Coccidiosis, an enteric disease caused by Eimeria species, continues to be a substantial economic burden on the global poultry industry. With increased concerns regarding prophylactic antimicrobials to control coccidiosis alternate methods of preventative control have been developed, yet innovation to strengthen these methods has been limited, according to K.R. Price of the University of Guelph in Canada and co-authors there and with Merck Animal Health and the University of Arkansas Poultry Science Department in the US.

In a paper in International Journal of Poultry Science, they explain that live Eimeria vaccination stimulates immunity from the first small dose of vaccinal oocysts and is enhanced through low-dose faecal-oral transmission ('cycling') of these oocysts. This immune response manifests as no pathogenic effects with minimal parasite reproduction.

The success of a live coccidiosis vaccine is inextricably linked to poultry management techniques that successfully balance oocyst cycling with modest numbers of infective oocysts.

The breadth of cage floor coverage using a durable fibre tray (lasting around five weeks) to improve oocyst cycling in live vaccinated caged pullets was investigated.

Pullets were inoculated via oral gavage with mixed vaccinal Eimeria species and reared under simulated commercial conditions with 0, 20, 40 or 60 per cent tray coverage from hatch to 42 days of age, then subsequently challenged with homologous Eimeria species.

Plumage cleanliness, foot pad dermatitis (FPD), wire floor FPD and hock burn were also assessed in the trial.

Mean total oocyst shed (output) between birds housed with or without coverage differed significantly after challenge infection. Pullets on 40 per cent coverage had significantly lower mean oocyst output than the other treatment groups (>99 per cent compared to no coverage). No difference in mean total oocyst output was found between the 20 and 60 per cent treatment groups.

Lesion scores mirrored oocyst shed results, according to Price and co-authors. Increased access to oocysts using 40 per cent cage floor coverage with fibre trays over five weeks allowed for improved vaccine success in live coccidiosis vaccinated caged pullets.

In their paper, the researchers concluded: "We demonstrated that 40 per cent cent coverage of cage floors with durable fibre trays for an extended duration (around five weeks) had a significant and beneficial impact on the success of live coccidiosis vaccination with cage-reared pullets. Birds housed with 40 per cent coverage of their cage floors developed the strongest protective immunity against challenge.

"Animal welfare scores post-treatment were modest suggesting that the direct impact on the birds of the cage flooring modification was clinically irrelevant.

"This 'easy-to-use', relatively inexpensive and environmentally friendly modification requires no additional labour after the day of pullet placement because the fibre trays disintegrate and fall through the wire floor into the manure disposal system after approximately five weeks.

"Adoption of this environmental management tool may enhance the success of live vaccination against coccidiosis in cage-reared poultry," added Price and co-authors.

Reference

^{Price K.R., M.T. Guerin, L. Newman, B.M. Hargis and J.R. Barta. 2013. Examination of a novel practical poultry management method to enhance the effect of live Eimeria vaccination for conventionally housed replacement layer pullets. Intern. J. Poult. Sci. 12 (3):175-184.}

May 2013