Phytases beyond phosphate, how inositol improves feed conversion ratio in poultry

We feed large amounts of cereal grains and beans to animals. The efficiency with which animals convert feed to body weight is the most important measure of the productivity of intensive animal agriculture. Feed conversion ratio (FCR) is the amount of feed (kg) required to increase body mass by 1kg. Of the animals, fish, poultry, pigs and cattle that are farmed intensively in the UK, fish are the most efficient converters of feed into body mass, with a FCR of 1. Poultry, depending on the species and feeding period, have a FCR of < 2, while pigs and cattle are much less efficient.

One way in which farmers can improve FCR is by the addition of enzymes to animal feed. Our partner in this project, AB Vista Feed Ingredients, a division of AB Agri, a part of Associated British Foods, ABF, is involved in the development and distribution of feed enzymes including phytases. Phytases are essential for efficient use by the animal of a phosphate-rich molecule that is the major storage form of phosphorus in feed components of plant origin like grains and soy beans. The phosphate rich molecule, phytate, or inositol hexakisphosphate, contains six phosphates for every inositol. Inositol has some similarity to sugars, but, unlike sugars, we know little of its digestive use to the animal. In contrast, phosphate is known to be hugely important to mineral nutrition, bone development and growth of animals.

Companies in ABF including AB Vista Feed Ingredients have substantial programs of research for improvement of phytases in respect of their application and their intrinsic properties. There are several drivers of this research: improvements in animal growth afforded by access to phytate-bound phosphate in the dietary feedstuff and avoidance of anti-nutrient effects of dietary phytate. The use of enzymes to access phosphate in feeds means that less of this essential nutrient needs to be added as rock phosphate (commonly dicalcium phosphate). It has been estimated that the addition of less than $1 worth of enzyme spares rock phosphate costs of $4-6/tonne of feed.

Many companies undertake poultry feeding trials to show that their enzymes work. A common approach is to feed animals with different amounts of phytase in a randomized trial design and to measure animal performance. While many trials highlight the value of phytase addition to animal feed, few companies measure phytate degradation by analysing gut contents (digesta) for phytate and its inositol phosphate degradation products. AB Vista Feed Ingredients does because the approach explains how their products work, enabling development of better products.

New research suggests that inositol released from feed during digestion is beneficial to animal growth. The mechanisms by which inositol improves animal growth is unclear. While we may reasonably assume that inositol generated during digestion enters the blood and is transported to tissues very few scientific studies have been made of the subject.

The applicants, Charles Brearley, Gabriel Mutungi and AB Vista Feed Ingredients have over 20y experience, respectively, of inositol phosphate and inositol analysis, of muscle physiology including of farmed poultry, and of the use of feed enzymes in animal nutrition. Our programme of research is designed to reveal how inositol, released by phytases, improves nutrition in poultry. We will exploit newly developed methods that allow measurement of inositol in feed, digesta and plasma and adapt these methods to analyse inositol in muscle tissue. Additionally by analysis of the physiology of muscle, we expect to explain how inositol improves muscle growth, identify the key benefits of phytases and so improve the phytase dosing regimens of farmed poultry with consequence for the environment and the consumer.

