|Use of Phytase in Pig and Poultry Feed to Reduce Phosphorus Excretion||Netherlands||1986-1991||Full Scale|
MANUFACTURE OF FOOD PRODUCTS AND BEVERAGES # 23
Phosphorus (P) is an important element in the feeding of pigs and poultry. One third of the P is present in the forage as inorganic P which is easily digestible. The other two thirds is present as organic P especially in the form of phytic acid and phytate. The phosphate stored in this way is not available for poultry and pigs but has to be hydrolyzed first.
The organically bound P can be excreted almost totally. The enzyme phytase is necessary to hydrolyze the organic bound phosphor. This enzyme is not or practically not produced in the alimentary digestive tract of pigs and poultry but does occur in some grains like wheat and barley. Wheat middlings also contain a lot of phytase. However, it was proved that this vegetable-phytase is mainly inactivated during the production stages where with steam addition a temperature of 80 degrees or higher is reached.
In the original process the feed is composed of different components. In Netherlands the most important ones are: barley, wheat, peas, wheat middlings, sunflower meal, tapioca, maize, maize gluten feed, hominy feed, premix (vitamins and minerals).
The most P rich components are mono-calciumphosphate, dicalciumphosphate and monosodiumphosphate [10,11]. To produce these components out of the ore a lot of heavy metals are liberated, giving pollution. For each species or category a minimum amount of a nutrient (e.g. digestible P) is required to enable a high production level. The computer calculates how much of each component is necessary in the food so that it is less expensive and most cost effective . The remaining P which is not easy digestible will be excreted in the manure. In some regions intensive livestock farming results in a surplus of manure; more than can be used as fertilizer. Some elements (phosphorus and nitrogen in particular) find their way into surface water and cause environmental problems when added in excess.
Cleaner Production Principle:
Process modification; Material substitution
Cleaner Production Application:
Microbial phytase can be used as an addition to pig and poultry feed. The enzyme phytase is produced by a special selected and genetic modified fungi, Aspergillus Niger [1,7,8,9]. Fermentation takes place on a large scale, at Gistbrocades in Belgium.
The final enzyme is available in two forms, as a powder or as a liquid. The powdered phytase is placed on the carrier wheat middlings. The phytase hydrolyzes the phytic acid molecule in the stomach of the pigs. With poultry this process already starts in the crop .
Phytase has to come up to the following requirements :
|It is active in the stomach.|
|It is stable, during the working, the storage of the feed and in the gastro-intestinal tract.|
|It can be processed by the feed manufacturer.|
Phytase can not be detected at the end of the small intestine. This is positive because in this way no phytase, produced by genetic modified organisms is excreted in the environment .
To quantify the activity of phytase the expression phytase unit (Fytase Eenheid) FTU has been introduced. A FTU is the quantity of phytase needed to make free 1 micro mole inorganic phosphate out of sodiumphytate in 1 minute, under standard conditions, pH 5,5 and temperature 37oC . The product Natuphos (commercial name) has 5000 FTU per gram. When phytase is added to the feed the digestible P is increased with 27 - 30 percents. Using 500 FTU in pigs feed the amount of digestible P is increased with 0,8 g/kg feed. For broilers it is 1,1 g available P per 500 FTU and lay hens 1,1 g available P per 300 FTU [3,10]. Cavo Latuco, a feed manufacturer, uses feed with 0,3% fytase (FTU=100/g) which is the same as 300 FTU/kg . This results in an average decrease of almost 30% of P in the environment.
Scale of operation
Royal Gist-brocades N.V. is an international group of companies whose core business is biotechnology. The group is one of the largest producers in the world of enzymes. The turnover of this group is 1,565 million (DFL). Pre-mervo is a pre-mix company with a turnover of 100 million (DFL) distributed over a laboratory (4 million), protein continually making (36 million), premixes (60 million). They produce 50.000 ton premix in a year. These are mixes of minerals and phytase but also dilutions of only phytase . Cavo Latuco produces 500,000 ton feed per annum. 273,000 ton is cattle feed, 155.000 ton is pigs feed, 62,000 ton poultry feed and 15,000 other feed . Except for cattle feed all the feeds contain phytase diluted by Pre-mervo .
Stage of development
In 1986 a co-operation agreement was signed between the 'Produktschap voor Veevoeder' (Commodity Board for Feeding stuff) and Gist-brocades n.v. A working group was established in which the following organizations participated: COVP (poultry-research), IVVO (pig feed-research), CNO-TNO (analysis), CVB (central feed bureau) and feed companies. One of the tasks of the working party was to study the possibilities of phytase in feed as a way to reduce phosphorus excretion. Gist-brocades took the responsibility for the production process.
