Can We Improve a Breed Through Nutrition?

Let’s talk about the importance of feeding the broodmare, not only for her health and her baby’s well-being, but for the future of the breed.

We all know nutrition is important, but I don’t think many of us realize just how important it is early on in life. Good forage and mineral supplementation for pregnant mares goes much, much further than simply helping her to grow a healthy foal. In this short write up, I want to briefly explore epigenetics & fetal programming, and how they might play a role, good or bad, in the future of the Kiger horse.

First let me explain what I mean by “epigenetics” and “fetal programming”.

Epigenetics is the study of small changes in gene expression caused by environmental stimuli. Many nutrients have been studied in this area and have shown to change how certain genetic traits are expressed in an individual, especially in relation to maternal nutrition on the developing fetus.

Fetal programming is the concept that during certain critical periods of fetal growth, external stimuli can create permanent structural, physiological and metabolic changes. Nutrition is thought to play a large role in these changes, both good and bad. Psychological stress on the mare also affects the fetus’ long term health and can alter the temperament of the foal.

Over-feeding a mare can lead to health defects in the foal that will affect him later in life. Similarly, mares that do not consume enough calories during pregnancy can produce foals that are more prone to metabolic disease and other issues. One study also found that when mares were under psychological stress during pregnancy it resulted in higher rates of insulin resistance in their foals. The mare’s body is telling the fetus that food is scarce and danger is lurking, so his body should be prepared to make good use of the food that is available once he is born. This is an important factor to consider when we’re talking about mustangs. If there is a hard winter on the HMA and mares do not receive enough nutrition, their foals could potentially be more prone to disease later in life, especially if we take that foal and put him into an environment that is different to the one that his dam was in during pregnancy. A common complaint about Kigers is that some gain weight very easily and could be insulin resistant, which can be hard to manage when lush green grass is all around. Epigenetics could potentially limit this issue in future generations.

Fetal programming suggests that there are periods in fetal development that are more critical than others. During these critical periods, the fetus is more impressionable to stimuli such as excess or depleted nutrition. One of these critical periods is thought to be during the 3rd trimester. Feeding the mare appropriately during this time not only sets up the foal for their future, but it is also during this time when the mare begins the production of colostrum. Adequate nutrition and mineral during this time allows the mare to produce higher quality colostrum for her foal. However, over-feeding the mare a diet of high starch in her 3rd trimester can actually diminish colostrum production, so it is important to find the right balance.

Although my Kiger breeding program is small, I am fortunate to have a good size cow-calf operation where I can compare some of these theories, since the same applies to all mammals. Genetic selection in our cattle herd is our first priority (the genetic potential has to exist before it can be expressed), and nutrition is a close second. One of the main determining factors for large, healthy calves is milk production in the cow. I’ve seen pregnant cows that when fed a diet of poor quality forage, produced poor quality calves that failed to thrive, even when the cow was fed an ample amount, supplemented with minerals, protein and vaccinated. Those same cows when fed a diet of high quality forage the following year have produced some of the best calves I’ve seen. The high quality forage allowed the cows to produce healthier calves, more milk and better quality colostrum than the previous year. This in turn resulted in fewer difficult births, fewer calf deaths and larger calf growth over the same amount of time. Healthier female calves reach maturity sooner, are in better condition to conceive and raise better calves by putting more energy into milk production since their early growth needs have been met. I mention all this to say that feeding supplements alone is of little to no value if your forage quality is poor. There is no magic supplement that can give you larger foals or better performing animals. And although the third trimester is important for a variety of traits, do not neglect the first two trimesters or the open mare before breeding. Mares and cows that are healthier will conceive easier and these benefits will pass down throughout the generations.

Providing high quality mineral and forage for the mare’s diet not only helps the fetus develop but could potentially be helping her foal’s future offspring as well. Studies have shown that epigenetic changes during fetal development not only affect that foal directly but can affect future generations. Malnutrition causes impaired growth of the fetus and its organs, long-term impaired organ function, as well as musculoskeletal impairment and poor performance. As breeders who are working to develop a relatively new and rare breed, we need to keep this in mind for several reasons. A Kiger breeder may not see the true genetic potential of their horses until several generations of offspring are raised and fed appropriate nutrition. Mature mares coming off the HMA almost always out produce themselves when fed adequately, throwing foals that are taller than one or both parents. If we consider that the effect of epigenetics appears not only in the offspring of the wild mare, but also her foal’s future offspring, then we may not see the true genetic potential of a wild bloodline for 2-3 generations in captivity. It’s important to remember, epigenetics does not alter the DNA, but it “turns on” the expression of already present genes when the environment is favorable. It can also “turn off” these same genes when the environment is poor. Kigers in the wild tend to be around 14h-15.2h, which is where the breed standard for height was derived. However, it is not uncommon to see domestic born Kigers reach 16h, even if their parents were in the 15h range. This does not mean that domestic breeders are changing the breed, but that nutritional epigenetics are at play. Genetic expression is changing because the environment in which the fetus is being raised is changing. A taller horse is not the only change we may see. With proper nutrition and a low stress environment for the mare, we could see a future of the breed that is healthier, more athletic and easier to train. Kigers already have genetics that have allowed them to survive in tough conditions, imagine their potential to thrive when conditions are nearly perfect.

Kaitlin Knox Winterwind Kigers


Choi, S. and Friso, S., 2010. Epigenetics: A New Bridge between Nutrition and Health. Advances in Nutrition, 1(1), pp.8-16.

Coverdale, J., Hammer, C. and Walter, K., 2015. HORSE SPECIES SYMPOSIUM: Nutritional programming and the impact on mare and foal performance1. Journal of Animal Science, 93(7), pp.3261-3267.

Kwon, E. and Kim, Y., 2017. What is fetal programming?: a lifetime health is under the control of in utero health. Obstetrics & Gynecology Science, 60(6), p.506.

Reynolds, L. and Caton, J., 2012. Role of the pre- and post-natal environment in developmental programming of health and productivity. Molecular and Cellular Endocrinology, 354(1-2), pp.54-59.

Satterfield, M., Coverdale, J. and Wu, G., 2010. Review Of Fetal Programming: Implications To Horse Health. [online] Available at: <> [Accessed 27 September 2020].

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