Horses are long day seasonal breeders, with both males and females showing seasonal variability in reproductive function, but it is much more obvious for the mares. Most mares have suppressed ovarian activity which begins in the fall and ends in early spring, but they do not immediately begin normal cycles. The interval between normal cycling and cessation of cycling is called the transition period and lasts approximately 6 to 10 weeks.
Here in the continental United States, the transition period usually begins between March and April but may be delayed by older age, low body weight, very cold weather or poor nutrition. An increasing plane of nutrition, such as grazing spring pastures, seems to hasten cycling and fertility.
During the transition period there will be 2 to 5 "waves" of developing follicles which are either resorbed or remain as large follicles which fail to ovulate. Most mares show no outward sign of cycling or receptivity to the stallion during the transition phase. Others may show estrus, but at irregular intervals that are either longer or shorter than normal.
There is really no treatment available or necessary for the transition period in most mares. If you would like to breed your mare, an experienced reproductive veterinarian will be able to follow the follicles by palpation and/or ultrasound to know when your mare is truly ovulating and ready to be bred.
Mares that typically show wide swings in behavior with their cycles will begin to show this pattern during the transition period. It may even be exaggerated when follicles reach a large size, but fail to ovulate (anovulatory).
Some mares with metabolic syndrome have the most difficulty of all. The large anovulatory follicles can cause severe colicy pain. Insulin may rise and is not controlled well by diet. Crests typically enlarge and harden at the same time. Some mares have mammary development and may lactate. The mare can even progress to becoming laminitic.
Tincture of time will resolve any transition period issues for most mares. However, when irregular cycling, pain, behavior swings and anovulatory follicles persist, Vitex agnus-castus can help support the natural transition to a normal hormonal balance.
Vitex agnus-castus (Chastetree, Chasteberry) fruits/berries act like adaptogens for the reproductive system, helping the mare's body maintain normal function in both the brain and the ovaries. Unlike common hormonal drugs, it does not interfere with function, but assists her to progress to natural, balanced activity. Studies have shown Chasteberry extracts help maintain normal levels of dopamine and the hormones LH and FSH.
The transition period is a temporary interval of disarray during which the mare's hormones progress to a more orderly normal cycle. Mares that remain highly symptomatic or do not appear to be leveling out can be helped to achieve homeostasis with Vitex agnus-castus. Using a 5X extract allows you to feed a much smaller volume. Most average size horses will respond to a dose of 3 to 6 grams.
Uckele Health & Nutrition, maker of CocoSoya®, offers supplements that mares during cycling and breeding.
Chasteberry Extract 5X. Chastetree berries, or simply Chasteberry - have a long traditional history of use to help balance hormonal systems. CB extract functions as an adaptogen in these hormone systems. Adaptogens are substances that assist in stabilizing physiology and promoting homeostasis. Homeostasis is a state of equilibrium in which the organism functions optimally.
Glycocemic EQ supports blood sugar levels within normal ranges. Targeted ingredients also promote balanced immune and thyroid function, normal glucose metabolism, healthy nerve function, and proper insulin sensitivity. Promotes healthy insulin levels by providing nutrient levels that are compatible with a wide variety of diets and sources of hay.
LaminOX provides full spectrum support for hoof health and comfort, healthy circulation and metabolic balance. Supports healthy vascular function with Jiaogulan to promote circulation and structural hoof health. Contains the amino acid Arginine, a precursor to nitric oxide, which also plays an important role in healthy blood flow.
About Dr. Kellon
Dr. Eleanor Kellon, staff veterinary specialist for Uckele Health & Nutrition, is an established authority in the field of equine nutrition for over 30 years, and a founding member and leader of the Equine Cushings and Insulin Resistance (ECIR) group, whose mission is to improve the welfare of horses with metabolic disorders via integration of research and real-life clinical experience. Prevention of laminitis is the ultimate goal. www.ecirhorse.org
Uckele Health & Nutrition, maker of CocoSoya, is an innovation-driven health company committed to making people and their animals healthier. On the leading edge of nutritional science and technology for over 50 years, Uckele formulates and manufactures a full spectrum of quality nutritional supplements incorporating the latest nutritional advances. www.uckele.com.
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