Int’l - Enhanced animal feed will be a boon for the environment
Published:November 22, 2004
Source :CheckBiotech
Plant biotechnology is already making animal feed safer for a wide variety of livestock and holds even more promise for creating feed that is more nutritious and better for the environment.
Bt corn — enhanced with the naturally occurring soil bacterium Bacillus thuringiensis that wards off insect pests — already has lower levels of a harmful mold. And animal feed from this enhanced corn is considered healthier for both animals and humans.
But new animal feed being developed with plant biotechnology is expected to have even more benefits. Enhanced feed in development will allow animals to absorb essential nutrients in feed more efficiently, which will benefit the environment through a reduction in harmful wastes and will boost economic returns for farmers.
Phosphorus-rich corn
One way plant biotechnology is being used to improve animal feed is maximizing the way phosphorus, a critical nutrient for livestock, is utilized in feed.
Animals need phosphorous to grow, reproduce and to maintain healthy bones.1 Both corn and soybeans contain significant amounts of phosphorus in a form called "phytate." But swine and poultry lack the necessary enzymes required to digest phytate.
As a result, this undigested phytate passes through animals' digestive systems and can pollute lakes and rivers. At the same time, because the phytate can not be digested, livestock diets must be supplemented with expensive inorganic phosphorus to ensure proper health.
To help correct this imbalance, researchers at the University of Missouri–Columbia found that they can reduce the phosphorus waste from hogs by feeding them genetically enhanced corn that has lower levels of phytate and higher levels of digestible phosphorus.
In the low-phytate corn, 64 percent of the phosphorus was available to the animal, compared to only 10 percent availability with traditional corn. Additionally, the researchers found no adverse affects from feeding hogs the low-phytate corn.
"There is a tremendous increase in digestibility of phosphorus in the low-phytate corn," said Gary Allee, a swine nutritionist at the University of Missouri. "Low-phytate corn comes very close to supplying all phosphorus needs of a finishing pig."
Genetically enhanced feeds come just in time to feed a growing, more affluent global population that is consuming more meat. By 2020, it is expected that corn will surpass rice and wheat as the world's No. 1 crop.
Rising incomes in Asia and Latin America are triggering a shift to increased meat consumption, which in turn is creating more demand for corn-based animal feeds, according to the International Service for the Acquisition of Agri-biotech Applications (ISAAA).
Enhanced soybean meal
Corn isn't the only animal feed to be enhanced so phosphorous can be more efficiently absorbed.
A study published in the Canadian Journal of Animal Science looked at the effects of genetically enhanced low-phytate soybean feed on poultry. Researchers determined that the bioavailability of phosphorus in the low-phytate soy exceeded that of conventional soybean meal by 12 percent to 16 percent.
Another approach to reducing the levels of environmental phosphorus pollution is through the use of phytase, an enzyme that is added to animal feed to improve the absorption of phosphorous.
Its use is mandated in some countries such as the Netherlands — which has a tightly packed human population and a large hog-production industry — where the problem of phosphorus buildup has reached critical proportions. The enzyme can reduce the level of phosphorus released in animal waste to about half the previous level.
Although the enzyme is effective, it is also expensive — about three times the cost of conventional phosphorus supplements — and it degrades rapidly. Researchers at the University of Wisconsin are currently developing ways to genetically enhance alfalfa to provide the supplement more economically.
They have developed a strain of alfalfa that can express phytase, which can then be extracted from the juice squeezed from the alfalfa plants. Using plants as "bioreactors" to produce phytase — instead of the conventional method of using genetically enhanced organisms in fermentation vats to produce the enzyme — is believed to be more cost-effective.
In addition, initial tests have shown that alfalfa juice was effective in replacing inorganic phosphorus supplements in the diets of chicks.
Improved amino acid profile
In much the same way, plant biotechnology is also being used to improve the balance of essential amino acids in feed — lysine, methionine, tryptophan and threonine — so animals can more efficiently make use of protein.
Without the proper balance of these essential amino acids, much of the protein in feed can't be absorbed and is passed on as nitrogen in animal waste, which can also pollute lakes and rivers.
Boosting the levels of essential amino acids such as lysine, methionine, tryptophan and threonine would allow hogs and poultry to be fed lower-protein diets, according to Terry D. Etherton, professor of animal nutrition at Pennsylvania State University.
"Feeding these GM varieties to pigs and poultry would greatly reduce the amount of nitrogen … being excreted into the environment," Etherton said.
As safe as non-enhanced feed
Nearly 60 studies have concluded that biotech animal feed is as good or better for animals than their traditional counterparts, is more economical for farmers, and results in milk, meat and egg products that are identical to those produced from animals fed non-enhanced feed, according to a 2003 report from the Pew Initiative on Food and Biotechnology.
Currently, farm animals consume more than 75 percent of the U.S. biotech corn crop and a significant amount of the biotech soybean crop. The nutrients contained in this feed are nutritionally equivalent to their non-biotech counterparts, according to Barbara Glenn, the former executive vice president and scientific liaison for the Federation of Animal Science Societies (FASS).
Biotech corn has been on the United States and Canadian markets for several years and is also approved in Spain, the Philippinesand South Africa. These lion's share of the global biotech corn crop is used as animal feed.
"When you look at biotech corn — both grains and silage — you find there isn't any difference in protein, fat, fatty acids or carbohydrate components compared to conventional corn," added Glenn.
Jimmy Clark, a professor of ruminant nutrition in animal sciences at the University of Illinois at Urbana–Champaign reviewed the results of 23 research experiments that examined the differences between chickens, dairy cows, beef cattle and sheep that were fed biotech corn and soybeans and those that were fed non-enhanced varieties.
Each of the studies — conducted at universities in the United States, Germany and France — independently confirmed that there is no significant difference in the animals' ability to digest the genetically modified crops and no significant difference in the weight gain, milk production, milk composition and overall health of the animals when compared to animals fed the traditional crops.
In fact, more and more studies are showing that biotech corn is actually safer than feed made from conventional corn.
"There is now clear evidence that food and feed products from Bt corn are often safer than the corresponding products from conventional corn because of lower levels of the mycotoxin fumonisin," according to a November 2003 report from ISAAA.
