewarded you for your patience over the past 11 months, so now the pressure is on to achieve the same goal within the next month.
Assuming that the foaling was normal without a retained afterbirth and the mare is in good health and body condition, your vet will examine post foaling mares around day eight or nine. They will see if her uterus has reduced back in size (uterine involution), if she has any fluid on ultrasound, and if her uterus is clean by taking a cervical swab. They will also assess her birth passage for any damage that may have occurred during the foaling process.
Mares usually begin cycling again six to eight days after foaling – this is known as foal heat. Breeding at foal heat carries only half the chance of a conception as later cycles, so in the thoroughbred world, it is rarely considered until the end of the season is looming and time is running out.
Post breeding management such as flushing as soon as four hours post cover is essential with foal heat matings.
It is preferable if she doesn’t ovulate until at least day 10 post foaling to allow the uterus a better chance of receiving the sperm and expelling the seminal fluids without setting up an inflammatory reaction. Most mares are bred approximately 26-30 days after foaling; this allows the mare time to recover, and affording a better chance of conception and still ensures the mare is bred in time to have a foal around the same time each year.
Mares can be ‘short-cycled’ which means the vet administers a hormone called prostaglandin (PG) around day 20 post foaling to encourage them to return to oestrus sooner than her natural cycle. This doesn’t always work but when it does, it gains about a week of time.
You may have experienced having decided to miss foal heat, that your mare doesn’t appear to be teasing well at the expected 27-29 days after foaling and when the vet examines her at 30-32 days, her ovaries are small with little activity.
This scenario of ‘lactational anoestrus’ is more common around now, early in the season and is most likely due to a lack of exposure to light in the latter days of her pregnancy.
Dry mare barns around the country are beautifully lit up and set on timeclocks but often the pregnant mare barns are sometimes left in the dark. We forget that the pregnant mare also needs to be tricked into thinking that it is spring so that she will foal on time and cycle without fail in the weeks after she has foaled.
If you are thinking of calling the electrician to your barn, LED bulbs are better than fluorescent tubes or the incandescent bulb at helping the mare to cycle as they emit more blue light.
Ironically, it is this blue light emitted by LEDs, mobile phones and laptops that are disrupting human sleep patterns because it affects our melatonin production.
The blue light waves reduce melatonin production having the effect of keeping us awake at bedtime. It is by playing with mares’ melatonin production that we can manipulate their seasonal reproductive cycle.
Catherine Dwan MVB of Cheval Veterinary Clinic is a member of the Equine Group of Veterinary Ireland
TOP TIPS ON HARVESTING AND STORING COLOSTRUM
Successful passive transfer of antibodies from the mare to her foal depends on many factors, including quality and quantity of colostrum, timing of the ingestion of colostrum, health status of the foal, and absorption of antibodies by the small intestine. Assessment of colostrum quality evaluates only one component of the passive transfer process but it can be done by using an inexpensive piece of equipment that is essential to have in your foaling kit – a colostrum refractometer. It can determine the quality of the colostrum produced by your mare, and if it is inadequate, the foal can be supplemented with additional frozen -thawed colostrum of good quality by bottle or stomach tube. Refractometer evaluation of colostrum is also valuable in determining the quality of colostrum to be harvested and stored in a freezer and can test your foal has absorbed the colostrum antibodies by testing the blood from 12 hours of age for adequate IgG levels. A total of 250 to 500mls of colostrum may be harvested from postpartum mares without adversely affecting passive transfer to their own foals. The best colostrum donors are healthy mares that have had one or more foals and that have been vaccinated prior to foaling. Ideally, the colostrum should have a refractometer score of 25% or higher and be tested for the presence of anti-RBC antibodies, to prevent the possibility of neonatal isoerythrolysis or jaundice foal syndrome. Frozen colostrum can be safely stored for up to two years. Your vet will advise you regarding the testing, banking and usage of frozen colostrum.