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Articles from 2012 In December

New study rebukes claims of allergic reaction to StarLink

New study rebukes claims of allergic reaction to StarLink

A paper published recently in the Journal of Allergy & Clinical Immunology reported that a 58-year-old man in Florida who claimed to have several reactions to food products that may have contained StarLink corn was not actually allergic to the biotech product.

Although StarLink caused quite a fervor when it was found in taco shells about three years ago -- having only been approved for feed use -- there have been no proven cases of allergic reactions to the now shelved corn variety.

The paper in the journal was authored by Drs. Steven A. Sutton, Amal H. Assa'ad and Marc E. Rothenberg and registered nurse Christine Steinmetz of the d

In their study, a double blind test was performed on the Florida man, who had complained of at least three allergic reactions to corn products that contained StarLink. The man

Two years ago, the Centers for Disease Control & Prevention had performed blood tests on the man -- and 27 others -- and noted that none demonstrated any

In a statement, the National Corn Growers Assn. (NCGA) said the new report reaffirms the safety of the U.S. food system and validates the credibility of the U.S. regulatory system.

"Even though this product didn't have any proven allergenicity, it was pulled from the market because of a regulatory procedure, demonstrating the extra regulatory scrutiny that biotech products come under," NCGA first vice president Leon Corzine said.

He noted the Starlink issue is a reminder of the importance of channeling. "It is important we make sure the products we produce stay in the markets where they are approved, and products are kept out of markets where they are not approved," he said. "This mistake (StarLink) cost literally millions to the American farmer. We must make sure it isn't repeated."

Volume:75 Issue:48

Cargill to expand Wagga Wagga beef plant

Cargill to expand Wagga Wagga beef plant

WAGGA WAGGA, AUSTRALIA -- Cargill Beef Australia announced recently that it will expand its beef processing facility here to better serve key customers, creating 125 additional jobs.

Construction will begin in January 2004 and is expected to be completed by March 2005. The expansion will increase the daily processing capacity to 1,200 cattle from 850. Employment would grow to 625 from 500.

"The increased capacity will be distributed to our dedicated customers in key export markets and here in Australia," said Dick Kelley, general manager of Cargill Beef Australia. "Woolworths, our key domestic account, will be a major recipient of our increased production."

Kelley said the upgrade will include a new meat-boning room, carcass sorting coolers, boxed-beef handling, chilling and freezing systems, as well as new environmental management systems. Already nearing completion is the installation of a biofilter designed to filter air coming from the plant. Capital will also be dedicated to new wastewater pre-treatment equipment.

"The announcement that Cargill will be commencing their long awaited redevelopment of its beef abattoir is the best possible news for our city," said Kevin Wales, Wagga Wagga mayor.

Cargill also announced that it has received planning approval to a proposed variation in the layout of the plant from the minister assisting the minister for planning and infrastructure. "This approval now enables Cargill to proceed with our revised upgrade," Kelley said.

Cargill acquired the processing facility in Wagga Wagga in 1991. Cargill Beef Australia also operates a beef facility in Tamworth, which opened in 1998.

Cargill Beef Australia is part of Cargill Australia Ltd., which established a presence in Australia in 1967 to serve the country's large grain exports and has since extended its involvement into several other agricultural industries including oilseed and beef processing, flour milling, as well as grain and cotton trading and grain storage.

Cargill Australia Ltd. is a wholly owned subsidiary of Cargill Inc.

Volume:75 Issue:48

Westland owners settle HSUS lawsuit

A settlement has been reached in which co-owners of the defunct Westland/Hallmark Meat Co. have agreed to make payments over the next five years totaling $316,802 to The Humane Society of the United States (HSUS) and the U.S. Government for their responsibility for animal abuse in 2008, according to an announcement by HSUS Nov. 16.

The judgment -- the largest court-awarded judgment ever for animal abuse -- cannot be collected because of the company's insolvency but sets a precedent to deter future incidents of animal cruelty, according to the announcement.

Meat producers "should take notice" that if they defraud the American people and U.S. government by abusing animals, "there will be serious consequences for their inhumane and reckless actions," said Jonathan Lovvorn, HSUS senior vice president and chief counsel for animal protection litigation.