Our published work shows correlation between exogenous enzyme- (phytase) mediated release of inositol from feed, measured in gizzard contents, and body weight gain in poultry. To provide a deeper understanding of the effects of inositol and its practical benefits to animal nutrition, we will:
1) Measure inositol content across the GI tract, in gizzard and ileum contents as a function of phytase dose. Samples taken from the gizzard and ileum, provided by the industrial partner from feeding trials designed for this project, will be analysed by 2d-HPLC with pulsed amperometric (PAD) detection; 2) Measure inositol content of plasma as a function of phytase dose. Plasma provided from the above feed trials will be analysed by 2d-HPLC-PAD; 3) Measure inositol content of muscle tissue as a function of phytase dose. Muscle tissue provided by our industrial partner from feed trials will analysed by 2d-HPLC-PAD; 4) Measure inositol phosphates across the GI tract, gizzard and ileum, in plasma and in muscle tissue. We will apply a range of HPLC separation techniques either with suppressed ion conductivity detection or with post-column complexation of inositol phosphates to the feed and digesta samples provided by our industrial partner; 5) Correlate measurements 1, 2, 3, and 4 with indices of animal performance. The parameters of animal performance that we will measure include, feed conversion ratio, body weight gain, tibia strength and/or mineralisation; 6) Undertake assessment of muscle physiology as a function of phytase dose, correlating it with circulating (plasma) and tissue inositol content. We will measure: slow vs fast twitch bundle composition; fat, carbohydrate and protein levels; inositol content; inositol phosphate content and Akt/mTOR pathway activation.

Supplementation of animal feed with enzymes improves animal nutrition and this explains why approximately 90% of the pig and poultry feeds manufactured worldwide include exogenous enzymes. The feed enzyme market was worth $650m in 2010 with annual growth in the past of 13% (2010, Barletta in Bedford and Partridge: Enzymes in farm Animal nutrition). The internal estimates of our industry partner suggest that growth might even have increased. Of the principal enzyme groups in the feed enzyme market, non-starch polysaccharases and phytases, the latter account for approximately 50% of the sales volume.

Our proposal is a collaborative program of research between UK industry, AB Vista Feed ingredients, a division of the AB Agri group of Associated British Foods, and academia. It involves fundamental and applied research in the area of sustainable agriculture.

The research described in this proposal affords opportunity for a radical reappraisal of the physiological explanation of the efficacy of phytase adjuncts to animal feed. Our proposal addresses a research problem that the feed industry and the academic partners have identified and our proposal offers solution to that problem. Put simply, with ever increasing pressure on food and animal feedstuffs, feed conversion ratio and/or body weight gain is/are the most critical index of the efficiency of intensive animal agriculture. This proposal goes to the heart of feed conversion ratio and the contribution that enzyme adjuncts make to that. BBSRC has identified sustainable agriculture as a high-level priority area in its Strategic Plan 2010-2015.

The potential impacts of this work are multifaceted. Because we will publish our research in poultry nutrition journals, read by the whole industry, from farmer to feed mill to integrated poultry producers to animal nutrition scientists in academia and the regulatory bodies, our work will inform all companies who undertake their own feed trials in poultry and will enhance the research capacity, knowledge and skills of businesses developing products in this field.

Our industrial partners attend several applied animal nutrition conferences worldwide each year and regularly chair sessions or give plenary talks thereat. Consequently, our research will be prominently reported to experts in the field.

AB Vista has sophisticated marketing strategies, dedicated marketing specialists and a global reach and reputation that ensures the outputs of its research are disseminated widely to, and by, feed industry analysts whose own outputs are keenly followed by the industry and also by commodity traders.

Advertisement of the outputs of our research will also include direct press releases by AB Vista Feed Ingredients.

The impacts to be expected extend to improvements in animal nutrition and reductions in cost in the food supply chain, amelioration of phosphate outputs to the environment and reductions in mined mineral inputs to agriculture. The impacts are acute in the context of intensive poultry production. Because phytases are employed world-wide, this work has global relevance.

This project will provide excellent training opportunities for the PDRA in analytical biochemistry and animal nutrition and will give the scientist unrivalled access to expertise in the commercial arena of a biotechnology industry with agricultural focus. The Norwich Research Park (NRP) is an exemplar of excellent plant research and the postdoctoral scientist will have ample opportunity to extend his/her presentational skills and network within the local scientific community. The collaboration between the UEA groups and the industrial partners will extend these opportunities by contributing towards the pool of highly skilled researchers who can contribute with a skill set demanded by the animal feed industry to the UK economy. This project enhances the reputation of the NRP as an industry-aware research environment.