Phosphorus is an expensive nutrient in feed formulation, and because it can cause eutrophication, the better knowledge on the utilisation of P will lead to reduced feed costs and reduced pollution potential. Numerous studies have looked at the evaluation of P nutritional value from raw materials and feeds beyond the total P content following different concepts and different systems of evaluation.
EMEA Sales &Technical
Services Manager AB Vista
EMEA Technical Manager
AB Vista
Global Support Manager
AB Vista
Phosphorus* (P) is the second most abundant mineral in the body following calcium (Ca) and is an essential element in poultry diets. It plays key metabolic roles such as development and maintenance of skeletal tissue, maintenance of osmotic pressure and acid base balance, energy utilisation and transfer, protein synthesis, transport of fatty acids, and cell differentiation (DNA). Phosphorus in animal feeds comes from plant-based, inorganic mineral sources, fish and meat and bone meal. An important part of plant P is in the form of phytates, which are ionic forms of phytic acid. Phosphorus in phytate form is mostly un-available for monogastric animals under commercial conditions because they lack an adequate capacity to hydrolyse phytate and its lower esters to release phosphates that are then available. Phosphorus from mineral origin comes from phosphate rock which is treated in different ways to yield the various products available on the market. Inorganic phosphates are the most important source of P in animal feed, although their levels of incorporation in diets have been reduced drastically over time with the supplementation of phytase in feed, especially since the last phosphate crisis in 2007/2008. Knowledge of the phytate content of ingredients and feeds became an essential part of understanding how much phytase needed to be used to replace a given amount of P from the mineral sources, while maintaining growth performance and good quality of bone mineralisation.
Because phosphorus is an expensive nutrient in feed formulation, and because it can cause eutrophication, the better knowledge on the utilisation of P will lead to reduced feed costs and reduced pollution potential. Numerous studies have looked at the evaluation of P nutritional value from raw materials and feeds beyond the total P content following different concepts and different systems of evaluation.
Currently, P evaluation in poultry is based on three different principles:
1. NRC (1994) refers to non-phytate P as the difference between total P and phytate P assuming inorganic P completely available whereas organic P is not,
2. INRA (2004) approach based on a bio-assay adding graded level of dietary P of a test and a reference phosphate to a P deficient basal diet to calculate from the slopes the relative biological value (RBV) or available P,
3. CVB (1997) approach is based on the determination of P retention using P deficient diets (on a 3 days balance study following 10 days adaptation period).
More recently some trials were conducted to give digestible phosphorus (ileal digestibility) values representing the part of P that may be absorbed in the digestive tract of the animals. But digestibility trials depend on a lot of factors from the diet but also on the animal physiology and gave so far non consistent results (Rodehutscord et al.,2016).
When considering dietary P level, independently of the methodology chosen, it is impossible to ignore the dietary Ca as this has such a large effect on P absorption and utilization. The body maintains the serum levels of these minerals within narrow and stable limits. Absorption of Ca and P from the diet occurs mainly in the duodenum. An imbalance between Ca and P supply can interfere with their digestibility and their metabolic use. Excess Ca will impair P absorption, increase gastrointestinal pH and could have implications in gut health such as necrotic enteritis, affecting the performance of the animal and bone mineralisation. It is therefore crucial to analyse P and Ca in feed.
NIR AS A TOOL TO CHARACTERIZE PHYTATE
NIR technology uses near infra-red light to quickly and easily analyse ingredients and feeds to predict their nutritional value. Traditionally NIR technology has been used for routine proximate analysis such as moisture, protein and crude fibre for different applications including positive acceptance/release of ingredients and feeds and identifying trends in raw material quality to update the formulation in order to ensure consistent feed quality.
Recent advances in NIR calibration technology now enable us to predict additional parameters such as reactive and total lysine for soybean meal, protein solubility index for corn and sorghum, and phytate-P. The phytate-P content varies between ingredients and also within ingredients. Figure 1 demonstrates the variation of phytate-P in and between some of the key ingredients that are used in Europe, Middle East and Africa (EMEA).
The variation in phytate-P content of the raw materials inevitably causes variation in the phytate-P content of the feed. Figure 2 shows typical variation of phytate-P content for one feed compounder in EMEA.
If not accounted for, in the feed formulation, variations in dietary phytate can result in an underestimation of phosphorus release by phytase that will result in non-optimal animal performance and diet cost.
PHYTASE AS PART OF THE MAXIMUM MATRIX NUTRITION (MMN) STRATEGY
Maximum Matrix Nutrition is a concept developed by AB Vista whereby a better understanding of enzyme matrices, and the characteristics of the ingredients employed allow the customer to better utilise additives such as enzymes and stimbiotics in least cost feed formulation. This approach doesn’t only consider the release of minerals by the phytase but also the release of other nutrients (amino acids, metabolizable energy etc.) which arise due to the combination of phytate destruction, inositol production, fibre hydrolysis and the stimulation of lower gut fermentation, all interacting between each other.
There are 2 main key points before considering this nutritional strategy:
1. A detailed understanding of the substrate (phytate-P and total dietary fibre) is essential and is achieved by implementing regular quality control checks to avoid under but especially overestimating the use of phytase.
2. Enzyme product reliability to ensure confidence in the matrix values.
This strategy means the inclusion of an inorganic source of phosphate will be reduced and even removed from the formulation completely, especially in the grower and finisher phases in poultry. This is only feasible if you have a detailed understanding of the substrate and in using the latest generation phytase like Quantum Blue.
Recent research (Poernama et al., 2020, in press) has shown that using 1500 FTU/kg of Quantum blue allowed all MCP to be removed from 10 to 42 days with no loss in performance or bone ash compared with broilers fed a diet with MCP throughout. Phosphorus savings for this study were 0.23% available P for a diet containing 0.25% PP. For the overall period this means a reduction of 31.7 kg MCP/ton of feed which represents a saving of 15€-/ton of feed when the price for phosphate is 480€/ton but can be 31.7€/ton of feed when MCP price reaches 1000€/ton like in 2008.
Apart from the savings related to phosphorus release from phytate bound P, the savings due to application of MMN in amino acids and energy also has a significant influence in the final production cost. AB Vista has conducted extensive research to further understand the quantity of amino acids, minerals and energy that can be spared using higher doses of Quantum Blue phytase in combination with Signis or Econase XT. For a standard feed containing an average of 0.25% PP, the use of 1500 FTU/kg compared with 500 FTU/kg can increase the feed cost savings by 6€/ton when considering the full nutrient savings of the enzyme. This concept will also contribute to a reduction in the environmental impact caused as a result of optimising the use of P from dietary PP and reducing the inclusion of inorganic phosphate, which is a non-renewable resource, while giving the producer a tool to fit with its objectives of balancing production cost and maintaining growth performance.
*Phosphorus: an essential component and different systems of evaluation
