No one ever said producing broilers in Sussex County, Delaware, would be easy. Between extremes in the weather and a dense bird population — over 200 million produced annually within 938 square miles, more than any other county in the nation — birds are highly susceptible to disease.

Gumboro disease and runting-stunting syndrome, for instance, are not uncommon in the area. What came as an unexpected development, though, was an outbreak of gangrenous dermatitis at Allen Family Farms in early 2007. And oddly enough, the solution for the costly skin disease was improved intestinal health.

“Dermatitis was affecting from eight to 10 birds per 1,000, and 30 to 40 houses a week were breaking with it. On some of the farms, it was chronic — flock after flock,” reports Gary Gladys, PhD, vice president of live operations for Allen, which is located in Seaford and is the 15th-largest poultry producer in the US.

Although gangrenous dermatitis was unique at Allen Family Farms, it is not a rare occurrence in the poultry industry. The disease has become a major health concern in broiler flocks throughout the US, often resulting in high mortality, carcass condemnations and trimmed parts. Another reason gangrenous dermatitis results in heavy economic losses is because most birds are affected late in their short lives — after 4 weeks of age — at a time they should be experiencing the fastest growth spurt and when feed consumption is highest.

Gangrenous dermatitis has numerous signs, including loss of appetite, gangrenous skin, cellulitis and mortality. One report published in Poultry USA estimated that economic losses from the disease run as high as $1.31 per affected bird.¹

On Allen’s farms, birds with dermatitis were treated with antibiotics and most recovered, despite losses in performance. Some birds died.

Gladys, who joined Allen about 3 years ago, had an idea about how to indirectly manage the onslaught of dermatitis based on past experience at another US poultry company: coccidiosis vaccination.

At the other company, Coccivac-B liveoocyst vaccine was used year-round for organic broilers and was rotated with anticoccidials for a large portion of the antibiotic-free broilers. For whatever reason, “We never would see dermatitis in the birds on Coccivac-B vaccine,” Gladys says.

Although Gladys was eager to implement coccidiosis vaccination at Allen Family Farms, not all of Allen’s broiler grow-out facilities — about 500 independent operations, plus 28 company-owned farms — were ready to buy into the idea, especially since in-feed anticoccidials seemed to be working well.

A few of Allen's farms, however, took the plunge and started vaccinating with Coccivac-B starting in April 2007. As Gladys anticipated, the incidence of dermatitis dropped significantly. In fact, on most of the farms vaccinating, dermatitis disappeared altogether, he says.

Other than switching to a coccidiosis vaccine, no changes were made that could account for the mysterious but welcomed disappearance of dermatitis. Vaccinated birds, for instance, received the same diets as Allen’s other birds, Gladys says.

USE OF VACCINE SOARS

The reduction of dermatitis on Allen farms was so significant that, by the next round of birds, “everyone was jumping on board,” he says. Every week Allen vaccinated about 800,000 broilers with Coccivac-B — close to one-third of the 2.5 million birds that it processes weekly.

“We started out just suggesting use of the vaccine; by the middle of summer, all of Allen’s service reps wanted their flocks on the vaccine,” Gladys says.

Feed conversion in the vaccinated birds has been the same as conventionally raised birds, and by decreasing dermatitis, the high cost of production was improved, he says. In addition, routine posting sessions indicated good coccidiosis control.

Performance with the coccidiosis vaccine was consistent with Gladys’s previous experience at the other poultry company. “There we had antibiotic-free and conventional birds on the same farm but in different houses,” he says. “The performance of coccidiosis-vaccinated birds was the same as conventional birds. Antibiotic-free birds had slightly higher feed conversion, but I don’t think it had anything to do with the coccidiosis vaccine.”

Is coccidiosis vaccination cost-effective? “Yes, certainly more so than feeding salinomycin” if you look at the long-term results, Gladys says. There’s more to consider than the initial cost of vaccination.

Asked why he thinks dermatitis stopped after initiating coccidiosis vaccination, Gladys pauses and then freely admits that he doesn’t know for sure. He’s aware of one theory, however.