An HSUS undercover investigator, four years ago, clandestinely filmed workers at Westland, a cull dairy cow processor, engaged in egregious animal handling practices in which workers tried to get non-ambulatory cows to stand to pass inspection to be processed (Feedstuffs, Feb. 4).

The company was the second-largest supplier of ground beef to the National School Lunch Program, and the video and the subsequent investigation by the U.S. Department of Agriculture prompted the largest meat recall in history and pushed the company into bankruptcy closure and liquidation.

The recall was based on the possibility that the actions of workers may have permitted tainted beef to enter the food supply.

HSUS, joined by the U.S. Department of Justice, brought litigation against nine owners of and/or investors in the company on the grounds that they had made "false claims" in misrepresenting their compliance with the lunch program that requires humane animal handling.

The judgment last week was against Donald Hallmark Sr. and Donald Hallmark Jr., who agreed to cooperate fully in the balance of the case by providing HSUS and justice department attorneys with documents pertinent to the matter.

USDA awards $4.5M in Farm to School grants


The U.S. Department of Agriculture (USDA) announced more than $4.5 million in grants for 68 projects, spanning 37 states and the District of Columbia, to connect school cafeterias with local agricultural producers.

The first-ever USDA Farm to School grants will help schools respond to the growing demand for locally sourced foods and increase market opportunities for producers and food businesses, including food processors, manufacturers, distributors. Grants will also be used to support agriculture and nutrition education efforts such as school gardens, field trips to local farms, and cooking classes. The grants will serve more than 3,200 schools and 1.75 million students, nearly half of whom live in rural communities.

The latest awards – 32 planning and 36 implementation grants – will reach over 3,200 schools serving 1.75 million American schoolchildren. USDA received 365 applications – 230 for implementation grants and 135 for planning grants – but is only able to fund a total of 18.6% of proposed projects, the National Sustainable Agriculture Coalition (NSAC) reported.

NSAC is calling on Congress to further farm to school programming through the farm bill.

Included in the Local Farms, Food, and Jobs Act, NSAC proposes flexibility in commodity programs that would enable more local food procurement in school meal programs.

While the Senate-passed bill includes a more general farm to school pilot program, the House Agriculture Committee-passed bill specifically authorizes schools with low annual commodity entitlement values to start making their own food purchases, provided USDA determines this would yield reduced administrative costs. Additionally, the House bill would create demonstration projects in at least 10 schools to test alternatives to USDA food distribution through farm to school procurement models.

“By increasing purchases of local farm products, schools provide lucrative market opportunities for farmers and ranchers, expand access to fresh foods for schoolchildren, and stimulate community economic development,” explained Helen Dombalis, NSAC policy associate. “The Farm to School Grants are a crucial step, and must be combined with legislation in the farm bill, in order to fully realize the economic potential of farm to school programs."


Modern domesticated turkeys genetically distinct from wild ancestors

Turkey dinners have become synonymous with Thanksgiving, but while the U.S. Department of Agriculture estimates that consumers cook and eat more than 45 million turkeys every Thanksgiving, very few people know much about the difference between their gravy-smothered poultry and the birds that earlier generations of Americans ate to celebrate the holiday.

"Ancient turkeys weren't your Butterball," said Rob Fleischer, head of the Smithsonian Conservation Biology Institute's (SCBI) Center for Conservation & Evolutionary Genetics. "We set out to compare the genetic diversity of the domestic turkeys we eat today with that of the ancestral wild turkey from southern Mexico. Some of what we found surprised us."

What an SCBI scientist and collaborators found was that the domesticated turkey that ends up on the dinner table exhibits less genetic variation than not only its ancestral wild counterparts, which were first domesticated in 800 B.C., but also than other livestock breeds such as domestic pigs or chickens.

The genetic traits affected by the variation are body size and breast muscle development -- features that can help determine the likelihood of a consumer buying a turkey. The results of the study were recently published in BMC Genomics.

"Few people know that the commercial turkeys served at Thanksgiving descended from Mexico, where they were discovered during the Spanish Conquest and transported to Europe," said Julie Long, senior author of the study and research physiologist with USDA's Agricultural Research Service in Beltsville, Md.

