Evaluation of the real phosphorus digestibility in feeds phosphates

Phosphorus is an essential mineral in animal nutrition. It is involved in many biological processes such as bone formation, energy metabolism, cell structure and egg formation.A diet low in phosphorus has serious consequences on zoo technical performance. While a phosphorus intake greater than nutritional needs leads to excess phosphorus emissions in animal waste, contributing to environmental pollution. Hence the importance of assessing the biodigestibility of mineral and organic sources of phosphorus. The use of a highly digestible feed phosphate such as Phosfeed 21 optimises the costs and the quality of the formula while meeting the nutritional needs of the animal. It also leads to better growth performance levels thanks to a better feed conversion rate (FCR)*.

Hence the importance of evaluating the bio-digestibility of the different mineral and organic sources of phosphorus (see figure), in order to estimate the fraction of phosphorus actually absorbed at the intestinal level. This will better cover the nutritional needs of the animal while reducing phosphorus excretion in its faeces, and consequently contributing to environmentally friendly breeding.

The digestibility of the feed phosphate was measured through in vivo tests, which require advanced technical expertise and considerable human and financial resources, by relying on the WPSA protocol considered by research centres and universities to be the most appropriate approach for this type of study.

This method measures the real phosphorus digestibility by combining radioactive markers to measure the endogenous phosphorus mobilised in the animal body, allowing the determination of real phosphorus digestibility values.

This approach involves comparing the phosphorus biodigestibility of several mineral and organic sources in a group of animals that are homogeneous in terms of species, strain, sex, and age. This is done under normal technical conditions (feeding, prophylaxis, etc.), according to a reliable and appropriate statistical protocol (ANOVA).

An in vivo study in line with WPSA protocol

The study protocol was largely in line with the World Poultry Science Association (WPSA) protocol for the determination of P availability in poultry, based on pre-caecal absorbability. The experiment conducted at the research facility of Wageningen Bioveterinary Research evaluated the precalculus absorbability of phosphorus (P) and calcium (Ca) in broilers from 9 mineral sources of phosphorus and one organic source (pork meal).

In this study, 5 monocalcium phosphates (Ca (H₂PO₄) 2-H₂O), 3 mono dicalcium phosphates (CaHPO₄.Ca (H₂PO₄) 2-H₂O) and a meat bone meal of porcine origin, were evaluated. All phosphate sources tested are commercially available products.

The study revealed a record digestibility rate of 90.3% for the Moroccan mono-dicalcium phosphate Phosfeed 21. This rate is higher than for the other sources of mono dicalcium phosphates MDCP/Europe (79.2%) and MDCP/America (80.2%) with a statistically significant difference. It is also the highest rate ever measured for a mono-dicalcium phosphate and ­comparable to that of the monocalcium phosphates MCP 22.7.