Calcium (Ca) - cattle
Calcium or lime is an earth alkali mineral.
Calcium in animals
More than 95% of calcium (Ca) in the body is found in the bones. The calcium in bones, as well as in milk, occurs in the form of calcium phosphate (Ca3(PO4)2). Thus, both calcium and phosphorus (P) are required for bone formation and milk production. The ratio of calcium to phosphorus in the ration is therefore of great importance, although in recent years, there has been more emphasis on optimizing/minimizing phosphorus in the ration.
Dairy cows require a large amount of calcium to produce high volumes of milk. The bones provide the largest buffer. Vitamin D, with the help of hormones, regulates the absorption and reabsorption of calcium to and from the bones. As the animal ages, it becomes more difficult to mobilize calcium from the bones, which also increases the risk of milk fever.
In addition, calcium is responsible for the transmission of nerve impulses (and therefore muscle contractions), the production of hormones, blood clotting, pH regulation of the blood, fertility, and the regulation of membrane activities.
| Category | g/kg dry matter | g/animal/day |
|---|---|---|
| Young cattle from 4 months | 5.6 | 22 |
| Young cattle from 9 months | 3.5 | 20 |
| Young cattle from 16 months | 2.8 | 21 |
| Dry 8-3 weeks to calving | 2.4 | 27 |
| Dry 3-0 weeks to calving | 2.8 | 31 |
| Milking (20 kg) | 3.2 | 60 |
| Milking (40 kg) | 4.2 | 100 |
Calcium deficiency
A calcium deficiency can structurally lead to osteoporosis and leg problems. It also increases the risk of milk fever and muscle cramps can also occur. A high magnesium content, through mutual competition, lowers calcium absorption and can thus cause an indirect calcium deficiency. In the diet of dry cows, higher magnesium levels are used to stimulate calcium absorption.
Calcium surplus
Calcium excess is rare because the body has several mechanisms at its disposal to excrete excess calcium. A temporary excess calcium level has no consequences. A prolonged elevated calcium intake through feed can cause kidney problems and lead to the calcification of soft tissues, such as the kidneys, liver and vessel walls. The CVB (2005) gives a toxicity limit of 15g of calcium per kilogram of dry matter (for chronically high levels).