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COCCI Confidential

Vaccine Controls Coccidiosis, Improves Performance In Integrator's Controlled Study

Editor’s note: The information for this article was provided by a major US poultry company on the condition that its name and location be kept confidential. The sources mentioned in the article have nevertheless reviewed the information for technical accuracy and approved it for publication in CocciForum. It is presented here in our newest feature, Cocci Confidential, to help the poultry industry learn from these real-world experiences and improve their management of coccidiosis. If you have a story you would like to share with Cocci Confidential, please contact the editor at JFeeks@prworks.net or call 508-627-6949 (US).

The veterinarian was still skeptical. He wanted proof that vaccinating broilers to prevent coccidiosis wouldn’t hurt performance.

His employer, a major poultry integrator in the US processing millions of birds annually, hadn’t been vaccinating against coccidiosis for long. Initially, there were some performance irregularities, but he couldn’t ignore the numbers from the third cycle — the results were stellar.

A good study was needed, but comparing a coccidiosis vaccine directly to a feed-grade anticoccidial program under true field conditions would be difficult. Non-medicated feed would have to be provided to houses with vaccinated flocks; in particular, no anticoccidials could be fed to vaccinated birds — they could destroy the vaccine oocysts that help build immunity to coccidiosis.

Anticoccidial feed would have to be delivered to other houses on the same farms with unvaccinated birds. Care would have to be taken to avoid manufacturing or delivery errors for the life of the flock. It would be a challenge for a big and busy integrator, but data was needed to determine whether changes should be made to the standard coccidiosis control program.

Study design

In the fall of 2002, a multi-farm, pairedhouse trial was initiated. It involved four, 4-house farms raising heavy broilers (7.5 lbs). The integrator vaccinated two houses on each farm with Coccivac-B, a live-oocyst vaccine; in the remaining houses, birds were fed an anticoccidial shuttle utilizing narasin and nicarbazin, which was the integrator’s standard program and served as the study’s control. Evaluations were conducted on 156,000 birds from the vaccinated group and on 156,000 birds from the control group.

The ration formulation for the two treatments was consistent except that vaccinated birds received a virginiamycin premix in the starter and finisher ration and bacitracin methylene disalicylate and roxarsone in the grower ration, while controls received narasin, nicarbazin and bacitracin methylene disalicylate in the starter ration and narasin and roxarsone in the grower and finisher rations (Table 1).

Findings

At 4 weeks (28 days) and 7.5 weeks of age (52 days), veterinarians from Schering-Plough Animal Health and Alpharma Inc. conducted posting sessions on the 16 test houses, where they looked for evidence of coccidialspecies. They used microscopic evaluation for Eimeria maxima, since this species does not always produce distinct gross lesions and is more likely than other Eimeria species to impair feed conversion and weight gain. By 51 to 55 days of age, most of the lesions received mild scores of +1 and +2 (Figures 1 and 2).

In addition, the integrator processed birds from each treatment separately. The processing plant reported standard performance parameters such as the percent livability, gross pounds sold, average weight, feed conversion and average daily gain (Table 2).

The results

Vaccinated birds and the controls receiving feed-grade anticoccidials each demonstrated mild coccidial lesions at 4 weeks of age. However, the lesions had resolved by the second post-mortem exam at 7.5 weeks of age (Figures 1 and 2). Vaccination did not appear to affect either 7-day mortality or overall livability compared to controls.

On a farm-by-farm basis, vaccinated flocks outperformed or equaled the performance of the control flocks for all significant parameters. Vaccinated flocks also demonstrated better performance on an averaged basis. Compared to flocks receiving standard ionophores, those that were vaccinated had:

• An average weight 9.6 points higher

• An average feed conversion 1.6 points lower

• A caloric conversion 11 calories lower

• An adjusted caloric conversion 33 calories lower

• A standard cost per pound 0.17 cents lower

Discussion & conclusion

Coccivac delivers a controlled, balanced dose of sporulated or infective oocysts of the economically significant Eimeria species. A new generation of oocysts develop in vaccinated birds and are then excreted, providing reexposure to Eimeria oocysts. The process stimulates natural, long-lasting immunity.

Generally, it takes about two to three oocyst cycles for strong immunity to develop. Vaccinated birds may be presented with a field challenge from previous flocks before their immunity is fully established, which explains why performance results may seem irregular with the first cycle of Coccivac-B.

In this rare multi-farm, paired-house study, Coccivac-B was successfully used for the long-term management of coccidiosis without sacrificing performance. In other words, Coccivac-B used in real-world conditions not only controlled coccidiosis, it improved broiler performance compared to ionophore anticoccidials.

Source: CocciForum Issue No.7, Schering-Plough Animal Health.

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