"During the next 100 years, Europeans created many different varieties of the domesticated turkey. It's important to assess the differences between ancient and modern domesticated turkeys in the event that some unforeseen problem might threaten the stability of the commercial turkey lines," Long added.

To obtain the results, the researchers sequenced the genomes of domestic turkeys from seven commercial lines and compared the genomes to those of three south Mexican turkey specimens collected in 1899 from Chihuahua, Mexico.

"It is often the case that selection in domestication reduces the level of variation," Fleischer said. "What did surprise us, however, is how well the ancient DNA from the three museum specimens worked to generate the genome sequences needed to determine the genetic variation and structure. These data and this approach show great promise for determining what genes were involved in the process of turkey domestication."

MFA releases video showing animal abuse at Butterball

Just a week ahead of Thanksgiving, Mercy For Animals (MFA) has released undercover video from "multiple Butterball farms" that MFA said shows workers engaged in abusive animal handling, dragging turkeys by their necks and wings, kicking and stomping on turkeys and "maliciously" throwing them on the ground and on top of other birds.

The video contains images like those of a previous undercover video at a Butterball farm near Shannon, N.C., that MFA released earlier this year showing workers engaged in similar animal handling (Feedstuffs, Jan. 9). That video led to criminal charges against and guilty pleas from workers who were identified in the film.

Butterball LLC is the largest turkey producer in the U.S.

The MFA news release, issued Nov. 14, quoted North Carolina State University veterinarian Dr. Greg Burkett as saying "the abuses" shown in the video are "identical" to those in the previous video, and he said the workers' behaviors "are cruel, inhumane and injurious to the birds."

He said he was "appalled at the disrespect these workers have toward other living creatures."

At the time of the previous video, Butterball trumpeted its animal welfare program, insisting that animal health and well-being is its "number-one priority" and that it has "zero tolerance" for mistreatment of turkeys.

In a statement following the latest video's release, the company reaffirmed that position, noting that its animal welfare program is based on standards that were developed by the National Turkey Federation in consultation with animal welfare experts Dr. Joy Mench at the University of California at Davis, Dr. Janice Swanson at Michigan State University and Dr. Gail Golab at the American Veterinary Medical Assn.

The company reported that it already has initiated an internal investigation and, after completing this investigation, will determine actions that should be taken, including termination of employees involved, both those who are found to have abused animals and those who witnessed abuse and failed to report it.

Animal care and well-being "are central to the operations of our company, and we remain committed to the ethical and responsible care of our turkey flocks," Butterball said in its statement.

MFA executive director Nathan Runkle said Butterball subjects turkeys "to horrific cruelty and violence" and the company should be held criminally liable for the actions of its workers.

The video, which contains disturbing scenes, can be viewed at www.ButterballAbuse.com. A narrator states that the video was filmed on Butterball farms in North Carolina and ends the video by urging viewers to "avoid animal abuse by choosing a vegetarian diet."

MFA, headquartered in Los Angeles, Cal., advocates vegetarianism.

Butterball, headquartered in Garner, N.C., is a 50/50 joint venture between Maxwell Farms LLC and Seaboard Corp.

Judge recuses himself from Beef Products-ABC case

A federal judge who was to handle the defamation lawsuit brought by Beef Products Inc. against ABC News has recused himself from the case, removing himself out of the case on Nov. 20.

Judge Lawrence L. Piersol did not explain why, and the case has been reassigned to Judge Karen Schreier. The trial will be handled in the U.S. District Court for the District of South Dakota in Sioux Falls, S.D.

Beef Products, headquartered in South Sioux City, Neb., filed its suit in September, alleging that ABC's coverage of Beef Products' main product, lean finely textured beef (LFTB), was intentionally and knowingly false and disparaging (Feedstuffs, Sept. 17).

The coverage, which began in March and lasted over several weeks, cast doubt on the safety and wholesomeness of LFTB, which is a beef product that's mixed with ground beef to increase leanness and keep prices to consumers down.

Beef Products said the coverage had significant adverse financial impact on the company, forcing it to close three of its four plants and lay off several hundred employees.

