IN 2003, Danisco Animal Nutrition launched Phyzyme XP, the first new generation Escherichia coli phytase produced in yeast Schizosaccharomyces pombe.
This new generation E. coli phytase has been proven to be at least 20% more effective than fungal phytases at releasing phosphorus and has shown further improvements in calcium, energy and amino acid release. The benefits to the poultry producer are even greater feed cost savings and reduced costs associated with environmental management.
Efficacy
Compared to fungal phytases, this new generation E. coli phytase is more resistant to breakdown by the animal's own proteases as well as having a higher relative activity over a wider pH range. This means the new generation phytase is more effective throughout the digestive tract compared to other leading phytase products (Tables 1 and 2).
Phytase
Phytate is not only a potential phosphorus source but also an anti-nutrient that can bind other costly nutrients, reducing the supply of energy and amino acids to the animal. The diet digestibility is reduced because these bound nutrients are less available.
As the level of dietary phytate increases, the digestibility of the diet is reduced (Figure 1).
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Phytases release phytate-bound nutrients. This new generation E. coli phytase releases more energy and amino acids as dietary phytate levels increase (Figure 2).
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Traditional use of 'fixed' nutrient matrix values for phytase in the feed formulation fails to consider that the response to phytase will vary with factors such as dietary phytate level, bird age and phytase dose rate.
Feed cost savings
Traditionally, phytases tend to be included in the feed at fixed inclusion rates. With increasingly competitive phytase prices, there will be cases where higher inclusion of phytase can release more phytate-bound nutrients, offering a higher return on investment to the feed producer (Figure 3).
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To help nutritionists establish the most economic use of phytase in their feeds, Danisco has developed the Phycheck service. This service includes a unique software program initially focused on broiler feeds that calculates specific matrix values for phosphorus, calcium, amino acids and energy according to phytase dose rate, dietary phytate level and bird age.
By using these scientifically proven matrix values, nutritionists can op timize phytase in their diet formulations to maximize feed cost savings.
Scientific results
The software program is derived from extensive digestibility and bird performance trials conducted in the U.S., Canada, Brazil, U.K. and Australia/New Zealand that cumulatively contributed more than 100 individual data points.
The diets used in the trials were corn/soy based and varied in phytate level by using higher phytate raw materials such as rice bran and canola meal. The new generation E. coli phytase was added to the diets at 250, 500, 750 or 1,000 phytate units (FTU) per kilogram of feed. Daily gain, feed intake and feed conversion were measured, together with energy (AME), ileal amino acid digestibility and phosphorus and calcium retention at 21 and 42 days of age.
The digestibility and performance results were compared to birds fed diets reduced in phosphorus and calcium with no phytase supplemented.
A 'multi-factorial model' was then developed to describe the bird responses--like improvements in AME and amino acid digestibility--according to phytase dose rate (250-1,000 FTU/kg feed), dietary phytate phosphorus level (0.23-0.33%) and bird age (0-21 or 22-42 days).
Phytase improved dietary AME, ileal protein and amino acid digestibility at all concentrations. There were also significant interactions between phytate level and phytase dose rate and other complex interrelationships. The software accounts for these interrelationships when calculating specific matrix values for phosphorus, calcium, amino acids and energy.
The digestibility data supported Danisco's bird performance trials, indicating that this new generation E. coli phytase liberates at least 20% more digestible phosphorus than fungal phytases at a dose of 500 FTU/kg feed. Calcium release was around 10% higher for the same phytase addition rate. Amino acid and energy release was also higher and was influenced by the complex interaction of phytase dose rate, dietary phytate phosphorus level and bird age.
Efficacy
Matrix values derived from the new software were validated in broiler performance trials in the U.S. (Auburn University) and the U.K. (ADAS) using corn/soybean meal based-diets.
These trials demonstrated that adding the new generation E. coli phytase at varying levels to diets reduced in phosphorus, calcium, energy and amino acids (according to Phycheck) maintained performance, offering considerable feed cost savings.
Feed cost savings
In today's challenging and increasingly competitive market, broiler producers can benefit from this new advancement in phytase optimization. Producers aiming to maximize feed cost savings can now apply phosphorus, calcium, energy and amino acid matrix values to phytase to fully exploit its potential, without risk to bird performance.
What could this mean for broiler producers in the U.S.? According to recent feed ingredient prices, and assuming 'simple' corn/soybean meal-based diets, feed costs could be reduced by $6 per ton--$1.50-2.00 more than using fungal phytases with fixed matrix values for calcium, phosphorus, energy and amino acids.
As phytase use continues to grow throughout the world and product choice for poultry producers and feed manufacturers becomes more diverse, so does the need for reliable tools to compare and optimize phytase use for maximum economic benefit.
JANET REMUS *
* Dr. Janet Remus is technical services manager for Danisco Animal Nutrition.
1. New generation E. coli phytase is most resistant to breakdown Remaining in vitro phytase activity after treatment, % Treatment E. coli Fungal Fungal phytase phytase 1 phytase 2 Pepsin 76.7 (a) 31.4 (b) 5.42 (c) Trypsin 23.0 (a) 0.45 (b) 1.25 (b) Chymotrypsin 65.8 (a) 2-95 (b) 5.77 (b) (a,b,c) p < 0.05. 2. New generation E. coli phytase has the highest relative activity in the digestive tract of pigs and poultry (from Kumar et al., 2003) Average relative phytase activity *, % E. coli Fungal Fungal phytase phytase-N phytase-R Crop (pH 4-5) 97 84 91 Proventriculus (pH 4-5) 97 84 91 Duodenum (pH 3.5-5.5) 90 77 86 Stomach (pH 2-5) 78 65 65 Gizzard (pH 2-3) 60 54 35 * Phytase activity expressed as relative to maximum (100%) activity.
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