Phytase Sources Is There a Difference

bonderic

One phytase product claims an advantage in heat processing; the other claims an advantage in efficacy. Is one better than the other?
Unit for unit, the spelling is different, but the two most popular phytase products base enzyme activity on the same standard of measurement.
Natuphos, marketed by BASF Animal Nutrition, is measured in FTUs. The product is made from Aspergillus niger fungi and is a 3-phytase, meaning the phosphates are released from the phytate beginning at the carbon-3 of the inositol ring. The product is active over a wide range of pH from 6.5 to 5.5.
Ronozyme P, marketed by Roche Vitamins Inc., is measured in FYTs, after the Danish spelling of phytase. It is produced using the organism Peniophora lycii and is a 6-phytase product. Ronozyme is active over a narrower pH range, with an optimum of 4.5.
Regardless of the source, phytase research shows optimum supplementation of 227 units of phytase per pound of feed replaces about 0.1% available phosphorus in a corn-soybean meal ration.
Phytase lowers the phosphorus excreted in manure by releasing the phytate-bound phosphorus found naturally in grains and soybeans. Like poultry, swine lack sufficient intestinal phytase. By adding the enzyme to the diet, more phosphorus becomes available to the animal, which lowers the amount of supplemental phosphorus required and the amount that goes undigested. About 11 to 12 lb. of inorganic phosphorus can be substituted with 0.4 lb. of phytase product per ton of feed.
Phytase Interest GrowingThe interest in phytase is growing quickly with the trend towards phosphorus-based manure management. An early adopter, Heartland Pork Enterprises has been adding phytase in their late nursery through grow-finish rations for almost two years.
“As a company, we take environmental stewardship seriously,” says Keith Haydon, director of nutritional programs for Heartland in Alden, IA. “We are phosphorus-based, company-wide, even though it is not mandated by the state. Last year we showed a 23% reduction in manure phosphorus, which means we have decreased the acreage we need by a quarter.”
Heartland uses phytase on a least-cost basis, formulating diets according to available phosphorus. They use Natuphos 5000L, adding 0.2 lb./ton in a post-pelleting liquid application system. The high temperatures used in pelleting can denature the phytase enzyme, so the company uses a spray-on liquid form. According to Haydon, most degradation occurs at temperatures of 180° F. or above.
Roche spokesman Jon Wilson, technical marketing director, says heat stability is one area where Ronozyme may have an advantage over other phytase products. Kansas State University trials showed 88% of the phytase from granular Ronozyme survived 194° F. temperatures.
The CT form of Ronozyme is coated with a wax to protect it from heat during pelleting. Chemically thermal tolerant (CT), this dry form of phytase has been on the market about five months in the United States. On a price per unit of activity, Wilson says, the cost is less than $1/ton to replace 0.1% available phosphorus.
Phytase ComparisonA University of Nebraska study looked at differences in performance between the two dry phytase sources in a corn-soybean meal diet added pre-pelleting. Temperature of the pellets ranged from 150° to 160° F., cooler than most mills, notes University of Nebraska researcher Mike Brumm.
Phytase recovery following pelleting ranged from 74% to 100% for the two products. There was no effect of phytase source on daily gain, feed intake, carcass lean, bone ash or the more sensitive measure of bone-breaking strength, indicating adequate phosphorus in the diet. Pigs fed Ronozyme had improved feed conversion over pigs fed Natuphos.
Phytase awareness is coming fast, says swine specialist Brumm. New federal regulations are expected this winter governing soil phosphorus. Some states are already implementing regulations of their own.
Maryland requires the use of phytase in livestock feed. Iowa recently passed legislation requiring any animal operation with more than 500 animal units to have a phosphorus-based manure management plan.
Nebraska requires manure plans for all approved sites with 300 or more animal units, which includes mandatory phosphorus reporting. Samples must be taken on 40-acre grids and if soil phosphorus in the 6-in. sample is above 150 parts per million (ppm), results must be reported to the state. “They do a case by case judgment on whether manure can be applied to that grid,” says Brumm.
Although both products proved effective, producers have been slower to adopt Ronozyme, he adds. Natuphos comes in a 50-lb. bag and currently is easier to add in a ton of feed on the farm. Ronozyme must be preblended, although large users have been able to incorporate it into their systems.
Differences in pHBecause of its wider pH range, BASF spokesman Mike Coehlo says Natuphos releases 1.5 times more phosphorus than its competitor. This is because Natuphos is more active over the pH range found in the digestive tract, he explains. And the increased bioactivity means more phytate is released into the digestive tract.
Does pH range make a difference? “We don't know,” says Purdue swine nutritionist Scott Radcliffe. “An enzyme with an optimal pH closest to that found in the stomach should have an increased efficacy, since the stomach is the major site of activity for dietary phytase. However, little research has been conducted to determine phytase activity in the stomach, and the pH of stomach contents during the time the enzyme is active. Therefore, most measures of phytase efficacy in comparison trials rely on indirect measurements of activity, such as growth performance and bone mineralization.”
Radcliffe says the majority of phytase comparison trials have studied phytase sources in broilers. While broilers may give an indication of the relative efficacies of phytase products, it should not be assumed that this data can be directly extrapolated to the pig, he says.
“Some research, including some from our laboratory, has suggested that there is a difference in the efficacy of commercially available phytase products. However, this difference is small enough to require that economics — the cost per ton of feed — be figured into the decision,” he says. “The good news is that the competition has helped keep phytase prices down. In fact, the enzyme is cheaper than it was a year ago.”
From a practical/production standpoint, the relative efficacy of phytase products on a per unit basis is not that important, continues Radcliffe. What is important is the cost of each product per ton of feed to achieve similar results and performance.
Radcliffe also feels the degree of over-formulation of phytase products needs to be scrutinized. A company might have 30-60% overage in the hot summer months to make up for instability due to heat, he says. The excess supplementation can skew any performance differences in the field, making up for differences in efficacy.
According to BASF's Coelho, director of marketing in the animal nutrition division, that's not a fair game to play. “The phosphorus safety margin formulated in diets by industry nutritionists should not be used by phytase suppliers to make up for the lack of bioefficacy.”
Product DifferencesNatuphos G is offered in a wide range of concentrations. There are five potency levels — 600, 1,200, 2,400, 5,000 and 10,000 FTU/g. Adding 1 lb. of 600 FTU/g. to 0.1 lb. of 10,000 will provide the recommended level of phytase.
Ronozyme P (CT) is less concentrated at 2,500 FYT/g. and is added at 225 FYT/lb. for a mash (0.4 lb./ton) and 340 FYT/lb. (0.6 lb./ton) for pellets, to ensure 227 FYT is provided to the pig.
A third phytase, Allzyme, is made by fermentation using Aspergillus niger fungi. The 3-phytase product isn't as pure as Natuphos and Ronozyme, but contains additional activities which may be beneficial, particularly in non-corn-soybean meal based diets, according to Radcliffe. Similar to Natuphos, it has a wide range of pH activity. Manufactured by Alltech, Allzyme is not widely used in the U.S.
“Up to this point,” says Radcliffe, “the data out there is a mixed bag. Hopefully more swine data will be available in the future.”


[ts]bonderic 于 2009-7-15 17:53 補充以下內容[/ts]

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