Evaluation of organic and inorganic phosphates bioavailability through in vitro solubility and in vivo utilization

Abstract

To determine the quality of phosphorous sources, we have studied the in vitro solubility and the in vivo
bioavailability of animal and mineral sources and the effect of a particle reduction (only for organic sources) and phosphorus level was evaluate in laying hens as model. Trial 1: The P sources, meat and bone meal (MBM,6.0 % of total P), bone ash (BA, 15.5 % of total P), diammoniun phosphate pure (ADP, 27.8 % of total P) and the dicalcium Phosphate (DP, 18.3 % of total P) were incubated in vitro by both a chemical and enzymatic methods and the soluble phosphorus was measured. Trial 2. Birds (eight/treatment) received a low-P diet (0.329 % total
P) or a low-P diet with a load of 0.075; 0.15 or 0.25 g of P coming from ADP to determine the minimun P stirequeriment .Trial 3: Eight birds/treatment received a low-P diet or a low-P diet supplemented with an amount of 0.075 g of P coming from ADP or DP or MBM or BA. The MBM and BA were ground to a coarse or a thin particle . Trial 4. As the trial 3 but with a load of 0.25 g of P coming from the same sources. We have measured P intaked and excreted in a 48 hours trial balance. The bioavailability was determined using ADP as a reference. When the level of P was 0.25 g/day the bioavailability of P from DP was inferior to ADP and the animals sources. The grounding affected the digestive utilization of P from MBM at low dosis of P. The in vitro solubility has well relationed with the in vivo P availability in inorganic sources but not in organic sources of P. The implementation of grounding seems not to be clearly justifified.