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New Challenges in Intestinal Health Management

Growing flocks without in-feed antibiotic growth promoters (AGPs) has had its consequences. One is an adverse impact on intestinal health, which has contributed to the multifactorial disease known as necrotic enteritis (NE). Until their use was discontinued, the contribution of AGPs to the control of NE was not fully appreciated.

The ban on AGPs was implemented due to concern that subtherapeutic antibiotics given in poultry and livestock feed may contribute to antibiotic resistant infections in people, but it has resulted in more infections and, ironically, has increased use of therapeutic antibiotics, underscoring the need to find non-antibiotic alternatives.

The importance of NE cannot be underestimated. As nutritionist Bill Dudley-Cash recently wrote in Feedstuffs, an internationally read trade publication, "The successful commercial production of [poultry], in the absence of antibiotics, is dependent on the control of necrotic enteritis." An increasing number of poultry consumers worldwide are demanding that their broilers be grown without in-feed antibiotics and "understanding, controlling and/or managing necrotic enteritis are the keys to growing chickens without antibiotics," he said.

Dr. Luciano Gobbi, technical service manager for Schering-Plough Animal Health in Italy, says that NE can be controlled without routine, subtherapeutic antibiotics, enabling producers to move a huge step toward meeting consumer demand for truly antibioticfree poultry.

Gobbi points out, however, that NE goes hand-inhand with another enteric disease - coccidiosis - which damages the intestinal lining, setting the stage for the overgrowth of Clostridium perfringens - the cause of NE. "Good control of necrotic enteritis requires good coccidiosis control," he says.

The quest for antibiotic alternatives for control of necrotic enteritis as well as coccidiosis has focused largely on nutrition, management and vaccination. To further knowledge in the poultry industry on these topics, Schering-Plough Animal Health recently organized a seminar near Venice. More than 100 representatives of leading poultry companies from Europe, the Middle East and Africa gathered to hear from experts on non-antibiotic control of intestinal disease. Participants also had the opportunity to hear from several producers who are successfully controlling coccidiosis with vaccination and from a marketing expert about how to succeed in today's climate.

CocciForum magazine is pleased to present highlights from the seminar in the articles that follow.

Future approaches for necrotic enteritis control

Davis: 'When we talk about necrotic enteritis, we have to talk about coccidiosis control.'

Necrotic enteritis has become a leading problem for broiler chicken producers, but control of the disease is possible with a combination of vaccines and microflora modulation, predicted Dr. Steve Davis, president of Colorado Quality Research, Inc., a US-based poultry research company.

In recent poultry industry surveys, necrotic enteritis was one of the top five health problems affecting broiler flocks, said Davis. "It's very much a hot topic... and it did not become a problem until we started trying to raise broilers without in-feed antibiotic growth promoters."

Davis's organization has conducted between 30 and 40 studies of necrotic enteritis and made several interesting observations. One is that the cause of necrotic enteritis - the alpha toxin produced by Clostridium perfringens - varies widely.

"There's a real difference in the C. perfringens out there," he said. With some isolates, just a little administered in feed will rapidly kill birds. Other C. perfringens isolates tend not to cause mortality, but adversely affect weight gain and feed conversion.

"When we talk about necrotic enteritis, we have to talk about coccidiosis control," he continued. It's much easier to induce necrotic enteritis if birds have coccidiosis, particularly the Eimeria maxima variety. Coccidiosis damages the intestines, providing the right environment for C. perfringens to proliferate and for NE to develop.

Ionophore anticoccidials such as lasalocid, monensin and salinomycin have antibacterial properties - more than people realize, he added. "We feel very strongly that ionophores have helped prevent necrotic enteritis not by control of coccidiosis, but because they have actual [antibacterial] efficacy against C. perfringens," Davis said.

Ionophores, however, are probably on their way out due to public pressure to eliminate the use of all antibiotics in food animals. Chemical anticoccidials have no antibacterial effects and therefore would do little to control NE, said Davis.

Considering the current situation, vaccines are the direction of the future for coccidiosis control and may be used alone or in rotation with any anticoccidial to help prevent drug resistance, he said.

Besides coccidiosis, other factors that appear to predispose flocks to NE are poor chicken quality and uniformity. "We've noticed if chicks are of poor quality, we have more necrotic enteritis mortality and more early mortality," he reported. "The more uneven the birds are, the easier they succumb to a C. perfringens challenge. It's always the smallest chicks that end up being the first to die."

