Calcium is one of the most abundant minerals in the feeds that livestock normally consume. Because of this, it is one of the hardest minerals to try to get ranchers interested in. Ruminant livestock seldom are deficient in calcium. Even if they are deficient for brief times, animals have the ability to draw calcium from the bones in the body, then replace the calcium when their intake is greater than the requirement.
If deficiencies last for a long time, osteomalacia can result from demineralization of the bones, causing them to become weak and brittle and subject to breakage under stress. So making sure that your livestock receive at least the amount of calcium they need is very important to their health and productivity.
Calcium is involved in bone and teeth development, blood clotting, muscle contractions, nerve impulse transmission, cardiac regulation, and many other body functions. So, it’s a very important mineral to keep up with.
There are many times that calcium is a problem because intake is not in the proper proportion with other minerals. Many years ago researchers determined that for proper metabolism and bone development, calcium should be in a 2:1 ratio with phosphorus. In reality there is an acceptable range that calcium can be in relation to phosphorus of 1.5:1 to 8:1, and no ill effects have been seen.
However, many people feel they have to bring calcium and phosphorus to a 2:1 ratio. With feedlot rations, where you can control all of the feeds the animals get, that is a very reachable goal. But when you are dealing with native pastures that can have a ratio of as much as 10:1, adding enough phosphorus to bring that back to a 2:1 ration is nearly impossible, and is definitely not economical.
And not necessary. As I said before, research has shown that as much as an 8:1 ratio was not detrimental to nutrient metabolism or bone development. So as long as you can supplement enough phosphorus to close the native forage ratio to within the 8:1 the livestock will be all right.
Many ranchers will try to get a mineral supplement that is “inverted”. That means the percent of phosphorus is greater than the percent of calcium in it. Inverted minerals work really well to close the ratio but many times the sources of phosphorus needed to make an inverted mineral supplement are not palatable to the livestock, and consumption may be less than what is needed to meet the phosphorus requirement.
The most important thing with mineral supplementation is for the livestock to eat it. A good 1:1 ratio mineral supplement, if consumed properly, will close the ratio to an acceptable range. So don’t get too hung up on only using an inverted mineral supplement.
The biggest problem with calcium comes in the few situations where there is a less than 1.5:1 ratio of calcium to phosphorus. One of these is when livestock are grazing small grain fields, like wheat, oats, rye, and barley. Calcium and phosphorus in small grain forages are many times close to a 1:1 ratio.
When the ratio falls below the 1.5:1 ratio, abnormal bone growth can occur in young animals. The first symptoms will be enlarged joints, tender ankles, and stiffness in the legs.
So, if you graze small grain fields, especially with young animals, you need to have a mineral supplement out with a high level of calcium and little or no, phosphorus. My preference is for a small grain pasture mineral to have around 20% calcium and no more than 4% phosphorus to help widen the ratio of these two minerals. You also need a pretty high level of magnesium in a small grain mineral supplement as the relationship of calcium and magnesium to potassium is a factor in grass tetany.
Another instance where your livestock may experience a calcium: phosphorus ratio that may be less than 1.5:1 is when you are trying to get a good bit of gain from young livestock by feeding either grain, or a supplement with a lot of grain in it. Grains have a much higher percentage of phosphorus in them than calcium. So if you are feeding a fairly high level of grain, especially with a grass or hybrid Sudan hay, you may get a calcium to phosphorus ratio closer than 1.5:1.
If you are feeding a lot of grain supplement, for sure don’t use an inverted mineral supplement. In fact, you should try to find a mineral with at least a 2:1 calcium to phosphorus ratio.
Remember, just because calcium is seldom a problem, don’t let the few situations when you need it slip up on you and hurt your livestock’s productivity.
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