- the P present in the feed materials which is not bound as phytate-P
- the inorganic P added to the feed (e.g., monocalcium phosphate (MCP), dicalcium phosphate (DCP))
- the P released from phytate by phytase
Phytases are used to liberate P bound to phytate present in feedstuffs. Consequently, less P from inorganic sources needs to be added to the diet to fulfill animal requirements, thus lowering the cost of the feed.
Economic savings on the feed formulation cost using a phytase
The economic saving of a phytase is determined mainly by the cost of the inorganic P (MCP, DCP) added to the feed, and the capacity of the phytase to liberate P from phytate present in the feed (the P matrix values).
The higher the P matrix value for a certain dose of phytase, the more inorganic P can be replaced, and the cheaper the feed becomes. Similarly, increasing the dose of a phytase will allow more inorganic P to be removed, reducing the feed cost even further.
Nowadays, a single dose of phytase (500 FTU/kg) is common practice. However, the question remains if double dosing a phytase makes the feed formula even more economical (cheaper), considering that a double dose of phytase means double the phytase cost.
An example of the economic savings using OptiPhos® Plus at a single and double dose on a feed formulation containing MCP (21% P) at a price of €400 or €500/T is shown in Table 1.
Based on the matrix values of OptiPhos® Plus, increasing the dosage from 500 to 1,000 FTU/kg reduces the feed cost by €0.40 to €0.50/kg, while for pigs it ranges from €0.68 to €0.86/T of feed. This means that if the inclusion cost of 500 FTU OptiPhos® Plus per ton of feed is below that cost, it makes economic sense to include OptiPhos® Plus at a double dose.
Recommendations on inclusion level of OptiPhos® Plus
However, the calculations in Table 1 only make sense when there is enough available P (aP) from MCP or DCP in the feed formula to be replaced by aP liberated by OptiPhos® Plus. This is largely determined by the aP values at which the nutritionist formulates, and the aP which is present already in the feed coming from the different feedstuffs.
As can be seen in Table 2 for broilers and turkeys, the amount of aP from inorganic sources is higher than the aP matrix values of OptiPhos® Plus at 500 and 1,000 FTU/kg (1.55 and 1.76 g/kg, respectively). Therefore, it should be the recommendation in broilers and turkeys to go for at least double dosing to reduce feed costs.
A similar calculation can be made for pigs, knowing the digestible P (dig. P) values of OptiPhos® Plus is 1.12 g dig. P (1.40 g aP) and 1.40 g dig. P (1.75 g aP) for 500 and 1,000 FTU/kg dosing in the feed, respectively (Table 3). It can be calculated that for pig(let)s up to 40-50 kg and for sows in lactation, a minimum double dose of OptiPhos® Plus is advised to optimize feed cost formulation.
Superdosing
Note that these calculations do not take into account the superdosing effect obtained by phytase. The faster degradation of phytate will lead to a quicker release of the nutrients captured in the phytate, improving their digestibility and so improving animal performance. This also contributes to an even better financial return on investment.
Conclusion
Based on the economic calculations and knowing the cost of the inorganic P sources and their inclusion levels in the feed, using a double dose of OptiPhos® Plus in broilers, turkeys, pigs up to 40 kg body weight and sows in lactation should be the standard. The superdosing effect of OptiPhos® Plus will further contribute to better technical performance, improving profitability.