In addition, faster growing birds also tend to break with necrotic enteritis sooner than slower-growing birds, he said.

"When you get an ideal flock, it's very difficult to produce necrotic enteritis," Davis said, adding that it's possible that some breeds of birds are more resistant to the disease.

Control of NE in the future may depend largely on vaccines, partly because the C. perfringens bacterium has excellent potential for use as a vaccine antigen, he said.

Schering-Plough Animal Health has developed a C. perfringens type A toxoid vaccine for NE that is currently being used in the United States. (See www.netvaxforpoultry.com.) In 2008, it is expected to be approved for use in Europe.

Davis pointed out that while the new C. perfringens type A toxoid may be new for poultry, the technology is not new among sheep, cattle and swine. Because injecting individual broilers would be impractical and costly, the toxoid is given to breeder hens, which then convey passive immunity to their broiler progeny, he said.

Davis's company tested the toxoid in broilers that also received a coccidiosis vaccine for coccidiosis control. Birds with passive immunity from hens that had received the NE toxoid had a significant decrease in NE lesions and a numerical decrease in mortality compared to birds not from hens that received the toxoid. (Figure 1.)

"Passive immunity through vaccination definitely shows that it has excellent potential" for control of NE, Davis said.

To further prevent and control the disease, "We have to avoid placing known poor quality chicks on farms that we know have a high C. perfringens challenge or repeat necrotic enteritis farms," he advised.

Improved cleaning and disinfection programs may help control NE if ways can be found to kill C. perfringens spores but not the "good bugs" in the house, Davis added.

Figure 1. Necrotic enteritis mortality "vaccinates vs. challenged and non-challenged controls.

A = Challenged control
B = Non-challenged control
C = Chicks from hens not given clostridium toxoid and vaccinated day 1 for coccidiosis
D = Chicks from hens given clostridium toxoid and vaccinated day 1 for coccidiosis

Davis has found that diet definitely can influence NE. The more wheat, rye and barley fed to chicks, the greater the toll of NE. High protein levels have been associated with NE outbreaks. Animal byproducts, particularly fishmeal, may be contaminated with clostridium. Consider that successful antibiotic-free poultry producers in the United States tend to use all vegetable diets, he said.

"I'm not saying we have all the answers, but it's quite obvious that we can play with these diets and create necrotic enteritis," he said. Davis has also studied feed additives including enzymes, probiotics and organic acids. "We have not found anything that I would say is a magic bullet."

Nevertheless, "as we learn more about the natural microflora of the gut, we're going to get better and better with these types of products. When combined with vaccine technology, we're going to find that it may be possible to prevent NE without antibiotics," he said.

Maximizing intestinal health with nutrition

ten Doeschate: 'Chicks need to develop a healthy, wellfunctioning gut early in life.'

Nutrition can maximize intestinal health and help prevent enteric disease, but deciding which ingredients to use and finding the right balance of each can require as much finesse as a high wire act.

The trend toward growing broilers with fewer or no in-feed antibiotics is forcing producers to consider an array of dietary approaches that may or may not improve intestinal health and prevent "dysbacteriosis" - an overgrowth of "bad" gut bacteria, said Dr. Rob ten Doeschate, a poultry nutritionist with Abnatech Global, Peterborough, England, a consulting and research firm serving the poultry industry.

"We used to have antibiotic growth promoters (AGPs). They're gone. We're still using anticoccidials in the feed and one by one the list of available anticoccidials gets shorter, so vaccines will need to be used," he said.

To help ensure good intestinal health in light of current trends, it's more important than ever to begin by making sure broiler chicks get off to a good start, ten Doeschate said.

"Chicks need to develop a healthy, well-functioning gut early in life, so for the first week, feed very high nutrient and mineral levels," he said. The digestible levels of amino acids may be above breed standards. Sodium is key, "but don't forget calcium and phosphorous," he added.

The diet should also have a good physical quality to ensure intake and stimulate gut development. "Nowadays we use good quality fat and oil almost exclusively," he said. Too much fat, however, is bad because lipid digestion is still underdeveloped.

Young birds need highly digestible protein. "I don't think that's soy, so I like to see a bit of fish meal and, if you can't use fish meal, use some other purified protein to help the bird the first couple of days," ten Doeschate said.