The company is seeking $400 million in damages, which can be tripled under state law regarding the defamation of agricultural products.

ABC subsequently asked the court to dismiss the suit on the grounds that it seeks to inhibit press freedom (Feedstuffs, Nov. 5).

House approves Russia trade normalizing bill

The House of Representatives passed H.R. 6156, the Russia and Moldova Jackson-Vanik Repeal Act of 2012, in a bipartisan vote, 365-43. This bill ensures that U.S. agricultural producers can benefit from Russia's membership in the World Trade Organization (WTO) by establishing permanent normal trade relations (PNTR).

As a condition of joining the WTO, both countries have agreed to reduce their trade barriers, enforce intellectual property rights, and abide by international trade mediation. By officially removing an outdated legal barrier, H.R. 6156 will allow the United States to begin taking advantage of increased trade and export opportunities in Russia and Moldova. The legislation also contains provisions intended to address human rights concerns in Russia due to the death of whistleblower Sergei Maginsky in 2009.

The action now sets up approval in the Senate, where the Senate Finance Committee unanimously approved the measure earlier this year.

House Agriculture Committee chairman Frank Lucas, (R., Okla.) said he is pleased that the two countries will finally be trading on a level play field after years of U.S. exporters facing "arbitrary and unpredictable market barriers in the Russian market."

Lucas added that U.S. agricultural exports to Russia exceeded $1.5 billion in fiscal year 2012 and the action will provide additional value and increased access into a growing market through lower tariffs and more certain trade rules.

In a statement from Rep. Steve King (R., Iowa), he said exports to Russia could double or triple within five years as it reduces its tariffs and trade barriers on goods and services.

California egg farmers file Prop 2 suit

The Association of California Egg Farmers (ACEF) has asked a California court to enjoin enforcement of the law that the state's voters approved in 2008 regarding housing for hens and other farm animals.

The law, which was listed on the 2008 ballot as Proposition 2, or "Prop 2," requires that all farm animals, "for all or the majority of any day," not be confined or tethered in a manner that prevents them from lying or sitting down, standing up, turning around or fully extending their limbs without touching another animal or an enclosure such as a cage or stall.

Prop 2, which passed with 63.5% of the statewide vote, becomes effective Jan. 1, 2015 (Feedstuffs, Nov. 10, 2008).

In its court filing, ACEF said the Prop 2 language clearly means that California egg producers must change the kind of housing that they currently have in place, i.e., conventional cage housing, but provides "no ascertainable guidance" as to acceptable densities and dimensions of the enclosures that should be adopted.

ACEF noted that the California egg industry houses 19 million hens and that egg producers will need to remodel or replace their housing within the next two years at an estimated cost of $400 million.

Without any specification as to Prop 2's requirements, it's "untenable" for producers to arrange for that financing and make that investment, ACEF said.

Accordingly, to avoid what could be wasted spending, as well as potential criminal prosecution and fines, many producers will likely close down their farms, forcing the euthanasia of millions of hens. "The continued viability of the California egg industry is in jeopardy," according to the organization.

Prop 2 carries penalties of up to 120 days in jail and fines of up to $1,000 per violation.

ACEF referred the court to pending federal legislation that would establish a national standard for hen housing with specific density and space per bird. The legislation is being pursued by The Humane Society of the United States (HSUS) and the United Egg Producers through a joint agreement (Feedstuffs, July 11, 2011).

HSUS was the main proponent of Prop 2.

Two earlier California court challenges to Prop 2 have failed.

ACEF filed its complaint in the Fresno County Court and named California Attorney General Kamala Harris as defendant.

Managing feed nutrients to benefit environment will be major challenge

Managing feed nutrients to benefit environment will be major challenge

Dr. William A. Dudley-Cash is a poultry and fish nutritionist and has his own consulting firm in Modesto, Cal. To expedite answers to questions concerning this article, please direct inquiries to

The accumulation of nutrients in soils and the concurrent threat to surface water quality as the result of runoff or leaching of these nutrients is a major challenge facing animal agriculture. The U.S. Environmental Protection Agency has determined that more than 20% of the streams and rivers in the U.S. have been affected by non-point source pollution and has identified animal agriculture has one of the contributors.

