Cover Story - Tying the Score

Performance of vaccinated birds equals or exceeds birds receiving traditional in-feed coccidiostats

Recent studies with roasters and broilers finished in as little as 42 days indicate that performance of poultry immunized with a coccidiosis vaccine is just as good as in birds that continuously receive an in-feed coccidiostat.

"We're finding that with live oocyst vaccination, we're coming closer to the same kind of productivity you'd find in the field with use of in-feed anticoccidials," says Dr. Harry Danforth, parasitologist with the USDA's Agricultural Research Center, Beltsville, Md.

In a study conducted by Dr. Danforth, weight gain and feed efficiency in roasters that received a live oocyst vaccination initially lagged behind those fed an anticoccidial. This was expected because birds are exposed to oocysts, or coccidia organisms, in the vaccine that ultimately enable the birds to develop immunity against coccidiosis.

Performance in vaccinated birds, however, caught up to that of the infeed group. By the end of the study, there was no statistically significant difference in weight or feed efficiency between the two groups of birds, which were grown 56 to 63 days, Dr. Danforth says.

The results showed not only that vaccination with live oocysts elicited "significant protection" against coccidiosis, but that it resulted in "average bird weight gains and feed efficiency similar to that obtained with conventional anticoccidial medications," Dr. Danforth concludes (Int J Parasitol 1998 Jul; 28 (7):1099-109).

Results Similar in Broilers

The results were similar in broiler studies conducted by researcher Dr. Greg.Mathis of Southern Poultry Research, Inc., Athens, Ga.

In Dr. Mathis' study, presented last year at the American Association of Avian Pathologists conference, some birds received the live oocyst vaccine at hatching and other, nonvaccinated birds were fed the anticoccidial salinomycin in starter and grower feeds. The broilers were housed in a floor pen facility and managed as they would be in a commercial operation.

At day 14, average feed conversion and live weights were similar in the vaccine and salinomycin groups. By Day 21, an effect on performance due to coccidiosis vaccination occurred and the vaccinated group trailed behind the nonvaccinated group in weight and feed conversion.

However, by day 28, performance in the birds receiving the anticoccidial had declined and there was no significant difference in weight gain or feed conversation between the vaccinated and in-feed groups. Performance in both groups remained the same for the remainder of the study, Dr. Mathis says.

Field Data Confirm Results

Field data provided by Schering Plough Animal Health, the company that manufactures Coccivac®-B, a live oocyst vaccine, confirmed the results of Dr. Mathis' floor pen studies.

Commercial flocks raised in high temperatures during summer received either the vaccine or an in-feed anticoccidial.

"The weights from the two programs were identical. In fact, in the field trials, weight and feed conversion among vaccinated birds were sometimes better than those of broilers receiving salinomycin," Dr. Mathis says.

The field studies included 5- and 6- pound broilers and demonstrated that vaccination can be used for smaller broilers grown to 42 days, as well as those grown to 49 days of age.
Previous studies have shown that vaccinating birds against coccidiosis causes some intestinal disruption and resulting performance loss. However, Dr. Mathis says his research shows that the impact on performance is only temporary.

He originally thought that the benefits of vaccination would not outweigh any negative impact on performance, but the trend today is for a longer grow-out period and further processed birds. In this case, the benefits of immunity can equal or exceed any loss in performance, "especially when you take into consideration the cost of anticoccidial medications."

Benefits of Vaccination

The major advantage of using a coccidiosis vaccine is improved coccidiosis control, Dr. Danforth says. Rotating the vaccine with coccidiostats helps combat resistance to the in-feed products, which is a well-recognized problem in the poultry industry.

"I'd recommend the vaccine to poultry producers where drug resistance is a problem with coccidiosis, but it depends on where you go," he says.

"In some areas, in-feed coccidiostats still work well. In other areas of the U.S., immunization would be a real plus because you aren't getting as good a result with in-feed anticoccidials."

Spray Cabinet Technology Simplifies Coccidiosis Vaccination in Poultry

Spray cabinet technology makes it easier to administer the live oocyst coccidiosis vaccine and helps assure even distribution, say poultry experts.

"With the spray cabinet, you put 100 chickens in a box and mist them with the vaccine solution," says Dr. Phil Hargis, an independent poultry nutritionist based in Batesville, Ark. " It's a lot more likely that the vast majority of chicks will get the vaccine than if workers spray it on feed pans or if the vaccine is administered in water."

Dr. Larry McDougald, parasitologist at the University of Georgia, Athens, says, "We don't have the final say yet on which is the best method of distributing this vaccine, but the newer methods, such as the spray cabinet, are greatly improved over older methods. With water administration, the vaccine isn't distributed properly and exposure is uneven."

Dr. Harry Danforth adds, "The spray cabinet is more likely to be accepted because poultry producers already have spray cabinet technology to treat for other diseases, such as bronchitis." Other methods can be problematic. Eye administration, for instance, requires individual birds to be handled, which isn't as efficient, he says.

"Better methods of administration may come along, but right now, the spray cabinet is one of the best. It's simpler, quicker and takes less people and time to do it," Dr. Danforth says.

Dr. John McCarty, a poultry veterinarian with Schering-Plough Animal Health, explains that sprayed chicks preen and ingest the vaccine orally, which helps obtain more uniform administration throughout a flock.

Source: CocciForum Issue No.1, Schering-Plough Animal Health.

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