In 1991 the enzyme became commercially available for the feed industry in the Netherlands under the brand-name Natuphos. The product Natuphos is fully implemented in the feed industry. Much research is still being done by Gist-Brocades, especially to investigate the biological effectiveness. The pre-mix factory Pre-mervo and the co-operative Cavo Latuco use Natuphos in feed since it became available. This means that automatically a lot of farmers are using feed with phytase. In 1992 in Holland Natuphos is used in more than 35% of all pig and poultry feeds .
In 1992 the product became available in Germany, Belgium, Austria, and in Switzerland . BASF AG holds the marketing and distribution rights outside the Netherlands .
Material/Energy Balances and Substitutions
The data in table 1 is from Pre-mervo. The quantity of phytase is pure phytase and is mixed to a content of 100 FTU/g. Data on energy is not available but is assumed to be slightly more than in the conventional process. The water use and waste generation are the same for the conventional and new process. The changes of the feed company Cavo Latuco were small. They use phytase from Pre-mervo (without minerals), the changes in feed content as seen in table 1 is not comparable with the feed of Cavo Latuco.
Table 1 : Material/Energy Balances and Substitutions of the premixes with minerals 
|Material category||Quantity before||Quantity after|
|phosphate in manure / mean present fattening|
|Pig/year (see below)||7.4 kg||5,2 kg|
|feedstock use||300 g monocalcium phosphate (22,5%)/100 kg||6 g phytase/100 kg|
(Footnote : This quantity is the lump standard in the Netherlands in 1994, the quantity after the use of phytase is equal to the lump standard in 1995, some farmers already meet this standard by phase foddering or other measures.)
Table 2 : Data Cavo Latuco, fattening pig feed .
|Component||Percent (no phytase)||Percent (phytase)|
(The figure for phytase in table 2 refers to the premixed formulation obtained from Pre-Mervo)
The data given in table 3 and 4 are obtained from Pre-mervo, they advise this composition to the feed company. The P content is reduced as well as the nitrogen (in crude protein). In this example only a small amount of phytase is added. This means that the reduction of phosphate in the manure is not optimal and will be below the 30% mentioned later in this case study. The feed from Cavo Latuco gives more reduction of phosphate in the manure.
Table 3 : Example of feeds for fattening pigs .
|Component||No phytase, high crude protein (percent)||Phytase, low crude protein (percent)|
|palm pit flakes||5||3.1|
|rape seed meal||7.5||7.5|
Table 4 : Mineral content of feed for fattening pigs .
|Mineral||no phytase high crude protein (g/kg)||with phytase low crude protein (g/kg)|
|price (DFL) per 100 kg||41.68||41.76|
The data on phytase content in table 2 and 3 do not seem to be comparable (i.e. 0,3% and 0,04%, respectively). Probably the word phytase in these tables refers to different phytase formulations.
The amount of added monocalciumphosphates varies with the feed composition and depends on the amount of digestible phosphorus present in the other constituents of the feed. Therefore no general exact reduction of added monocalciumphosphate can be given.
Environmental and Economic Benefits:
|The excretion of phosphorus can be reduced by 30%, by replacing feed phosphate with phytase and by equally calculated digestible P content. Application of phytase in all the pig and poultry feed in the Netherlands would result in 20 million kg less phosphate in the manure [2,3].|
|Addition of phytase to the feed of piglets gives positive technical results in some experiments; a significant increase of growth rate and feed intake and a significant better feed conversion ratio in comparison with conventional feed. A explanation is not yet found . (This possible advantage has not been included in the calculation derived from table 6).|
|Phytase can also liberate zinc from phytate. This free zinc prevents absorption of cadmium [10,11].|
|Less feed phosphate such as monocalciumphosphate, dicalcium phosphate and monosodiumphosphate is needed. The production of these components is polluting (from the production process of phytase pollution information is not available).|
The investments by Gist-brocades have been very high. The exact amount is not available. In the pig and poultry industry, it depends on the form of phytase they use. When they use phytase in powder form the investments are nil. When the liquid form of phytase is used the feed factory had to invest in a spray installation which is adequate to deliver the liquid into the pellet accurately and homogeneously. This investment will be 40 to 50 thousands DFL (according to an estimation of Pre-mervo) . This investment is only necessary when during processing and pelleting the feed will be exposed to high temperatures. At high temperatures the phytase will be degraded. Using the spraying installation the phytase can be added after the processing and pelleting process maintaining all good properties. Cavo Latuco uses the powder form premixed by Pre-mervo .The farmer has no investment costs.