The effect of nutrient accumulation in soils as the result of the application of animal manure has been evaluated using the nutrient balance approach. Annual applications of nutrients are offset by the amount of nutrients removed from the soil through crop production. Early estimates assumed that nitrogen accumulation would be a primary problem in the application of poultry litter to farmland. The application of poultry litter would be limited by the amount of nitrogen removed in crop production. However, soil balance studies and experience have shown that phosphorous accumulation is probably the more serious problem.

R. Angel of the University of Maryland presented a paper at the California Animal Nutrition Conference in which she reviewed the role of phosphorous and environmental nutrient accumulation. Phosphorus is present in most poultry feeds at relatively high levels. Only calcium and nitrogen are present at levels higher than total phosphorous. Much of the phosphorous in poultry feeds is poorly utilized. Most crops do not harvest large quantities of phosphorous from the soil. This combination of factors contributes to the importance of phosphorous accumulation in the soil.

Angel reviewed the recent national efforts to minimize losses of particulate and soluble phosphorous from soil to water. These efforts include the Unified National Strategy for Animal Feeding Operations, developed cooperatively by the U.S. Department of Agriculture's National Resources Conservation Service and EPA, and the National Nutrient Strategy adopted by the Natural Resources Conservation Service in 1999.

In Delmarva, new legislation limits the use of litter application to soil (based partly on soil phosphorous content). Legislation in Maryland requires that all poultry feeds contain phytase or other feed additives that decreases phosphorous excretion. With limited land areas for litter application, the poultry industry must find strategies that reduce the phosphorous levels in litter with the least impact on the economics of production. Sooner or later, the challenge of minimizing the excretion of phosphorous will have to be faced by the poultry industry nationwide, according to Angel.

A major part of the Angel presentation was focused on the chemical form(s) of phosphorus in poultry feeds, the factors that affect the biological utilization of this phosphorus and how these relate to the excretion of phosphorus in the litter.

Phytic acid, phytate, phytin

Angel discussed the importance of phytin phosphorus (PP). Phytic acid is a phosphorylated cyclic sugar alcohol, (phosphorylated inositol). Phytate is the anion form of phytic acid. Phytin is the chelated form of phytate. The phosphorous content of phytic acid is 28.2%.

Phytin is the primary storage form of phosphorous in plants. Plant roots contain low amounts of phytin, and vegetative parts of plants (such as the leaves) contain only trace amounts. Most of the phytin is located in the seeds.

The storage location of phytin in the seed varies among species of plants. Ninety percent of the phytin in corn is found in the germ of the kernel. In the case of wheat and rice, most of the phytin is in the aleurone layers of the kernel and the outer bran. In the case of most oilseeds and grain legumes, the phytin appears to be distributed throughout the kernel. Phytin constitutes between 1 and 3%, by weight, of many of the cereals and oil seeds used in animal feeds.

PP accounts for approximately 50-80% of the total phosphorous present in plant feed ingredients. The phosphorous in phytin is not available to monogastric animals (or any other animal) until a phytase enzyme has released it. Phytase enzyme may be naturally present in plant feed ingredients. Bacteria in the intestinal tract may produce phytase enzymes (rumen bacteria produce a lot of phytase). Phytase enzyme may be present in the lining of the intestine. Phytase enzymes may be added to the feed as exogenous sources. The phytase enzyme must come from someplace.

There are adequate levels of total phosphorous in most plant feed ingredients to meet the dietary requirements of most animals, provided that PP is released from the phytin molecule so that it becomes available to the animal. However, in general, monogastric animals poorly utilize PP. PP in feed that is not released, and therefore not utilized, becomes the phosphorous that is excreted and potentially accumulates in the environment.

Phytin is often referred to as anti-nutritive because of its ability to chelate cations in the diet, which renders these chelated cations partially or completely unavailable to the animal. At all pH values normally encountered in feeds and digesta, phytin will carry a strong negative charge and is capable of binding di- and trivalent cations including calcium, cobalt, copper, iron, magnesium, manganese, nickel and zinc.

The phytin forms very stable complexes reducing the availability of these minerals to the animal. Phytin also forms complexes with proteins and starches. The binding of phytin with proteins and starches may also reduce the availability of these nutrients.

