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Broilers Reared on Litter - Live Vaccines
This information is NOT a housing management guide. These sections were created to help explain the relationship between housing and oocyst ingestion. Please consult your veterinarian and bird management guide from the breeding company for housing management information.

Brooding

The brooding and immediate post-brooding periods are important to vaccine success because this is the time where offspring vaccine oocysts can cycle in the barn at low levels. Essentially, the cycling during this phase is acting as an immunity booster to the original vaccine dose; without this cycling, the vaccine will not work as effectively.

General Good Barn Practice Provide chicks with clean, biosecure housing. Ensure that feed and water are readily available to the chicks when they are placed (1). Additionally, proper heat, ventilation and lighting as well as feed and water quality are required for good rearing management (1).

Half House Brooding - This management method is a modification of whole house brooding. The birds are confined to half of the house with a set of drinker and feeder lines. The house is heated with forced air heaters and the aim is to achieve uniform temperature in the air space. In this management method, bird density is increased for the period they are in half of the house. A typical Eimeria species will start to shed from the bird between 5 and 7 days post initial ingestion of an infective oocyst (i.e. live vaccine administration). The oocyst takes between 24-48 hours to become infective once shed. If birds are kept in the half house for at least 10 days (and if relative humidity, temperature and oxygen access are maintained), this brooding method may provide sufficient duration for low level cycling and thus sufficient exposure to infective oocysts.

Note: If birds are moved to the whole barn earlier than 10 days there will have been oocyst shedding, oocyst sporulation but not enough time to allow for the ingestion of these shed oocysts as is needed for the live vaccine to work effectively.

chickenhalfhouse

Figure 1. Simple diagram illustrating Eimeria oocyst build-up in a half house brooding system.  In this brooding method bird density is increased for the period the broilers are in half of the house.  As offspring vaccine oocysts are shed into the environment they can accumulate in the occupied area of the house.  If the birds are kept in half of the house until the offspring oocysts sporulate and become infective, this brooding method may provide the sufficient duration and exposure to oocysts for low-level cycling.

Examplehalfhousebrooding

Figure 2. An example of half house brooding (Picture Credit: Guy Kostrey, Sceneskape Productions).

Physical Environment During Brooding - According to management guidelines (1) providing 60% paper coverage below the feeder and water lines during the brood phase would provide the extra feed and water spillage needed to stimulate bird activity and appetite as early as possible. Interestingly, this method may provide the needed coverage to allow progeny vaccine oocysts to remain at the litter surface for ingestion by the bird (low-level oocyst cycling). Without this coverage, oocysts may fall between the litter material used thus preventing birds from ingesting them. If the removal of the paper is a normal practice, it has to be removed before 5 days after vaccination, or only after 10 days after vaccination. Warning: If you remove the paper between 5 and 10 days after vaccination during the peak vaccine oocyst shed time you will remove the shed oocysts from the barn. Removing these oocysts from the barn may impact vaccine success. 

Physical Environment During Brooding - Chicks during the brood stage are small enough that they may be able to fit in the open feeders. Be aware that these chicks are able to defecate into the feeders and this is another spot where birds can ingest infectious oocysts if present in the feces. Additionally, nipple cups attached to drinkers are also potential reservoirs for oocysts.

Birdonlitterinfeeder

Figure 3. An image of a chick resting in an open feeder.  Note the fecal droppings inside the feeder (Picture Credit: Dr. Lloyd Weber).

General Good Practice for Coccidiosis Management During Rearing

Atmospheric Barn Environment: Get to Know Relative Humidity (RH) - Because barns require ventilation, the outside temperature and humidity can impact the environment of the barn; especially if the equipment does not measure and account for RH of the air feeding the barn.

Example of the minimum outside temperature needed paired with the temperature gradient needed in a generic chicken barn over the first 3 weeks of rearing (whole house brooding [1]) to achieve an RH of 35% inside the barn (if air handling equipment does not control the RH of the air feeding the barn).

 

Day 1

Day 3

Day 6

Day 9

Day 12

Day 15

Day 18

Day 21

Day 24

Day 27

 RH (%) inside the barn

 35

 35

 35

 35

 35

 35

 35

 35

 35

 35

 Temperature inside barn (°C)

 30

 27.8

27.2

26.1

25

23.9

22.8

22.2

21.1

20

 

Dew point outside barn (°C)

 13

 10

10

9

8

8

7

6

5

4


Click HERE to calculate Relative Humidity.

There is not a designated optimal relative humidity percentage set-out for oocyst sporulation but an RH of 35-70% is considered adequate (bird management guides recommend between 60-70%). Interestingly, good monitoring of RH may also help the welfare of the bird (2).

Atmospheric barn environment: Oxygen Access and Litter - If the oocyst does not have adequate oxygen access during sporulation, it may not become infective. Accumulation and compaction of litter can decrease oxygen access which can act to stop sporulation. In addition, high ammonia levels resulting from accumulated litter can also kill oocysts.

Physical Barn Environment: Leaky Drinkers - A nipple drinker in a broiler barn can have at least 1 million hits during an entire growing cycling. This wear and tear on the drinker over time can cause the drinkers to leak. Leaky drinkers cause localized areas of high moisture which can be a good spot for above average oocyst sporulation. Be cautious of these areas as there may be infective oocyst build-up.
Birdonlitterleakydrinkeranddirtycup

Figure 4. Examples of leaky drinkers and dirty drinker cups (A-C) for birds reared on litter.  Be cautious of localized areas of high moisture due to leaky drinkers (B, C) and dirty drinker cups (A) that can be potential reservoirs for oocysts (Picture Credits: Dr. Lloyd Weber).

References

1. Anonymous. Ross Broiler Management Manual. In. Aviagen. 2009.  Access HERE.

2. Stamp Dawkins, M., C.A. Donnelly, and T.A. Jones. Chicken welfare is influence more by housing conditions than by stocking density. Nature 427:342-344. 2004.