Operational and Maintenance Costs
The feed produced by Cavo-Latuco contains 0,3% Natuphos. This means a price increase of 0,05 to 0,20 DFL per 100 kg, depending on the animal species. A laying-hen requires the most expensive feed, it is 0,20 DFL per 100 kg more expensive when phytase is used and the P and the crude protein content are diminished. The most responsible for these expenses is the reduction of the crude protein content, and because of that the N-content in the manure .
Table 5: Technical data of a farm with fattening pigs .
|number of places for pigs||543|
|number of pigs present||500|
|feed conversion ratio (kg feed/kg growth)||2.80|
|energy conversion ratio (Energy Value/kg growth)||3.02|
|feed intake/animal/day (kg)||2.10|
|energy intake (Energy value/animal/day)||2.26|
|turnover speed/ average present pig||3.11|
|N-content (g/100 g feed)||2.61|
|K-content (g/100 g feed)||1.26|
|average energy content (Energy Value/kg feed)||1.078|
In the Netherlands the farmers can take advantage of the use of phytase, and in the future they will almost be forced to use it (in connection with the law) (FOOTNOTE: In the Netherlands the farmer has to pay for the manure excreted by pigs or poultry. When the farmer takes part in the MiAR (mineral supply registration system, he can reduce his costs with the help of phytase. In this system also the crude protein supply must be registered. In 1995 the farmers are obliged to produce 30% less phosphate (with regard to the lump standard.) When they cannot fulfill this they have to buy more quota or they have to reduce the quantity of pigs or poultry.)
For a fictional farm for fattening pigs an example is given in table 5, these data are the input for the following comparison. The start feed has remained the same with a content of 5 g P, the feed for fattening pigs differs in phytase and phosphor content. Fattening pigs feed 1 contains 0.3% phytase and 4.2 g digestible P/kg feed, fattening pigs feed 2 contains 0.0% phytase and 4.9 g digestible P/kg feed. This is a difference of 0.7 g P /kg feed. which is the same as 1.6 g phosphate /kg feed. For the calculation of the phosphate content a factor 2.29 is used. The fictional farm of table 5 is used to calculate the financial overview.
Table 6 : Financial overview with and without phytase (DFL) for fattening pigs .
|0.0% Natuphos (feed 2)||0.3% Natuphos (feed 1)|
|P-content feed (%)||0.49||0.42|
|P-surplus/total farm (kg)||1184||972|
|P-surplus/1000 kg growth (kg)||8.7||7.1|
|P-surplus/ average present pig (kg)||2.4||1.9|
|price feed DFL/100 kg||41.68||41.76|
|feed costs/annum/pig place||318.31||318.91|
|feed costs/delivered pig||102.35||41.76|
In table 6 it is clear that for a farm with the same conditions the feed with phytase is a little bit more expensive. How this works out in the costs per average present pig is also indicated. Using phytase a farmer has 0.52 (DFL) (per pig) more costs than without phytase. This results in additional yearly costs of 500 * 0.52 * 3.11 = 808 (DFL). In this example, which is a real in the Netherlands, about 20 % phosphate is reduced.
About the payback time of the production of the enzyme, no information is available. For the feed factory the investments where nil so the payback time is also nil. There is no experience yet with the nozzle system at the feed factory mentioned in this case study so data about the payback time for this system are not available.
The payback time for the farmer is not known because the costs for the excess quantity of P in the manure is not fixed yet.
|Feed factories have to control the temperature. The phytase is sensitive to temperature and moisture. This is a problem, especially with broiler feed .|
|When a high temperature is necessary during the feed production, liquid phytase can be used. This results in additional investments.|
Type of Source Material: Interviews, Annual reports, technical reports, technical journals etc.
Level of detail of the Source Material Some more technical detail is available. Information about experiments are available.
This case study was submitted to UNEP IE by the Institute for Applied Environmental Economics (TME) of the Netherlands on the part of the UNEP IE working group on Biotechnology. The case study was edited for the ICPIC diskette in August 1995.
Subsequently, in September 1998 the case study underwent a technical review by Dr. Prasad Modak, Environmental Management Centre, Mumbai, India.