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COCCI FAQs

Schering-Plough’s tech service team answers questions about managing coccidiosis in broilers.

Q. AFTER USING COCCIVAC-B OR PARACOX-5 ONE OR TWO TIMES, ARE THERE ENOUGH OOCYSTS IN THE LITTER TO STIMULATE NATURAL IMMUNITY WITHOUT VACCINATION OR WITH A REDUCED DOSE?

A. No. While it’s true that oocysts are in the litter, reliable immunity will only be achieved by giving each bird a controlled, balanced dose of Eimeria organisms through vaccination to all new flocks.

Q.WHAT IS THE EFFECT OF IN-FEED ANTICOCCIDIALS ON BIRDS THAT HAVE BEEN VACCINATED AGAINST COCCIDIOSIS?

A. If in-feed anticoccidials are used before Eimeria organisms become established, the number of oocysts replicating in birds can be reduced significantly. The result will be less than optimal immunity against coccidiosis.

Q.IF CHICKENS COME FROM TWO SOURCES AND SOME ARE VACCINATED AND SOME ARE NOT, WHAT DO YOU DO?

A. Go back and revaccinate. An alternative would be to vaccinate just the birds that had not been vaccinated earlier, even if this requires segregating and confining those birds for a day or two in a small area. Then they could be mixed with the rest of the bird population that was already vaccinated.

Q. IS VACCINATION WITH COCCIVAC-B OR PARACOX-5 EFFECTIVE ON FARMS THAT ALREADY HAVE COCCIDIOSIS OR WHEN THERE ARE HIGH LEVELS OF OOCYSTS IN THE LITTER?

A. Yes. If birds are vaccinated on day 1, the organisms established during the first week of life tend to take up residence. These infections do not prevent or eliminate wild oocysts in the environment that affect chickens, but oocysts from the vaccine tend to dominate early infections. Thus, the impact of wild oocysts isn’t as severe. Giving birds the initial exposure is very critical because the subsequent exposure will be less severe. If nonvaccinated birds are, say, 10 days old, and they’re just getting their initial exposure to wild coccidia through ingestion of organisms, the amount they get is uncontrolled. With vaccination, that first exposure is controlled. That’s why we advise hatchery vaccination on the first day for Coccivac-B and Paracox-5, because it allows birds in your system to start responding to the antigen.

Q. DOES THE TYPE OF LITTER MATERIAL INFLUENCE VACCINATION WITH COCCIVAC-B OR PARACOX-5?

A. The quantity probably has more impact than the type of material. We’ve seen coccidia in all types of litter. The thicker the depth of the litter, the more diluted will be the fecal matter, and the reverse is also true. It is best to have a thick, rather than thin, layer of litter. Litter material should be high capacity to absorb humidity.

Q.IF YOU ARE USING COCCIVAC-B OR PARACOX-5 AND WANT TO SWITCH TO ANTICOCCIDIALS, WHAT KIND OF ANTICOCCIDIAL PROGRAM IS NECESSARY?

A. Based on our experience, any of the anticoccidials should work if you use the vaccine long enough, because the organisms from the vaccines are sensitive to several anticoccidial drugs.

Q. IS THERE A BEST TIME OF YEAR TO USE COCCIVAC-B OR PARACOX-5?

A. The vaccines can be used at any time of year. There is a producer in the Southeast United States and several companies in Europe that have been using the vaccine year-round for several years with excellent success. The key is proper management of factors such as bird density and litter moisture.

Q.WHAT ARE THE PROS AND CONS OF THE MAJOR IN-FEED ANTICOCCIDIALS FOR SHORT- AND LONG-TERM COCCIDIOSIS CONTROL?

A. Chemical or synthetic anticoccidials are highly effective when they’re first used. Unfortunately, Eimeria organisms can develop resistance to them fairly quickly, so you can use them only for one or two cycles. Resistance is also a problem with ionophore antibiotics, but it appears to happen more quietly and gradually. In some ways, however, that can be more costly than a total product failure because the production losses are not as apparent, even though they may still be significant. Rotating ionophore antibiotics can help slow this resistance, but the impact may be minimal because the ionophores are all similar compounds and there is cross-resistance among them; that is, strains of coccidia that become resistant to one ionophore drug may become resistant to others as well. Vaccinating for coccidiosis for three or four cycles can help break up the cycle of resistance and restore sensitivity to in-feed anticoccidials.

Q. WHY DON’T I SEE ANY CLINICAL SIGNS OR IMPAIRED PERFORMANCE AS A RESULT OF LEAKAGE AND RESISTANCE IN AN IONOPHORE PROGRAM?

A. You are seeing impaired performance, it’s just not being quantified. Impaired performance due to leakage — when some Eimeria oocysts survive initial treatment and then begin to multiply and reinfect birds — is not always revealed by the benchmarking methods used by some poultry companies. If impaired performance is related to E. maxima late in the grow-out, there may be no clinical signs, but there will be microscopic evidence of subclinical coccidiosis. Unfortunately, many producers don’t see the shortfall in performance until they switch treatment methods and experience a performance gain. Poor performance due to leakage and resistance often improves with vaccination, which initiates early coccidial cycling, helps build immunity and lowers the oocyst carryover load in subsequent flocks.

Q. WILL SHUTTLING IN-FEED ANTICOCCIDIALS — FOR EXAMPLE, USING A CHEMICAL IN THE STARTER PHASE AND AN IONOPHORE ANTIBIOTIC IN THE GROWER PHASE — REDUCE RESISTANCE TO IN-FEED ANTICOCCIDIALS BETTER THAN SIMPLY ROTATING PRODUCTS WITH EACH FLOCK?

A. No. The more often you put an infeed anticoccidial product in front of Eimeria organisms, the more potential there is for resistance to develop. The unfortunate part of a shuttle program is that you can develop resistance to anticoccidials.

Q. AFTER REPEATED USE OF COCCIVAC-B OR PARACOX-5, CAN I START VACCINATING WITH A HALF-DOSE SINCE THE POULTRY HOUSE IS NOW SEEDED WITH OOCYSTS FROM THE VACCINE?

A. Definitely not. It is critically important to use a full, controlled dose to ensure uniform distribution. Halfdosing increases the risk that some birds won’t get enough of the vaccine and some may not get any. Unvaccinated or inadequately vaccinated birds will not experience oocyst cycling or develop immunity at the same time as vaccinated birds, and they can develop significant reactions upon exposure to coccidia. In addition, there is a balance between different Eimeria species; a certain number of one species — say E. acervulina — helps reduce the multiplication of another species — say E. maxima. If a half-dose is administered, this balance can be disrupted and uneven multiplication of Eimeria parasites may occur.

Q. WHY AREN’T MORE COMPANIES USING COCCIVAC-B OR PARACOX-5 IF IT’S SO GOOD?

A. Vaccinating for coccidiosis represents a big change in the way that poultry companies have controlled coccidiosis. Coccivac-B and Paracox-5 have been shown to be effective and safe products. In fact, industry data show that when live performance is measured, the vaccine is comparable, if not better, than standard in-feed anticoccidial programs However, it’s difficult to convince people to try something new; that’s the reason more companies haven’t yet switched to Coccivac-B or Paracox-5. So far, many innovative companies have successfully adopted Coccivac-B or Paracox-5 as part of the their long term anticoccidial strategy. As more companies recognize the losses associated with ionophore oocyst “leakage,” they will likely adopt vaccination.



Source: CocciForum Issue No.11, Schering-Plough Animal Health.

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