30/10/2026
This Weeks Mineral in the Spotlight is...
🐴 𝗖𝗔𝗟𝗖𝗜𝗨𝗠: 𝗠𝗢𝗥𝗘 𝗧𝗛𝗔𝗡 𝗝𝗨𝗦𝗧 𝗦𝗧𝗥𝗢𝗡𝗚 𝗕𝗢𝗡𝗘𝗦!
When we think about calcium, we usually think about bones and teeth. But calcium also plays important roles in muscle contraction, nerve function and many other processes throughout the body.
But did you know that not all the calcium your horse eats is necessarily available for their body to use?
For some horses, getting enough available calcium is just as important as getting enough calcium in their feed.
🌱 𝗕𝗨𝗧 𝗛𝗘𝗥𝗘'𝗦 𝗦𝗢𝗠𝗘𝗧𝗛𝗜𝗡𝗚 𝗔𝗨𝗦𝗧𝗥𝗔𝗟𝗜𝗔𝗡 𝗛𝗢𝗥𝗦𝗘 𝗢𝗪𝗡𝗘𝗥𝗦 𝗦𝗛𝗢𝗨𝗟𝗗 𝗞𝗡𝗢𝗪!
Most horses will receive adequate calcium from grass and forage.
However, some common Australian pasture grasses, including Kikuyu, Buffel and Setaria, contain oxalates that bind to calcium in the digestive tract, making it difficult for horses to absorb.
That means a horse can be eating plenty of grass but still struggle to obtain enough usable calcium!
Over time, grazing high-oxalate pastures without adequate calcium can lead to a serious condition called nutritional secondary hyperparathyroidism, commonly known as Big Head Disease.
And in the case of young, growing horses, this may affect skeletal growth and strength.
🦴 𝗡𝗢𝗧 𝗔𝗟𝗟 𝗖𝗔𝗟𝗖𝗜𝗨𝗠 𝗦𝗢𝗨𝗥𝗖𝗘𝗦 𝗔𝗥𝗘 𝗧𝗛𝗘 𝗦𝗔𝗠𝗘!
Different calcium sources vary in solubility and how readily horses can digest and absorb them.
Calcium oxalate, the form bound by oxalates in certain grasses, is poorly available to horses.
Calcium carbonate is cheap and commonly used in supplements to keep the price down but still have “label appeal", but it is relatively insoluble, and its availability can be lower than that of some other calcium sources.
That's why it's important to consider not just how much calcium a supplement contains, but also its source and availability.
Marine calcium, particularly calcium derived from calcified red seaweed, is an interesting option. Research in horses has found encouraging results for its calcium digestibility compared with limestone, although more research is needed.
🔬 𝗖𝗔𝗟𝗖𝗜𝗨𝗠 & 𝗦𝗧𝗢𝗠𝗔𝗖𝗛 𝗔𝗖𝗜𝗗 𝗕𝗨𝗙𝗙𝗘𝗥𝗜𝗡𝗚
Calcium is a popular natural buffer to increase stomach acid pH however the calcium:phosphorus ratio is one of the most important mineral ratios in horse health.
An ideal ration is 1.5:1 and a ratio above 6:1 can interfere with absorption of other minerals. So it is important to control the calcium level to that which can be used safely long term.
A small study in horses found that a specific calcium product increased stomach-fluid pH after feeding. This suggests it may help buffer stomach acid.
This is particularly interesting when considering feeding management around work and travel, when changes to routine, feed intake and stress can affect the horse’s digestive environment.
Depending on the product and feeding directions, a suitable buffering feed like GASTRO GO which contains a highly absorbable form of calcium, given before work or travel is worth considering as part of a broader gut-health management plan.
🤔 𝗪𝗛𝗘𝗡 𝗠𝗜𝗚𝗛𝗧 𝗘𝗫𝗧𝗥𝗔 𝗖𝗔𝗟𝗖𝗜𝗨𝗠 𝗕𝗘 𝗡𝗘𝗘𝗗𝗘𝗗?
✔️ Horses grazing high-oxalate pastures
✔️ Growing horses and breeding mares with increased requirements. However if you are feeding a good quality feed designed with growing and breeding horses in mind. This should have your horse's needs covered.
✔️ Horses whose overall diets don't provide enough calcium or have an imbalanced calcium-to-phosphorus ratio
❤️ 𝗧𝗛𝗘 𝗖𝗮 𝗧𝗔𝗞𝗘𝗔𝗪𝗔𝗬
Calcium is essential — but getting the right amount in a form your horse can use is what matters.
If your horse grazes subtropical pasture, don't assume their grass is meeting all their calcium requirements. Consider the pasture type and the complete diet, and seek professional advice on appropriate supplementation.
The answer isn't to add calcium to every feed. It's to understand what your horse is already receiving and supplement where there's a genuine need.