Dermatitis is thought to be caused by the bacterium Clostridium perfringens, an opportunistic infection also linked to necrotic enteritis. One supposition is that when in-feed anticoccidials begin to lose their effectiveness — even when it’s not noticeable — “leakage” of coccidiosiscausing Eimeria organisms occurs. That results in coccidiosis breaks and an unhealthy gut, setting the stage for C. perfringens to take over. The detrimental effect of anticoccidial leakage is worse when it occurs late in the growout cycle — after 28 days of age — which is the same time that gangrenous dermatitis usually strikes.

Coccidiosis vaccination stimulates the bird’s natural immune system to provide lifetime coccidiosis control and, by doing so, results in a healthier gut, so C. perfringens can’t get a foothold (see sidebar on page 23). Furthermore, because coccidiosis vaccination is applied at 1 day of age, birds are fully immune to coccidiosis by 4 weeks of age.

Gladys, however, says that before coccidiosis vaccination was implemented, Allen maintained excellent coccidiosis control by rotating in-feed anticoccidials. To keep a close eye on its program, the company turns to technical service representatives from various animal health companies who necropsy six birds from 35 flocks every 8 weeks and score them for lesions. The team includes Intervet/Schering-Plough Animal Health’s parasitologist Dr. Steve Fitz-Coy, who maintains a diagnostic laboratory near the company’s Coccivac-B manufacturing plant in nearby Millsboro, Delaware.

“We’ve been doing this for many years and we rotate anticoccidials based on findings in the posting sessions. We don’t wait until our anticoccidials poop out before we make a change,” Gladys says.

He agrees though that the disappearance of dermatitis after coccidiosis vaccination could simply have occurred because Coccivac-B vaccine contributes to a healthier gut.

Impressed by initial results, all of Allen's farms started using the vaccine this year and will continue to do so until December, when they will switch back to in-feed anticoccidials.

By the end of December, Gladys expects the houses to be “seeded down” with oocysts from Coccivac-B, which are highly sensitive to in-feed anticoccidials, he says. This allows Allen to rotate back to traditional in-feed anticoccidials in the winter months before returning to vaccination in the spring.

BROODING MANAGEMENT CRUCIAL

One important factor contributing to Allen’s newfound enthusiasm for coccidiosis vaccination was a presentation provided by Dr. Matilde Alfonso, technical service veterinarian with Intervet/ Schering-Plough Animal Health, about how coccidiosis vaccination works. “It was a real eye-opener,” Gladys says.

A crucial point Alfonso emphasized was the need to provide the full house to z z coccidiosis-vaccinated birds in half-house brooding by 14 days of age. “It’s one of those things that gets easily overlooked,” he says (see sidebar on pages 25-26).

Despite great results with coccidiosis vaccination and although Gladys says that “I’ve seen coccidiosis vaccination work in organic birds year-round,” Allen plans to keep rotating coccidiosis vaccination with anticoccidials.

Come winter, wind makes it difficult to keep birds warm. In addition, ventilation is less than ideal, and it’s hard to keep litter dry. In birds vaccinated with Coccivac-B, about 25% litter moisture is needed to stimulate the coccidial life cycle, but excessive litter moisture promotes heavy cycling and too much coccidia reaction in birds. These problems make Allen more comfortable using in-feed anticoccidials during cold months.

TRANSITION TO VACCINE EASY

Introducing coccidiosis vaccination in

the spring, however, was a breeze, Gladys says, adding that “it was a really nice transition” for the hatchery.

Day-old chicks are vaccinated with Coccivac-B vaccine via a Spraycox II unit, which has dual nozzles for more uniform distribution. Red dye is included in the vaccine mix to encourage preening and ingestion of the vaccinal oocysts, which stimulate the chicks’ immunity. Halogen lamps are used to further encourage preening and to help dry the birds and prevent them from getting chilled, he says.

Making the switch at the feed mill was not a problem, either. Allen’s feed mill, located in nearby Delmar, Maryland, produces over 28 million pounds of feed (more than 12.7 million kilograms) per week, and a second feed mill is underway in Sussex County to provide feed for 5 million company broilers located within a 10-mile radius of the new mill.

To ensure that coccidiosis-vaccinated birds do not accidentally get feed with anticoccidials, feed for vaccinated chicks is colored red with iron oxide for easy identification.

“Red spots, red feed,” Gladys quips, referring to the red dye sprayed on birds with vaccination at the hatchery and the colored feed.

Initiating coccidiosis vaccine requires preplanning, Gladys says, but “it just comes down to whether you want something to work or not.”

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