The nutritionist believes that better intestinal health can be promoted by encouraging gizzard development, which can be accomplished by incorporating some coarse material, such as whole wheat, into the diet.

In the United Kingdom, whole wheat is widely used in broiler feeding. Wheat has been linked to an increased risk for some intestinal problems but, according to ten Doeschate, the key is finding the right amount, which can be challenging.

Feed trials comparing no wholewheat dilution with medium and high levels of added wheat showed that a high level of wheat resulted in decreased live weight and poor feed conversion, but it also resulted in a lower water intake and fewer hock lesions. Medium amounts of whole wheat addition can be positive, ten Doeschate has found.

Wheat-based diets do result in increased gut viscosity, "and we use NSP (non-starch polysaccharide) enzymes to get over that," ten Doeschate said.

Besides enzymes, there are several other "pronutrients" or additives to consider for broilers raised without AGPs, he said.

One option is acid salts or organic acids, which have been used extensively in breeder feeds to eliminate or control salmonella. In broiler chicks, their benefits are not as clear. Trials at Abnatech have shown that birds tend to drink more if there's a lot of acid in the feed, complicating litter management. "In addition, free acids are corrosive and therefore are not popular at feed mills; acid salts are probably less effective and aren't really the product for poultry either," he said.

Plant extracts such as essential oils have been touted as an alternative to antibiotic growth promoters, but questions remain about their active ingredients and quality. "If you get a level in the diet that will work, it might be so high that we can't afford it, so it's not one we've used," ten Doeschate said.

Prebiotics are another option and would include complex carbohydrates such as mannan oligosaccharides from yeast cell walls. Yeast products, he said, have performed well in trials. They are not digested by the bird and improve gut health. Mannoproteins prevent attachment of Escherichia coli and other bacterium to the gut wall and stimulate the immune response, he said.

The nutritionist is also big on betaine, which is an "osmoprotectant" that helps maintain cell integrity. Studies show that in chickens with coccidiosis, where the ratio between crypt depth and villi length decreases, betaine allows villi to lengthen, resulting in better nutrient absorption. "There's an interaction between the coccidial challenge and betaine in the tissue. Putting more betaine in the diet is positive, he said.

Betaine also prevents dehydration and maintains ionic balance, especially during times of stress such as transport, high heat or pathogen challenges. It is compatible with enzyme function, protects enzymes and membranes from osmotic inactivation and improves water balance, ten Doeschate said.

"Nutrition," he said in conclusion, "can effect changes in intestinal health that may be positive or negative. Of course, it's important to establish a healthy, good functioning gut during the starter period. There are more positive actions we can make in feed design. Use the right enzyme. We can minimize changes during the bird's life. Look at food structure - I'm talking about coarse grinding. And then last, but not least, use some pronutrients," he concluded.

Top producers share first-hand experiences managing coccidiosis with vaccination

Lloyd Maunder Ltd, UK

Tanton: 'Primary disease agents cause a reduction in the birds' immune status.'

At Lloyd Maunder Ltd, a fully integrated, familyrun company that's been producing broilers in England since the 1950s, coccidiosis vaccination has become "fundamental to coccidiosis control," says hatchery manager Mike Tanton.

As a relatively small company, when competition with larger companies in the conventional broiler market became difficult, Lloyd Maunder looked to the high-value, niche market. In 2000, the company started growing organic, free-range broilers and now produces 80,000 of them weekly, which it sells in 15 company shops and to retail outlets, he said.

As part of its new venture, the company developed its own robust breed of bird, the Devonshire Red, which is reared to 4 weeks of age in brood houses with high standards of biosecurity. These high-health birds are then transferred to mobile houses on the range areas. Frequently farms have birds of three different age groups at any one time, presenting tough coccidiosis control challenges, Tanton said.

The sole method of managing coccidiosis in its organic chickens is vaccinating with Paracox-5. Chicks are sprayed at the hatchery when they are one day old. Red food dye included in the vaccine not only encourages preening and ingestion of Paracox-5, it marks the chicks, which lets hatchery staff and farmers receiving the chicks know that birds are protected against coccidiosis. "The application is very easy," Tanton said.

"In round terms we vaccinate with Paracox-5 and the birds don't get coccidiosis. Performance data backs this up with good levels of production performance" he said.

