Hoof Nutrition Intelligence is a twice-a-month web segment that is designed to add to the education of footcare professionals when it comes to effectively feeding the hoof. The goal of this web-exclusive feature is to zero in on specific areas of hoof nutrition and avoid broad-based articles that simply look at the overall equine feeding situation.
Below you will find Part 1 of the latest question and answer installment that you can share with your footcare clients.
Q: Does a lactating mare have higher calcium requirements than the typical mature horse?
By Mieke Holder, PhD
The first recorded use of calcium (Ca), and perhaps unknowingly so, was in the form of limestone and gypsum. Builders and construction workers used compounds in many different applications but, most interestingly, the ancient Egyptians used them in constructing the pyramids.
Doctors later recorded that gypsum was particularly useful in setting broken bones. However, it was only in the 1700s that researchers discovered that Ca was a component of bones themselves.
The majority of the Ca (almost 99%) in a horse’s body is found in bones and teeth. However, Ca also has other important bodily functions. For example, it plays a role in muscle contraction, cell membrane function, blood clotting and some enzymes’ functions, as well. As such, the body must regulate blood Ca concentrations carefully. To do so, bone can act as a storage pool for extra Ca, but it is always best if a horse’s diet provides sufficient Ca.
The National Research Council’s Nutrient Requirements of Horses published in 2007 recommends that a mature idle horse weighing 1,100 pounds should consume 20 grams of Ca daily. This increases to 30 to 40 grams per day for the same horse doing light to heavy exercise.
The Ca requirements for pregnant mares weighing 1,100 pounds increases about midway through pregnancy to 28 grams per day while topping out at 36 grams per day towards the end of pregnancy.
Early lactating broodmares have the highest Ca intake recommendations, starting at 59 grams per day for a 1,100-pound horse and then tapering off throughout lactation. Growing horses have high Ca requirements to support growth and bone health as well.
Forages typically contain higher Ca levels than grains. However, legumes (such as alfalfa) typically contain more than twice the amount of Ca than grass forages. Although grass forages might be sufficient to meet some horses’ Ca requirements (such as idle mature horses), alfalfa hay will generally provide more Ca and more closely meet a growing horses’ higher Ca needs than a grass forage.
Commercial concentrates often include a Ca supplement. Calcium can be added to a concentrate feed as either an organic (such as a calcium amino acid proteinate) or inorganic (such as a calcium chloride or calcium carbonate) form.
When feeding a commercial feed based on the manufacturer’s instructions along with forage, your horse’s Ca requirements should be met. Contact an equine nutritionist or veterinarian if you have any questions regarding your horse’s Ca intake.
Mieke Holder is an assistant research professor within the University of Kentucky’s Department of Animal and Food Sciences.
Hoof Nutrition Intelligence is brought to you by W.F. Young Co. (Absorbine). 
Like many significant achievements, Absorbine® grew out of humble beginnings—and through the tenacity of someone willing to question the status quo. In this case, it was a young woman in late 19th-century Massachusetts: Mary Ida Young. Her husband, Wilbur Fenelon Young, was an enterprising piano deliveryman who relied on the couple’s team of horses to make deliveries throughout the Northeast. Inspired by Mary Ida and Wilbur’s vision, Absorbine® has continued to add innovative products throughout the years — products used every day by horse owners around the world. Which is why, since 1892, we’ve been The Horse World’s Most Trusted Name®.
Click here to read Part 2 of the Nov. 15, 2018 installment: Will adding biotin to my horse’s ration take care of what the farrier calls a poor-quality hoof concern?
Click here to read more installments of Hoof Nutrition Intelligence.