Calcium is a necessary component of all living things and is also abundant in non-living things, particularly those that help support life, such as soil and water (Pedersen, 2020). Calcium was first isolated by Sir Humphry Davy in 1808 in London and the name ‘calcium’ is derived from the Latin word ‘calcis’ meaning lime. Calcium is a soft, silvery-white alkaline earth metal in its pure elemental state, but it is never found in this isolated state in nature as it exists instead in compounds such as calcium carbonate (limestone), calcium sulfate (gypsum) and calcium fluoride (fluorite), comprising 3.5% of the earths crust.
Calcium oxide (lime) produces a brilliant, intense light when burnt in an oxyhydrogen flame. In the early 1800s it was used to light the stage in theaters, so actors truly performed ‘in the limelight’ as the saying goes.
Calcium is Essential for Animals
Calcium is the most abundant mineral element found in the animal body. It is an important constituent of bone and teeth where it provides hardness and structural strength (98-99% of the total body calcium is found in the skeleton and teeth). The remainder is found in blood, extra cellular fluid, muscle, and other tissues where it plays a role in enzyme function, mediating vascular contraction and vasodilation, muscle contraction, nerve transmission and glandular secretion (Institute of Medicine (US) Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, 1997). Calcium controls the heartbeat of animals, an increase in calcium causes the heart to beat faster and a reduction will make in beat slower (Ewing, 2007).The coagulation of blood is also reliant on the presence of calcium with the element occurring in the plasma. The plasma of mammals usually contains 80-120 mg of calcium/l, but laying hens contain more than 300-400 mg/l (McDonald, 2011).
Calcium metabolism is one of the most important animal health factors influencing production. When calcium is quickly lost from the body and exceeds intake, acute hypocalcaemia will occur, this condition is often found in dairy cows and can result in loss of nervous and muscle function with the clinical condition known as milk fever. Hypocalcaemia can result when blood calcium levels are low, calcium will be removed from the bones to maintain blood calcium levels. Resorption of calcium is controlled by the action of the parathyroid gland. If animals are fed on a low-calcium diet, the ionic calcium concentration in the extracellular fluid falls, the parathyroid gland is stimulated and the hormone produced causes resorption of bone, liberating calcium to meet the requirements of the animal. Since calcium is combined with phosphorus in bone, the phosphorus is also liberated and excreted by the animal (McDonald, 2011).
Absorption of calcium occurs throughout most of the intestinal tract, however absorption can be adversely affected by an imbalance with phosphorus, high fat levels, vitamin D deficiency, the presence of oxalic acid (1% of oxalate can reduce the absorption of calcium by 1/3 in horses) and phytic acid (phytates reduce the availability of calcium from concentrate feed sources in non-ruminants).
Calcium works in synergy with other nutrients. Calcium and phosphorus work together to maintain the health of bones and teeth, with an ideal dietary calcium to phosphorus ratio being 2:1 (this is approximately the ratio in bone). If there is more phosphorus in the diet than calcium this will adversely affect calcium absorption. Calcium and magnesium also work together for the health of the heart, circulation and muscle function. In addition, vitamin D is required for calcium absorption.
What Does Calcium Deficiency Look Like in Animals?
If calcium is deficient in the diet a number of conditions may result:
- Rickets
- Osteomalacia
- Osteoporosis
- Reduced and depraved appetite
- Reduced fertility
- Growth retardation
- Hump-back syndrome in sows
- Thin shells, poor hatchability, reduced egg production, poor egg quality and leg problems in poultry
- Bighead in horses
- Reduced milk production
- Hypocalcaemia (Milk fever)
Milk Fever or parturient paresis is a condition that most commonly occurs in dairy cows 1-2 days prior to calving, but most commonly at the start of lactation. This is due to the temporary imbalance of calcium availability and high calcium demand at the onset of lactation. Milk fever is characterized by a lowering of the serum calcium level, resulting in muscular spasms and, in extreme cases, paralysis and unconsciousness.
The Importance of Calcium for Soil and Plants
Similarly, to animals, having adequate calcium is vital for plant growth. Most of the mineral is located in the leaves where it is permanently fixed in cell walls. It is required for various structural roles in the cell wall and membranes (Marschner, 1995) and thus contributes to the structure of cells and the upholding of physical barriers against pathogens (Thor, 2021). Because of this structural role, plants deficient in calcium have been shown to be more susceptible to pathogens and additional calcium supply in turn has been shown to improve the plant’s resistance. Besides its structural role, the main function of calcium lies in its ability to serve as a second messenger in a variety of processes ranging from root or pollen tube growth and fertilization to responses to abiotic (non-living physical and chemical) as well as biotic (living organisms – viruses, insects etc.) stress (Thor, 2021).
In addition to its roles as one of the macronutrients in plant nutrition, sufficient calcium has a role in maintaining soil physical properties, and in reclaiming sodic soils (Norton, 2021). Soils that are low in calcium usually have associated adverse conditions such as low pH, high aluminium and manganese. Soils with adequate amounts of calcium are often more friable and have superior water infiltration properties because calcium displaces sodium in the soil. Soils that have high sodium and low calcium become sodic and do not allow for good water infiltration.
Calcium from the soil is taken up behind the root tip of the plant and moves primarily in the transpiration stream up from the roots. Once inside the plant, calcium is mostly present in cell walls and therefore, it is not readily remobilized from one part of the plant to another. Plant organs that have low transpiration such as fruits like melons, apples and tomatoes with a waxy skin, or the inner/sheltered parts of leafy plants like lettuce, can develop low calcium disorders (Norton, 2021).
What Does Calcium Deficient Country Look Like in Plants?
Although calcium deficiency in plants is rare, some specific symptoms and effects of deficiency are outlined by (Glendinning, 1990):
- Stunted root system
- Empty shells in peanuts
- Leaves of grasses do not open properly (tips are stuck to the next lower leaf).
- Cavity spot in carrots
- Blossom-end rot (a blackening of the flower-end of fruit) in tomato and capsicum crops.
- Black heart in celery
- “Bitter pit” in apples
- Internal browning in brussels sprouts.
How AgSolutions Can Help
An adequate supply of calcium is essential for both plant and animal health. A good place to start in order to determine the calcium status of your land is by getting a soil test done. AgSolutions can assist your operation by taking a soil test and working with you to develop a soil management program. The NatraMin range including NatraMin Cal-S, NatraMin Hi-Phos and NatraMin Cal-K is formulated to restore bio-activated broad spectrum minerals to your soil, assisting to improve the three aspects of soil fertility – nutritional, biological and structural.
MegaMin Livestock Supplements have a number of blends suitable to assist in providing stock with extra dietary calcium along with other essential macro and trace minerals, which in turn can help to promote production and get a return on investment. Look for MegaMin Extra Phos 8, MegaMin USDA/NOP Extra Phosphorus Blend and MegaMin Bone Defender at your preferred rural store.
For further information on AgSolutions products contact Head Office on 1800 81 57 57.
By Shannon Godwin (BAppSc GDTL)