Natural grazing (veld) which is actively growing and green, generally requires lower levels of supplementation, with the main limiting nutrient to production being phosphorus and trace minerals.
Cattle grazing pastures with a low soil phosphate status result in insufficient quantities of phosphate being obtained from the grazing (Dixon et al. 2020). The effect of a phosphate deficiency in cattle is noteworthy: reduced appetite, which leads to reduced intake of grazing and hence nutrients.
Fig. 1 below depicts the soil phosphate status of regions within South Africa. A soil phosphate status of <5mg/kg is considered to be deficient in phosphorus, hence supplementation on these grazing will lead to positive results
Figure 1. The soil phosphorus status of areas within South Africa
Phosphate deficiencies
Acute phosphate deficiencies in cattle result in the following symptoms:
- Pica: Chewing of abnormal items such as bones
- Poor body condition score
- Poor growth and development of young stock
- Botulism
Phosphate is used by cattle to develop a strong skeletal system and teeth, plays a role in the metabolism of fat, protein, and carbohydrates, stimulates milk production and improves feed conversion.
The cattle on the farm which have the highest phosphate requirement are young stock for bone and skeletal development, and first calf cows for growth, pregnancy and milk production. Late pregnant animals for foetus development and lactating cattle for milk production. To produce 1L of milk, roughly 1.5g of phosphate is required. Should enough phosphate not be obtained from grazing, cattle mobilise phosphate from the bones to address the deficiency.
Minerals should also be balanced within the diet. The calcium-to-phosphate ratio is of importance, if either calcium or phosphorus is too high, the absorption of the other mineral will be affected. Phosphorus supplementation is only effective if cattle are not deficient in protein and energy.
Research conducted by de Waal et al.(1996) on the Armoedsvlakte in Vryburg demonstrated the benefits of phosphorus supplementation in cattle herds within South Africa. Cows that received phosphate supplements throughout the year, weighed 33kg more than those which received phosphate supplementation during one season. The summary of results is provided in Table 1 below.
Table 1. The effect of differing phosphate levels provided over a 6 or 12-month period, on the reproductive performance of beef cows on the Armoedsvlakte. (Adapted from de Waal et al., 1996).
| Treatment | Months of Supplementation | Level of P supplementation (g/h/d) | Calf %
(1985-1989) |
Weaning % (1985-1989) | |
| LP 6 | 6 months (Sep-Feb) | 5 | 73.3 | 71.1 | |
| MP 6 | 10 | 84.1 | 77.3 | ||
| HP 6 | 16 | 85.2 | 74.1 | ||
| LP 12 | 12 months
|
Mar- Aug
3 |
Sept-Feb
5 |
77.8 |
70.4 |
| MP 12 | 6 | 10 | 83.0 | 77.4 | |
| HP 12 | 9 | 16 | 86.0 | 86.0 | |
The Benefit of Different Phosphate Sources
When buying any phosphate product, producers must differentiate between the different sources available. Traditionally, bone meal was considered an organic source of phosphorus for grazing cattle to abate phosphorus deficiencies. However, several diseases caused by bacteria, namely Salmonella and Bacillus anthracis (which causes anthrax) reared their heads, causing great financial losses. Due to these diseases, regulations were placed that bone meal intended for use in animals must be sterilised through a steaming process. Should bone meal be considered as a source of phosphorus, producers should keep in mind that variation exists between various bone meal sources, and the bioavailability of the phosphorus within the product can range from 50-80%.
Dicalcium phosphate/Monocalcium phosphate
In the animal nutrition industry, inorganic sources of phosphorus are used when producing phosphate products, namely monocalcium phosphate (MCP) and dicalcium phosphate (DCP). Monocalcium phosphate is a rich source of phosphate with the highest bioavailability (80%), which promotes animal performance when used in rations or supplements. The differences between various phosphorus sources are indicated in Table 2 below:
| Phosphate source | Calcium (Ca) (%) | Ca-bioavailability (%) | Phosphate (P) (%) | P-bioavailability (%) |
| Sterilised bone meal | 30 | 95 | 12 | 65% |
| Dicalcium phosphate (DCP) | 21 | 94 | 19 | 75% |
| Monocalcium phosphate (MCP – P21) | 16 | 95 | 21 | 80% |
Table 2.
Voermol Superfos is the optimally balanced
Voermol uses the highly bioavailable source of phosphate, Monocalcium phosphate, in the production of Voermol Superfos (V17422). In addition to the phosphate source, organic trace minerals, which support enhanced reproductive performance, health, and fertility, are included in Voermol Superfos. Organic trace minerals are more biologically available to the ruminant, as they utilize an alternative absorption route than inorganic minerals.
