New-generation coccidiosis vaccine for layers approved by USDA

Coccivac-D2, a new-generation coccidiosis vaccine for chickens, has been approved by USDA and will replace Coccivac-D.

“The new vaccine is very similar to Coccivac-D, but its spectrum is even more in step with the Eimeria populations found in today’s layer operations,” says Dr. Charlie Broussard, director of US poultry technical services for Merck Animal Health, developer of Coccivac vaccines.

Coccivac-D2 has a more focused antigen profile of the six major pathogenic species of chicken coccidia (E. tenella, E. mivati, E. acervulina, E. maxima, E. brunetti and E. necatrix). “We eliminated E. hagani and E. praecox, two of the least important pathogenic Eimeria species of the chicken,” the veterinarian says.

All master seeds used to produce the vaccinal oocysts in Coccivac-D2 were tested for purity and quality and were re-qualified by USDA, he notes.

As with all Coccivac vaccines, Coccivac-D2 provides a balanced, controlled dose of live Eimeria oocysts to stimulate the bird’s natural immunity against coccidiosis, Broussard says, but he stresses that proper management after vaccination is imperative.

LEADING PROBLEM IN CAGED PULLETS

Broussard points to a survey indicating that coccidiosis is a leading health problem in caged pullets; the survey, conducted by the Association of Veterinarians in Egg Production, also indicated that coccidiosis is a leading health problem in cage-free pullets and cage-free layers (Layer Health, Issue 5, page 3).

In caged pullets, coccidiosis is thought to be a problem due to contamination of houses with coccidial oocysts from past outbreaks and delivery of coccidial oocysts to caged chickens by flies or beetles.

When vaccinating day-old chicks with Coccivac-D2, Broussard advises hatcheries to use the newer, spray-on equipment.

“After vaccine application and bird placement, you need to make sure that the vaccine oocysts are recycling, because it’s repeated exposure that results in full immunity against coccidiosis. Bird density and litter moisture need to be adequate for recycling, but you don’t want to overdo it either,” he says.

PLACE BIRDS CAREFULLY

The results of a study conducted by Merck Animal Health indicate that pullets started in lower-tiered cages should be transferred to lower-tiered cages, where the coccidial challenge is greatest because after birds grow a bit, they can reach the “clean” returning manure belt. Conversely, pullets that start out in higher-tiered cages should be transferred to higher-tiered cages, where the coccidial challenge is minimal.

Ensuring the development of immunity in caged pullets is somewhat more difficult compared to broilers, Broussard acknowledges, because the birds don’t have as much exposure to feces and litter, but with the right management, “birds can achieve really solid immunity after coccidiosis vaccination.”

Coccivac-D2 is currently available in 5,000- and 1,000-dose vials.