PP utilization

Most recent studies with chickens show that PP utilization is variable. Dietary factors may influence the hydrolysis of PP in the intestinal tract. These dietary factors include the levels of calcium, non-phytin phosphorous, total phosphorous and vitamin D as well as feed processing and feed ingredient particle size. PP utilization by chickens is reported to be as low as zero to 15% by some researchers and as high as 70-75% by others. Ballam et al. (1984) reported PP hydrolysis in four-week-old female broilers ranged from 3 to 42% and depended primarily on dietary calcium level.

The effect of high levels of calcium on intestinal pH may be partly responsible for some of the deleterious effects that high dietary calcium has on PP hydrolysis. High dietary calcium concentration (2.53 versus 1.07%) was reported to increase the pH in the crop (5.32 versus 4.89) and ileum (7.39 versus 6.62; Shafey et al., 1991). The pH of the contents of the gastrointestinal (GI) tract increased as the digesta moved distally, starting at the proventriculus. Digesta pH in birds fed 1.07% calcium was 4.89 in the crop, 1.98 in the proventriculus, 3.14 in the gizzard, 5.53 in the duodenum, 6.06 in the jejunum, 6.62 in the ileum and 6.48 in the ceaca.

The increased pH of the GI contents causes the PP molecule to be ionized and thus more readily forms complexes with divalent metal cations like calcium, zinc, magnesium and iron. These complexes, at high pH, are less soluble. Solubility is an important factor in the overall utilization of PP because phytase cannot act efficiently on PP unless it is in a soluble form.

PP hydrolysis

The degree to which PP is utilized by the animal will depend to a large extent upon its hydrolysis in the GI tract. The hydrolysis of phytin by phytase occurs when phytin is in solution. When phytin chelates with calcium and other cations, it may form soluble complexes, especially at lower pH. However, as the pH increases, these complexes precipitate as insoluble complexes at the higher pH found in the lower intestinal tract. These insoluble complexes reduce the ability of phytase to hydrolyze the chelated complex, thus decreasing the availability of both PP and the cations associated with this insoluble complex.

When the dietary calcium and phosphorous concentrations are increased, the proportion of chelate complexes that precipitate also increases. The solubility of calcium was found to be 16.9% when the calcium and available phosphorous levels were 1.53 and 0.53%, respectively. The solubility of calcium was only 8.3% when the levels of calcium and available phosphorous were increased to 2.26 and 0.83%, respectively. Increasing the dietary calcium and available phosphorous levels reduced the proportion of soluble minerals and thereby further decreased the availability of these minerals.

The inhibitory effect of high levels of calcium on PP hydrolysis can be prevented or reduced by the addition of a calcium chelator like ethylene di-amine tetra acetate (EDTA). The mode of action of EDTA may be that it is competing with phytin to bind with calcium, thereby preventing the precipitation of the phytin-calcium complex.


Phytases are enzymes that are able to catalyze the hydrolysis of the phosphate ester bonds of phytin. The action of phytases ultimately leads to the production of inorganic phosphorous and free myo-inositol. Phytases are widely distributed in plants, animals and microorganisms. IUB currently acknowledges two general classes of phytase enzymes: 3-phytases and 6-phytases. These phytases initiate the hydrolysis on the 3 and 6 position of the inositol ring, respectively.

Wodzinski and Ullah (1996) reported that the 3-phytases do not always completely dephosphorylate phytic acid while the 6-phytases do. It has been reported that microorganisms normally produce 3-phytases while 6-phytases are usually found in plants. However, exceptions to this general rule have been discovered.

According to Angel, there are four possible sources of phytases that could be found in the intestinal tract of animals: (1) phytases present in feed ingredients, (2) exogenous microbial phytases added to the feed, (3) phytases produced by endogenous microflora in the intestinal tract and (4) membrane-bound phytases in intestinal mucosa.

Microbial phytases tend to have pH optima in the range 2-6, while plant phytases tend to have a pH optima at 5. Most research indicates that all sources of phytases have phytate hydrolyzing activity. However, it is also clear there is a wide range of activity from one experiment to the next. The difference in activity may be related to the source of phytase or the composition of the experimental diets.

