Coccidiosis control continues to be a top concern for broiler veterinarians in the U.S., in spite of the estimated $90 million per year spent on prevention, according to Dr. Greg Mathis, president and researcher, Southern Poultry Research, Inc. Mathis, speaking at WATT Global Media's "Coccidiosis vaccination: A new approach to Salmonella control" webinar, said that broilers vaccinated for coccidiosis have lower lesion scores than do birds treated with either chemical coccidiostats or ionophores.
Mathis said that there are nine species of coccidia that impact broilers, with E. acervulina, E. tenella and E. maxima being the most prevalent. E. tenella is primarily found in the ceca and it is the species of coccidia that seems to affect Salmonella levels in broilers the most. Mathis said that better control of E. tenella may lower Salmonella incidence in a flock at time of market.
Impact of vaccination
Dr. Charles Hofacre, researcher, poultry diagnostic research center, University of Georgia, said that coccidiosis vaccination is regaining popularity with broiler companies for a number of factors. Resistance of coccidia populations in broiler houses to both chemical coccidiostats and ionophores continues to be a growing problem with no new drugs introduced in the last few decades. Hofacre said that vaccinating for coccidiosis reestablishes populations of susceptible strains of coccidia on broiler farms. Finally, he said that the growth of the antibiotic-free movement among some consumers has also increased use of coccidiosis vaccines.
Research has shown that coccidiosis breaks in broilers associated with E. necatrix and E. tenella are associated with increases in Salmonella colonization in the bird. Hofacre said the E. necatrix control in breeders plays a role in helping to keeps Salmonella loads on chicks low, but that E. tenella control is of more importance for controlling Salmonella colonization in the broiler house.
Coccidiosis control and Salmonella
Hofacre reported on a challenge study where birds were raised on built up litter and where either vaccinated for coccidiosis or treated with an ionophore coccidiostat, Salinomycin. In addition to being raised on built-up litter, half of the birds in this study were challenged with Salmonella Heidelberg. Salmonella Heidelberg levels were numerically lower in the drag swabs of the pens with vaccinated birds. The vaccinated broilers had lower cecal Salmonella counts than did the Salinomycin treated birds.
"Coccidia vaccine in this study numerically reduced environmental load, prevalence and cecal number of Salmonella Heidelberg," said Hofacre. Coccidiosis control alone won't solve Salmonella problems for a broiler producer, but it can contribute to the solution. "We reduce Salmonella not by silver bullets but by multiple methods that build to success."