Although cereals make up the largest part of any feed formulation, most of the phosphorus (P) contribution comes from the protein sources. This is true for both free P, but also for P in the form of phytate (phytate-P) which represents 64 - 91 % of total P. In feed formulations, approximately 60 - 75 % of phytate-P comes from the protein sources while the remainder comes from the cereal source (Table 1).
Table 1. Total P and phytate-P levels in feed materials
Total P (g/kg) | Phytate-P (g/kg) | Phytate-P/total P ratio (%) | |
Protein sources | |||
Soybean meal | 6.6 | 4.6 | 70 % |
Rapeseed meal | 10.5 | 7.9 | 75 % |
Sunflower seed meal | 10.3 | 8.2 | 80 % |
Rice feed meal | 16.5 | 14.9 | 90 % |
Full fat soybeans | 5.0 | 3.5 | 70 % |
Cereals | |||
Corn | 2.4 | 2.1 | 88 % |
Wheat | 2.8 | 1.8 | 64 % |
Barley | 3.1 | 2.3 | 74 % |
Sorghum | 2.7 | 1.9 | 70 % |
Triticale | 3.4 | 2.2 | 65 % |
Rice | 0.9 | 0.8 | 89 % |
Cereal by products | |||
Corn bran | 4.0 | 3.0 | 75 % |
Wheat bran | 8.2 | 7.0 | 85 % |
Rice bran | 14.2 | 12.7 | 89 % |
Source: CVB, 22016
The determination of P matrix values for phytase enzymes are usually estimated using corn/soy diets. Therefore, if soybean meal is replaced with an alternative protein source like sunflower seed or rapeseed meal, and corn is replaced by wheat and barley, does this have an impact on the P matrix values of OptiPhos®?
A recent research trial carried out at Wageningen University investigated the effect of OptiPhos® at single, double or triple dose on the degradation of phytate-P from different protein sources and cereals using an in vitro digestibility model, mimicking the function of the stomach/gizzard and the small intestine. The results are shown in Table 2. The full Technical Bulletin can be downloaded here.
Table 2. Improvement in P release (mg/g feedstuff) and phytate-P degradation by OptiPhos® at different levels
Feed material | Phytate-P (mg/g) | Improvement in P release (mg P/g feed material) vs control * | Phytate-P degradation (%) ** | ||||
250 OTU | 500 OTU | 750 OTU | 250 OTU | 500 OTU | 750 OTU | ||
Soybean meal | 3.3 | 1.80 | 1.83 | 1.94 | 54 | 56 | 59 |
Sunflower seed meal | 5.9 | 4.64 | 4.80 | 5.05 | 79 | 81 | 86 |
Rapeseed meal | 8.0 | 5.57 | 5.49 |
5.56 |
70 | 69 | 70 |
Barley | 1.6 | 0.62 | 0.73 | 0.79 | 39 | 46 | 49 |
Corn | 1.5 | 1.04 | 1.08 | 1.14 | 70 | 72 | 76 |
Wheat | 1.5 | 0.75 | 0.78 | 0.82 | 50 | 52 | 55 |
* Total P release by phytase at a certain FTU minus total P release in control diet
** Improvement in P release / total phytate-P in feed material
All doses were significantly different compared to the control (p < 0.05)
The trial concluded that:
Based on this data, OptiPhos® will release:
Conclusion