One of the keys to a successful coccidiosis vaccination program is the recycling process after the first cycle of the Eimeria parasites. Five to seven days post-vaccination, chicks will begin excreting vaccine strain oocysts in their feces, re-exposing the flock, further stimulating the chicks’ immune response again, and further increasing their level of immunity. Depending on the strain, two to three cycles of re-ingestion is necessary to achieve the best possible immunity. 

To optimize the recycling process, hatchery and on-farm personnel must be committed to their responsibilities for preventing coccidiosis.

Hatchery Personnel

On-farm Personnel

  • Use a live, infective vaccine
  • Ensure a uniform vaccine application and vaccine uptake
  • Create a suitable environment for sporulation of excreted oocysts to take place 
  • Create a suitable environment for uniform contact between the sporulated oocysts and the vaccinated chicks for re-ingestion to take place.
For more information see SOPs under Relevant Links

To achieve a suitable environment for sporulation and uniform contact, it’s critical to manage the stocking density of the flock. Measuring litter moisture is an easy way to determine whether the environment is suitable for sporulation. It can also be easily adjusted by adapting the stocking density to either increase litter moisture or reduce it. 

Recycling Process for the Eimeria Vaccine

During the recycling process , farm personnel also need to be aware of a number of other factors that need to be considered for birds to achieve the best possible immunity:

  • Avoid anticoccidials
  • Avoid antibiotics (Sulpha's/Tetracyclines, etc)
  • Ensure adequate feeder and drinker space
  • Limit possible stressors (ventilation, temperature, handling, etc.) 
  • Mycotoxins in the feed
  • Immuno-suppressive diseases (Marek's Disease, Infectious Bursal Disease, and Chicken Infectious Anemia) 

Monitoring the development of the immunity can be done by measuring the number of oocysts shed per gram of feces during critical stages of oocyst shedding in the first 4 weeks post-vaccination. Oocysts per grams (OPG) is done on fecal samples taken on Day 7/14/21/28 post vaccination.

  • Chickens - Day 7/14/21/28 Post-vaccination  
  • Turkeys - Day 6/13/20/27 Post-vaccination

Do not skip sampling days 

  • The first count should be positive. This is a very good indicator of the effectiveness of the vaccine application done in the hatchery as well as an indicator that the vaccine that was used was still infective.
  • The second count should show significant increase. This is used as an indicator that the shed oocysts sporulated and re-ingestion of these shed oocsyts have taken place.
  • Oocyst shedding usually peaks at the time of the third count. This is also the time when some mild reaction can be observed in the chickens or turkeys.
  • The fourth count shows a dramatic drop from the third count. This is when the immunity has developed sufficiently to effectively prevent massive infection. 

Performing oocyst counts are a valuable tool in understanding the cycling of the vaccine on the farm. Interpretation can sometimes be difficult, but the longer this is done, providing historical data to compare against, the easier and more meaningful it is to interpret. 

SOPs from sample taking and performing OPG counts can be found under Relevant Links.