Abstract:
1. For the determination of phosphorus it is recommended to use a calcium to phosphorus ratio of 2:1. If phosphorus levels below the recommended levels are used, other nutrients must be adjusted in ratio to prevent an influence on phosphorus availability. 2. The availability of phosphorus is not influenced if the manganese level is 80 mg.kg<sup>-1</sup> feed and if the calcium to phosphorus ratio is increased from 2:1 to 3:1. An excess of both the manganese and calcium have a negative influence on phosphorus availability. 3. Vitamin D has no negative influence on the availability of phosphorus as long as the calcium to phosphorus ratio is 2:1. An excess of both Vitamin D and calcium have a negative influence on phosphorus availability. 4. The levels of feed ingredients as well as the combinations in which feed ingredients are used to each other have an influence on the availability of phosphorus. The influence of inorganic phosphorus on the total phosphorus in the diet is also caused by the combination of feed ingredients. 5. The sex of the broiler has an influence on the availability of phosphorus because there is difference in phosphorus utilization between different sexes. When comparing phosphorus availability of phosphorus sources, only one sex can be used. Both sexes must be used to prevent over or under estimation of phosphorus availability.