Lloyd Maunder strives to grow birds slowly and keeps weight to about 2.25 kilograms (4.9 pounds) as dictated by market requirements. Slower growth not only helps produce birds that taste good, it also has reduced mortality, Tanton said. In organic systems often the main causes of loss are as a consequence of the more challenging environment the birds grow in and the effects of predation

Amadori Group, Italy

Paracox-5 has helped one of Italy's poultry giants, Amadori Group, launch its "green and healthy" Amadori 10+ product, developed in response to growing consumer demand for drug-free products.

Amadori, a fully integrated company that produces about 110 million broilers annually, found that after gaining experience with Paracox-5, it had "very satisfactory technical results" in its green birds and began using the vaccine in standard broilers too, said Dr. Tonino Toscani, director of health and nutrition for Amadori's poultry business.

In its drug-free birds, use of the vaccine coupled with good management practices enable birds to maintain performance similar to birds receiving traditional in-feed anticoccidials, "which we have demonstrated in many internal trials," Toscani said.

In standard broilers, the vaccine is used primarily to combat rising coccidial resistance to anticoccidial drugs and chemicals. "We hope to ensure greater choice of effective anticoccidial products for the future by rotating the vaccine with medicated feed," he said.

Toscani showed data demonstrating that after three cycles of using the same ionophore anticoccidial, the number of resistant Eimeria coccidia rises. When Paracox-5 is rotated with anticoccidials, ionophore resistance decreases because the vaccine's live, attenuated Eimeria oocysts replace resistant oocysts.

Figure 1. Number of resistant Eimeria strains (red dots) after three cycles of ionophore usage.

Figure 2. Number of resistant Eimeria strains (red dots) after three cycles of Paracox-5 usage.

Isolates of European field coccidia, including some taken from it's own poultry units, have shown that complete coccidial resistance and reduced sensitivity to the in-feed anticoccidials monensin and diclazuril are widespread on farms that strictly use in-feed anticoccidials for coccidiosis control, Toscani added.

In contrast, "our experience suggests that a rotation program that includes at least two or three consecutive vaccinated flocks followed by two or three medicated flocks on the same premises restores sensitivity to standard anticoccidial drugs," he said. In standard flocks, Amadori now usually uses in-feed anticoccidials during winter, which helps reduce the impact of wet litter, and the coccidiosis vaccine in late spring and summer.

No acute disease outbreaks

"Performance results are better than expected," Toscani said, yielding not only good coccidiosis control with no cases of acute disease, but improved feed conversion. He attributes some of Amadori's success with the vaccine to genetic improvement and feed management.

Energy and protein in the diets have been reduced to control enteric problems. In the future, enteric disease in birds vaccinated against coccidiosis may require a dedicated control strategy; medication may be occasionally needed in vaccinated birds as well as in those receiving anticoccidials.

Necrotic enteritis control will also require new strategies in brooding management, diet manipulation and vaccination when it becomes available. Bird density and water quality are other factors that need to be considered, Toscani said.

Note: For more about Amadori's experiences with coccidiosis vaccination, see CocciForum No. 8 or go to www.ThePoultrySite.com/CocciForum.

Martini Alimentare, Italy

Longoni: 'We can't take the risk of residues.'

One of the major Italian poultry producers Martini Alimentare has found that Paracox- 5 significantly simplifies management in flocks that are thinned, a popular practice in Europe. Martini, an integrated company with six feed mills and three slaughterhouses throughout Italy, produces 15 million broilers annually.

Dr. Corrado Longoni, a poultry field veterinarian with Martini, explained that males and females are placed in the same house but are divided by a fence. Females are usually thinned at ages of 35 to 37 days because they have less efficient feed conversion rates. Another thinning might be done for heavy females or light males, usually at 44 to 46 days of age.

After each thinning, practiced in accordance with animal welfare regulations, the fence is moved to give more space to a greater number of faster-growing, large-breasted males that are processed at weights of 3.3 or 3.4 kilograms (7.2 or 7.4 pounds) and, sometimes as high as 4.5 or 4.6 kilograms (9.9 or 10.14 pounds), he said.

Thinning makes it possible to send birds from each group for processing at different ages, depending on market demand. Thinning makes it easier to raise very heavy birds throughout the year, especially during summer months when there is heat stress and higher density could be detrimental. In addition, thinning enables producers to capitalize on economies of scale, since house space is used more efficiently and more kilos of meat per square meter can be produced. All players in the production chain benefit from increased profits, Longoni said.

