by Emily Dickson

The Nutritionist’s Guide To Putting Mares Under Lights

The Nutritionist’s Guide To Putting Mares Under Lights

Every breeding farm knows the benefits of early foals. Of course, you want to optimize your mare’s cycle so that your foals have the best chance of developing, performing and competing against foals of the same age, thanks to that universal January 1st horse birthday date.

Planning for healthy foals always starts with improving the health of your broodmares, so let’s discuss how to best support your broodmares this time of year as you implement lighting programs.  

A Quick Recap of Your Mare’s Cycle

Mares are seasonally polyestrus, meaning that they have regular estrus (or heat) cycles during late spring, summer and fall, but do not experience estrus during the winter (also known as the anestrus phase). 

The seasonal reproductive cycle was important for the horse’s evolution because a mare that conceives in the spring or summer, with an average 330 day gestation period, would foal in mild conditions and offer the best chance of survival. 

On the modern breeding farm, this is much less of a concern. 

Without interference, mares will normally begin cycling (and be receptive to a stallion) starting in March and stop cycling in September.

As you know, the use of artificial lighting for mares has become common practice and with December 1st upon us, your mares may already be under lights.

Why Use Lighting Programs For Mares? 

The mare’s cycle is controlled by hormones and those hormones are impacted by external factors, such as length of day, temperature and nutrition.

The pineal gland is a small, egg-shaped gland located in the center of the brain between the two hemispheres. This small but mighty gland processes the amount of light and produces melatonin in response. 

Melatonin plays a hugely important role in adjusting the body’s circadian rhythms according to season and it also tells mares whether or not it is the correct season for reproduction. In horses, melatonin is primarily made during hours of darkness and inhibited by light.

When there are many hours of darkness (hello, winter), melatonin is produced for longer periods of time and suppresses gonadotropin releasing hormone (GnRH), which is the first domino in the cascade of hormones that control equine reproduction

So artificial lighting for breeding comes into play! By putting mares under lights for around 8 weeks prior to optimal breeding (around February 1st, which will have a foal close to January 1st of the following year), we can alter the levels of melatonin that are secreted and therefore “turn on” GnRH, which will begin to stimulate the mare’s ovaries and reproductive status.

How is Nutrition Related? 

While lights will stimulate a mare to cycle through the manipulation of daylight hours, nutrition is the next greatest factor related to reproductive success. 

A mare in poor nutritional status, or low body condition, will start cycling later even if she is placed under lights at the appropriate time.  

Once she starts cycling, it will often take more breedings and multiple cycles to achieve a successful pregnancy. This is an obvious concern related to reproductive health and efficiency, but also shifts foaling dates later, ultimately negating the work and cost associated with placing a mare under lights early in the season.  

Additionally, during early pregnancy, the horse immune system undergoes extensive changes to protect the mother and fetus throughout the various developmental stages. It is well established that the gastrointestinal system houses approximately 70% of the horse’s immune system and function.  

Therefore, supporting the immune system through the GI tract can have whole-body effects to potentially improve pre-pregnancy and early pregnancy outcomes.  

How You Can Support Your Mare’s Nutrition Program

Research has repeatedly shown us that a stable and healthy gut microbiome supports normal immune function, aids in nutrient digestion and utilization, and reduces the effects of various stressors.  

Breeding season and late pregnancy are high stress periods.  

During breeding season, mares are handled and extensively monitored for ovulation which increases overall stress. Shortly after confirmation of pregnancy, mares are often moved from their previous herd and housed in stalls with dietary changes often following.  

The increase in handling, changes in herd dynamics, and possible diet changes result in stress that can negatively impact the gut microbiome and may lead to digestive disorders – the very thing that you must avoid to have your broodmares performing at their highest ability.. 

You can help reduce the effects of stress on your mares by protecting the gut microbiome with FullBucket Probiotic Pellets. One scoop a day can help promote normal GI and immune function, which is needed more than ever during breeding season. 

So during lighting season, do not forget that your mare’s nutrition is equally as important. Get your probiotic pellets here today!

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