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Dr. Marshall Putnam

A new coccidiosis-control strategy that incorporates vaccination has improved disease control and yielded additional, unexpected benefits for a major US producer.

Wayne Farms used to depend on an ionophore-leakage program and the buildup of coccidial oocysts in the litter to initiate immunity in its broilers, according to Dr. Marshall Putnam, director of health for the Georgia-based company — the fifth largest poultry producer in the US, processing roughly 5.6 million birds weekly from eight live-production complexes.

“We used to typically run starter feed up to about 18 days of age and the maximum ionophore level, trying to get birds off to a good start,” he explained. “Then we’d switch to a grower feed and a lower level of ionophores to promote leakage at around 19 days of age, and we’d run that up to around 40 days of age.”

Wayne, which primarily produces large birds, was “very set on trying to get immunity developed in these birds,” the veterinarian added, noting that the company used a withdrawal feed after 40 days.

Everything seemed right with the coccidiosis-control program until 2000, when Wayne started using diclazuril, a chemical anticoccidial that was new to the US poultry industry. “We immediately picked up 4 to 6 points in feed conversion [at some of the complexes], and that got everybody’s attention because it was a significant improvement in cost for us,” Putnam said.

Ultimately, resistance to diclazuril developed and the results weren’t as good, but the experience demonstrated that Wayne Farms had been losing performance with its ionophore program, prompting the company to scrutinize its coccidiosis-control program. It took a look at Coccivac-B, the live coccidial-oocyst vaccine developed by Intervet/Schering-Plough Animal Health.

Successful in small-bird complex

“As it stands now, all of our complexes have used the vaccine,” Putnam said. Some still rotate the vaccine with ionophores, but four used the vaccine all year in 2009 and even a small-bird complex was “very successful” using the vaccine over winter.

He cautioned that initiating use of a coccidiosis vaccine requires educating farm managers carefully. “They get real nervous because they are held accountable for performance at their complexes,” Putnam said. “They don’t expect the vaccine to work as well as an anticoccidial because they’ve had it drilled into their heads that we don’t want any coccidia. Well, Mother Nature’s going to find a way — the birds are going to get coccidia at some point in their lives; what we’re trying to do with the vaccine is dictate when they get it.”

Putnam also warned that flocks coming off anticoccidials early are going to have late coccidial-oocyst leakage. “Then, when you put a vaccine in, you’re going to have some problems with your first vaccine cycle,” he added. “There could be a necrotic enteritis outbreak. Performance is going to go up and down, but it’s going to get better.”

By the second vaccine cycle and beyond, performance continues to improve as the oocyst load in the house stabilizes, he said, noting that Wayne Farms still uses built-up litter.

Putnam added that changes in performance tend to be blamed on the coccidiosis-control method — particularly if it’s a vaccine — when, in fact, the real problem could be house management during hot weather. For that reason, Wayne Farms has tried to schedule vaccine use so that the first cycle of vaccinated birds is sold at a time that does not coincide with stressful weather, Putnam said.

Wayne Farms has also used in-feed antibiotics during the first cycle of Coccivac-B after ionophore use, to support gut health during the transition, he noted.

The company has determined that coccidiosis vaccination is effective based on results at posting sessions and on broiler performance. Posting sessions reflect how birds are cycling coccidia and correlates with performance, he said.

With the old ionophore program — when the maximum possible amount was used, then dropped down to a lower level in the grower feed to save on costs and promote immunity — “we couldn’t save enough to make up for lost performance,” Putnam said.

Immune system status important

He emphasized the importance of broiler immune status. “I think a lot of people in the US overlook the immune system status of their flocks, but it’s critical and it’s the foundation for any [effective] coccidiosis-control program,” Putnam said. House management is likewise important, since bird stress can “blow the immune system out of birds.”

Putnam said he tracks coccidial-cycling patterns closely. At posting sessions, “I tell my folks that I don’t really care what they’re seeing at 15, 16 or even 22 days of age...I get nervous if there’s cycling at 35 or 38 days of age and +1 or +2 lesions,” since research has shown that even minor coccidial lesions have a negative impact on bird performance.

After several years of experience with coccidiosis vaccination and rotating the vaccine with an in-feed anticoccidial program, Putnam said he no longer wants to see a bump up in performance after the switch to a vaccine. When ionophores are used, a lower level is provided in the starter feed, and a higher level is provided in the grower feed — the opposite of what the company used to do. “I want those birds to get leakage in their first 2 or 3 weeks of life,” he said. “Then I’m going to put the maximum level on them during the growing phase.”

As a result, the transition from ionophores to the vaccine is smooth, and “we’ve seen absolutely no change in performance from one week to the next” because the oocyst load in the house isn’t as great for vaccinated birds, he said.

Use of the vaccine restored the efficacy of ionophores, and “we’re not seeing any issues with drug resistance,” Putnam said.

An unexpected benefit was the elimination of gangrenous dermatitis. This condition, caused by a subacute clostridial infection, was resulting in mortality. But “when we went to the vaccine, the problem stopped,” he said.

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