A New Phytase with Reliable Matrix Values
The phosphorus (P) matrix values of a phytase provide the nutritionist with information about how much inorganic P can be replaced by a phytase in the feed. To provide reliable matrix values, multiple trials need to be conducted. This can be assessed either by regular digestibility trials or by bone ash trials. In such trials, the amount of P released from the substrate phytate is determined as a result of adding phytase to the diet at different doses.
Reliable matrix values based on all trial data
In poultry, 12 trials have already been carried out to determine the average available P (aP) improvement for different inclusion levels of OptiPhos® Plus (Figure 1). In pigs, 11 trials have been conducted from which the average improvement of digestible P (dig.P) was estimated (Figure 2). In both graphs, the average response from all the conducted trials is shown, in addition to the average response taken from only the best trials from each species (i.e., the best six poultry trials and the best three pig trials).
Figure 1. Response in aP at different inclusion levels of OptiPhos® Plus in broilers (average of all 12 trials), or only considering the six trials showing the highest P response
Figure 2. Response in dig. P at different inclusion levels of OptiPhos® Plus in pigs (average of all 11 trials), or only considering the three trials showing the highest P response
The response at 500 FTU/kg in poultry, for example, provides an aP matrix value of 1.55 g aP/kg of feed when considering all trials, but 1.65 g aP/kg of feed when considering the six trials that gave the highest aP response.
For pigs, it can be deduced that an OptiPhos® Plus dose of 500 FTU/kg provides a dig. P matrix value of 1.12 g per kg of feed when considering all trials, and a value of 1.25 g/kg when only the best three trials are considered.
An additional feed cost saving of €0.22 per tonne of feed for broilers, and €0.35 per tonne of feed for pigs can be calculated when the P matrix values originating from only the best trials are considered versus when the P matrix values derived from all trial data are used for the feed formulation (Table 1).
Table 1. Impact on feed cost saving when using the matrix values derived from all trials or only from the selected best trials.
This difference might be a trigger to only use the best trials for establishing the P matrix values in order to be the best buy for a nutritionist. However, using only the best trial results increases the risk for the nutritionist that P deficiency issues might occur, leading to lower animal performance. Therefore, it is better to rely on the average P matrix values of all conducted trials, and not only those from the best trials.
Conclusion
Reliable and safe P matrix values originating from multiple trials are required to avoid any risk of P deficiency, and by consequence, financial losses, at farm level. The P matrix values of the new phytase OptiPhos® Plus are based on multiple trials, taking the average from all trials, making them very reliable.