It would appear that microbial phytase, with a wider range of pH optima, may have an advantage. With pH optima near 2, the microbial phytases would be active in the proventriculus and gizzard where phytin tends to be most soluble and therefore available for enzyme action. Plant phytases, with pH optima near 5, would be most active in the small intestine where phytin tends to be insoluble and therefore not accessible for hydrolysis.

In addition, the plant phytases, like those that are found in different varies of wheat, may be largely denatured by the low pH encountered in the proventriculus, or destroyed by protease enzymes, before they reach the small intestine.

Using models

Estimation of nutrient excretion based on models has become necessary due to the recent emphasis on environmental management and regulation of animal feeding operations that rely on the prediction of nutrient excretion. As federal, state and local regulation increases in the nutrient management arena, the accuracy of these nutrient excretion models is imperative. Angel discussed two of these models.

The National Research Council (NRC; 2003) model is based on a process-base mass balance approach. Excreted nitrogen is calculated by subtracting the quantity of nitrogen produced in the animal from the quantity of nitrogen consumed in the feed. This model assumes broilers are fed to meet NRC (1994) nutrient recommendations, and this model uses bodyweight and feed efficiencies as given in the NRC (1994) bulletin.

The NRC (2003) model, thus, is using broiler information published between 1942 and 1990 for amino acid requirements and between 1952 and 1983 for phosphorous requirements. There clearly are differences in efficiency in nutrient use, growth and skeletal development between current broilers and those of more than 10 years ago.

A model developed by Applegate et al. (2003) bases nutrient excretion on industry average feed formulation and average performance. The primary nutrients estimated are nitrogen, phosphorous and dry matter. The model may be used to calculate manure nutrient excretion per bird to market weight, based on average diet formulation, average performance and average published dry matter, nitrogen and phosphorous retention for broilers, turkey males, turkey hens, ducks and laying hens.

A balance trial was conducted with broilers (Angel et al., 2003) to validate the model developed by Applegate et al. (2003). The results of the balance trial indicated that the model over-estimates dry matter, nitrogen and phosphorous excretion by approximately 19.4, 14 and 13%, respectively.

While modeling programs are necessary in order to provide information that is not available from direct experimentation, it is essential that the components for feed formulation, bird genetics and bird performance be continuously updated to reflect current production.

Calcium, phosphorus in feed

An area that Angel emphasized in her oral presentation was the importance of feed components and feed formulation on the reduction of excreted phosphorous. It is clear that reduced levels of phosphorous and especially calcium can improve the utilization of PP and consequently reduce the levels of excreted phosphorous as well as reduce the need for supplemental inorganic phosphorous. It may be possible to reduce the levels of calcium and total phosphorous in the diet to the extent that the addition of inorganic phosphorous is not necessary, even in the absence of supplemental phytases (at least in finisher feeds).

With the growing importance of excreted phosphorous, this area clearly requires more careful evaluation.

The original paper in the proceedings is 15 pages long and contains 62 references. For the serious nutritionist, this is an excellent paper, and the reference list alone justifies the cost of the proceedings.

The Bottom Line

The poultry industry eventually will have to face the challenge of minimizing phosphorous excretion (and probably other feed nutrients). The total phosphorous content of most poultry diets would be adequate to meet the phosphorous requirement if all PP were utilized. The levels of total phosphorous and calcium that are contained in the diet significantly impact the availability of PP.

The nutritional requirements for calcium and phosphorus may be lower than the levels provided in current commercial feeds. Reducing the levels of these nutrients will reduce their excretion in the litter. In addition, reducing the levels of calcium and phosphorus will increase the utilization of PP. Careful adjustment of the total phosphorous and calcium levels may allow the industry to significantly reduce the amount of phosphorous excreted into the litter while maintaining economic performance.


Copies of the proceedings of the California Animal Nutrition Conference may be obtained ($20 each) by contacting Ann Quinn, California Grain & Feed Assn., 1521 I St., Sacramento, Cal. 95814; phone, (916) 441-2272 or fax, (916) 446-1063.

Volume:75 Issue:27