Medication omplicates thinning

The use of in-feed synthetic or ionophore anticoccidials and their required withdrawal time, which is usually 5 days, seriously complicates thinning, he said. (Figure 1.)

Anticoccidials have to be withdrawn from feed soon enough to ensure that meat has no residues, and puts the flock at risk for a coccidiosis outbreak. Keeping anticoccidials in the feed increases the risk that residues could mistakenly end up in meat at a time when consumer concern about residues is at an all time high. Market flexibility is hindered and feed management becomes a logistical nightmare since two or three withdrawal periods would be needed in thinned flocks, he said.

In addition, "feed mill contamination is a real concern," since Martini makes feed for poultry other than broilers. "We can't take the risk of residues either in feed for non-target species or in our withdrawal feed for broilers," Longoni said.

Vaccinating for coccidiosis eliminates these problems. It protects against coccidiosis, makes it easier and safer to thin flocks and enables Martini to be flexible in response to market needs. Feed management is simplified since no withdrawal diet is needed, and there are no headaches about anticoccidial residues in meat or about cross-contamination, he said. (Figure 2.)

Reduced costs

Paracox-5 has not only improved disease and feed management, it has saved money in several ways, Longoni added. Since it enables thinning to be practiced and house space is used more efficiently, transportation costs for moving day-old chicks and for transporting live birds to slaughterhouses are each down by 20% to 30%.

The cost of transporting feed is reduced by 10% to 20% because there is no need for withdrawal feed or for larger quantities of other feed, although this savings would vary among producers, he said.

Integrators pay farmers based on the kilograms of meat per square meter and flock performance, including the feed conversion ration, the culling rate and meat quality.

"Increased volume per square meter provides farmers with reduced fixed costs and provides integrators with reduced variable costs," Longoni said.

Note: For more about Martini Alimentare's experiences with coccidiosis vaccination, see CocciForum No. 10 or go to www.ThePoultrySite.com/CocciForum.

Figure 1. The required withdrawal of anticoccidials to ensure there are no residues in meat put the thinned flock at risk for a coccidiosis outbreak.

Figure 2. In thinned flocks, Paracox-5 simplifies feed management as well as eliminates concerns about residues in meat.

SADA, Spain

Bellés: 'Complements the practice of thinning flocks'

At Spain's leading poultry producer SADA p.a., a vertically integrated company with nine hatcheries and 10 processing plants, over 3 million chicks are placed with contract farmers weekly.

SADA consumers want poultry meat that is safe to eat from healthy birds raised with the environment and animal welfare in mind, according to integration manager Dr. Santiago Bellés Medall of SADA, a subsidiary of the Netherlands-based Nutreco, one of the world's leading animal nutrition companies.

Potential hazards in food include biological hazards such as bacteria, viruses and parasites, physical hazards such as bones or plastics, and chemical hazards, which include pesticides, antibiotics and anticoccidial residues. Each risk must be identified and separate measures taken to deal with each one. Consequently, SADA has strict procedures in place to ensure that all potential hazards are controlled and prevented, he said.

SADA has found that one way to prevent the risk of anticoccidial residues in poultry meat is by using Paracox-5, which is administered to about 25% of the company's flocks. Use of the vaccine especially complements the practice of thinning flocks, Bellés said.

Thinning, he explained, is practiced on farms with medium and high density "about 14 and 18 birds per square meter (10.76 square feet), respectively "and is based on live weight, not age. About 20% of its birds are grown to about 1.8 kilograms (3.9 pounds) and the rest to more than 2.5 kilograms (5.5 pounds).

When anticoccidials are used, managing withdrawal diets in flocks that each have their own growth rate requires making several different feeds in small quantities. Logistics at the feed mill become complicated, as does the transport of feed and feed management on the farm because several different feeds have to be juggled, increasing the risk for errors or cross-contamination, he said.

It becomes "nearly impossible" to abide by legal requirements intended to prevent anticoccidial residues, Bellés added.

With coccidiosis vaccination, the need for a withdrawal diet is eliminated, which simplifies feed management and, perhaps best of all, enables SADA to guarantee that its poultry is free of residues from ionophore anticoccidials, he said.

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