⑴．Inorganic calcium sources like calcium carbonate, calcium phosphate and calcium oxide, or other machine processed animal bones, have high content of calcium, but need to be absorbed with involvement of gastric acid. So inorganic calcium is usually used for adult animals with fully developed digestive systems.

(2). Organic calcium sources like calcium formate, calcium gluconate, calcium lactose, calcium citrate and calcium acetate, can be absorbed easily and don’t need involvement of gastric acid during dissolving. Calcium formate is neutral, contains high calcium, can be dissolved and absorbed easily, contains few heavy metals and cost reasonable.

 

• The five kinds of calcium additives used in piglet daily diet

1. Calcium carbonate, is the most commonly used kind in feed industry. It has high content of calcium and cheap price. But it has strong alkalinity, high stimulation to gastrointestinal tract, needs much gastric acid to neutralize during absorption, low absorption rate, contains high heavy metals, has bad palatability for animals. Also it is easy to react with vitamins added into feed, thus lower the absorption rate of vitamins. So it is not suitable for young animals and the ones lack of gastric acid.
2. Calcium lactose, can be dissolved easily, but contains low calcium. It can be made into preparations like calcium lactose and calcium glucose. It needs a large quantity added into animal feed to reach the calcium content 0.58~0.8%, so the cost cannot be accepted for feed industry.
3. Calcium phosphate, is a normal kind in feed additive. It contains 23.3% of calcium, higher than many other kinds. But the calcium is difficult to be absorbed and the high content of phosphors can cause damage to renal function. So it is rarely used in feed additive, especially for aquaculture, for aquatic animals consumed calcium phosphate die easily during transportation.
4. Calcium citrate, contains 21.1% of calcium and has good water solubility, the bioavilability is higher than calcium phosphate. The absorption doesn’t need involvement of gastric acid. But the price is high and mostly used in human medicine.
5. Calcium formate, known as calcium formate feed grade, contains 31% of calcium and 69% of formic acid. It contains low moisture, good water solubility and neutral pH. Adding calcium formate into animal feed can’t cause loss of vitamins and the formic acid decomposed from calcium formate can lower pH in stomach. It has high melting point and only decompose at above 400 degree C. It is the best choice for calcium additive for feed.

 

The standards for selecting calcium sources for piglet feed additives:

1). High content of calcium and neutral pH is best.

2). Good water solubility and few insoluble matters.

3). Low dietary buffer capacity and high absorption rate.

4). Good bioavailability.

5). Low content of heavy metals, no effect on feed quality and flavor,  and harmless to human or animals.

6). Cost reasonable.

7). Particle uniform, free flowing and easy to mix.