It’s on the Horse Feed Tag – Part 5
Guaranteed analysis of minerals and vitamins
Macrominerals (calcium and phosphorus), microminerals (copper, zinc, and selenium), and vitamin A are required to be listed in the GA. They are all important to your horse’s wellbeing.
Minerals and vitamins are added to commercial feeds because their content varies considerably between different types of forages (hay and pasture). Seasonal and geographical differences also affect the forage’s nutrient profile.
When reviewing the guaranteed analysis for mineral and vitamin content, remember: more isn’t always better. Minerals and vitamins need to be feed at proper levels, and in some cases in specific ratios. Concentrates are formulated to meet a horse’s needs at specific ages or stages of life. Some feeds are formulated to contain minerals and vitamins that complement specific types of forages, such as alfalfa hay or grass hay. This will be listed on the label.
Calcium and phosphorus
Known as macrominerals, calcium and phosphorus are critical to proper bone development and maintenance. Providing calcium and phosphorus in the correct ratio ensures that nutrients interact properly in the horse’s body.
Young growing horses, and pregnant and lactating mares require two parts calcium for every one part of phosphorus found in the total diet. This is expressed as a 2:1 ratio.
In mature horses, the calcium-to-phosphorus ratio needs to be at least 1.1:1. A properly formulated concentrate will include calcium and phosphorus at the ratio and in the amounts needed to meet the specific nutritional requirements of a particular class of horse. (Learn more about calcium and phosphorus in the following KPP Nutritional Minutes: Mighty Minerals and The Ratio of Calcium to Phosphorus Is Important in Your Horse’s Diet.)
Copper, zinc, and selenium
Often referred to as microminerals because they are needed in such small amounts, copper, zinc, and selenium are listed on the GA in parts per million, or ppm.
If you think of 1 ppm as being 1 pound in a million pounds, it gives you some idea of how small an amount it really is.
Copper and zinc play an integral role in normal growth of bone and joint development. Growing horses and breeding mares will require higher amounts of copper and zinc than a mature gelding will. Too much, or too little, of either mineral can cause developmental problems to arise.
Selenium, in concert with vitamin E, is an important antioxidant. Selenium and vitamin E protect cell membranes from damaging free radicals that naturally occur in the horse’s body. Selenium is linked to the immune, reproductive and neuromuscular systems. Selenium levels vary greatly in the soil and water from one region to another. Selenium can be toxic when overfed, so it is important to always know how much selenium is being provided by your horse’s entire diet. (Learn more about selenium in the following KPP Nutritional Minutes: Selenium, an Essential Mineral and Selenium: How Much Is in Your Horse’s Diet?)
Vitamin A is the only vitamin required to be listed on the GA. This is because it is required in larger amounts than the other vitamins. The best source of vitamin A, (derived from beta carotene) is fresh green grass. Nutritionists add vitamin A to concentrates because grass is not always available to horses.
Though not required, other vitamins are often listed on the GA. Vitamin E is an essential vitamin because a horse cannot synthesis it; it must be provided in the feed. Recent research has revealed that vitamin E is a powerful antioxidant that protects nerve and muscle cells. It also supports a robust immune system.
Like vitamin A, the best source of vitamin E is fresh grass. More and more nutritionists find supplemental vitamin E beneficial for horses, especially those that are not grazing or those living on winter pasture. Depending on what class of horse a feed has been developed to nourish, different concentrates will contain different types and levels of vitamins. (Learn more about what vitamins your horse might need in the following KPP Nutritional Minute: Does Your Horse Need Extra Vitamins? Maybe…)
It is very important to realize that concentrates are formulated to provide minerals and vitamins at certain levels and ratios when fed in specific amounts. If you underfeed a concentrate, or cut it with a straight grain like oats, then you are altering the fortification level your horse is receiving and you may no longer be providing the optimal level of nutrition to your horse.
While the GA gives you insight into what nutrients are found in a concentrate, the list of ingredients offers clues into the quality of the feed. Check out part 6 of the “It’s on the Feed Tag” series and learn more about the ingredients found on your horse’s feed tag.
Thank you for your comment.
A horse’s calcium and phosphorus requirements vary depending on age and use. I am unable to find references in the scientific literature that state the optimal Ca:P ratio is 1.5: 1.0 ; however it is an appropriate ratio for mature horses. Nutritionist suggest a 2:1 ratio for growing horses.
According to the 2007 NRC, Ca:P ratios should range from 1:1 to 3:1 (up to 6:1) in horse diets.
Take home message:
Horse owners should always remember that a horse needs at least as much calcium in his diet as phosphorus. If more phosphorus than calcium is fed, problems will occur. If you have questions about the amount of calcium and phosphorus in your horse’s diet consult with a trained nutritionist or speak with your veterinarian.
[…] proper ratio of Calcium and Phosphorus is necessary for bone development and maintenance. The ideal ratio of these minerals is 1.5:1.0. A […]