The Heat is On

Summer is the best time to explore new options for coccidiosis management

Chapman: 'I recommend that producers use an effective chemical drug to help clean up any Eimeria still present in the house.'

Summertime, and the livin' is easy." So goes the song from a Broadway musical. Coincidentally, that line sums up perfectly the seasonal significance of a major poultry protozoan disease.

Summer may be the easiest time to control coccidiosis, but astute management is required to optimize results. That starts with the most basic of chores, spring cleaning, says Dr. H. David Chapman, a parasitologist with the University of Arkansas.

What's next after the annual litter change?

"I recommend that producers use an effective chemical drug to help clean up any Eimeria still present in the house," Chapman says. "Diclazuril is particularly useful because it can be employed any time of year, but don't use it for more than two consecutive flocks."

After diclazuril, vaccinate two or three consecutive flocks with Coccivac- B, he advises. "The vaccine will repopulate the house with drug-sensitive strains and this will help improve subsequent efficacy of ionophores," Chapman explains.

Vaccination Preferable

Seasonal management of coccidiosis varies by company and geographic area. Since producers vary in their warm-weather management schemes, coccidiosis programs involving alternation of a chemical with vaccination should be tailored to those management practices. The overall goal should be to obtain long-term improvements in performance and production. Another goal is to eliminate drug-resistant strains.

"Once the resistant strains are gone, the vaccine will repopulate broiler houses with drug-sensitive forms, and then the use of ionophores can resume," Chapman says.

Since birds are generally released from the brooding area sooner during summer months, they spread oocysts from the initial shedding phase over a wider area. With a decreased concentration of oocysts and a more even spread, reactions and immunity development resulting from the coccidial vaccination will, in turn, be more uniform, adds Dr. Greg Mathis, president of Southern Poultry Research, Inc., Athens, Ga.

"In summer, increased airflow and dry weather reduce litter moisture," Mathis points out. "Dry litter reduces oocyst sporulation, which directly relates to oocyst viability and numbers. With this reduced coccidial pressure, the effects of any errors in a coccidiosis control program, whether anticoccidial or vaccination, will be minimized.

"That makes summer a good time to take advantage of nature's help in this important area of litter management and coccidiosis control," Mathis adds.

Management of Coccivac-B, a live-oocyst vaccine for coccidiosis, is more difficult in winter broiler conditions, adds Dr. Linnea Newman, a consulting veterinarian for S c h e r i n g - P l o u g h A n i m a l Health.

"Besides that, during winter producers can use many anticoccidials with fewer negative reactions," she says. "And if you seed the house with sensitive oocysts via vaccine in summer, winter coccidiostats will work better."

According to Newman, seven of the top 10 U.S. broiler integrators are using a summer vaccination program for coccidiosis in multiple complexes.

"Use of the vaccine in summer goes hand in hand with summer broiler house management," Newman emphasizes. "Summer house conditions are ideal for minimal reactions and excellent performance, without any ionophore-like depression in feed intake during heat stress."

Comfort Zone

Fogging systems are routinely implemented to keep birds cool during summer months, says Dr. Linnea Newman, a consulting veterinarian for Schering-Plough Animal Health. "Fogging is most common for birds four weeks of age and older," she points out.

But frequent fogging wets the litter, and control of litter moisture is an important element of a coccidiosis control program, Newman emphasizes.

"With an ionophore program or if a long withdrawal feed is in use, wet litter conditions during the final weeks before processing will encourage late coccidial challenge and performance loss," Newman warns.

"Proper house management will maximize summer performance," concurs Dr. Charlie Broussard, a technical service veterinarian with the company.

During summer, it's best to keep house air moving at 500 feet per minute, Broussard says, noting that evaporative cooling is becoming an increasingly popular way to keep broiler houses comfortable during summer months. It generally takes eight to 10 fans to properly service a 40' X 500' broiler house.

"Pull up the brood curtain as early as possible in the summer," Broussard advises. "The ideal situation is to implement full-house brooding on day 1. Having more space will reduce competition for feed and water, and it will also reduce the birds' reaction to vaccination."

Source: CocciForum Issue No.3, Schering-Plough Animal Health.
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