In-house litter composting, or windrowing, has emerged in the past few years as another option in the toolbox of litter management practices to reduce pathogen challenge and improve broiler performance.
Typically completed during the downtime between broiler flocks, litter windrowing is a practice that has found a niche within the industry. While the process can be time consuming, windrowing litter has been shown to benefit bird performance and health.
Based on research and field observations on Delmarva and in the southeastern United States, this article presents current guidelines for windrowing litter between flocks. These guidelines are based on the use of windrowing equipment and on Mid-Atlantic and Southeast production practices, housing and climate. Procedural modifications may be needed for other regions, climates or litter management practices.
The ideal time to start in-house windrowing is the first flock following a total cleanout. If starting with built-up litter, it is best to implement windrowing during warm or moderate weather. This allows for increased ventilation to control the initial flux of ammonia following windrowing on built-up litter and for first-time windrowers to acclimate to the needs and nuances of the process.
At minimum, 12 to 14 days of layout is needed to implement the windrowing procedure. Windrowing should be avoided if there is inadequate layout time as sometimes occurs during summer flocks or in extremely cold weather that does not allow adequate conditions for moisture and ammonia removal.
Windrowing should be implemented within two days following bird movement to capitalize on the moisture and heat within the litter at the time of catch. This will enhance the rapid rise in windrow litter temperature. Only with extremely dry litter will adding additional moisture to the windrow be necessary to achieve desirable temperatures. The depth of the litter pack is an important point to consider. Ideal litter depth is in the range of three to six inches. If the litter depth exceeds six inches, a portion of the litter should be removed prior to windrowing. Deep litter can be more difficult to manage from a moisture removal and ammonia control standpoint. The cost and effectiveness of windrowing is also negatively influenced with deep litter.
The optimum windrow size is 18 to 24 inches high and conical shaped. This litter volume heats rapidly, is easy to turn and allows for maximum moisture and ammonia release. The number of windrows per house will depend on litter depth and house width.
If caking exceeds three feet wide and/or three inches thick under the drinker lines, it may be beneficial to de-crust the house after the windrowing process. During cold weather it may be necessary to remove excessive cake before building the windrows or de-crusting the house after leveling the litter to minimize ammonia volatilization during brooding.
Since one of the benefits of windrowing is exposing the dirt floor to the atmosphere, as much as practical, removing all litter and hard pan from the floor is generally recommended. In cold weather, it would be best to remove this hard pan from the house. In warmer weather and with dry litter, the hard pan may be incorporated into the windrow as an added source of moisture.
Working the litter
From a pathogen reduction standpoint, the goal is to reach at least 130 F and sustain a high temperature for a minimum of three to four days. Exposing all the litter to high temperature is needed to reduce or eliminate pathogens. An inexpensive digital thermometer with a 1-ft long probe inserted into the top of the pile is one option for monitoring windrow temperatures.
Three to four days after construction, the windrows should be turned. It is best to turn windrows at least once and several times if possible before leveling. All litter, including that under the windrow base should go through the heating process. Turning helps release moisture and ammonia, increase exposure time to high temperatures, reduce cake and increase the percentage of pathogen kill in the litter mass.
For farms with a significant disease challenge, it is best to remove all litter from the sidewalls and corners and incorporate this litter into the windrow. The entire windrow should be shifted during the turning process to expose the litter mass to high temperatures and the floor to the drying effects of the atmosphere. A building wash down prior to windrowing will help incorporate any pathogen-laden dust into the pile. For farms with significant disease challenge, it may take two consecutive windrowing events (flocks) to break some diseases (i.e., dermatitis) and prevent re-occurrence.
Completing the process
Darkling beetles will start migrating to the surface of freshly windrowed litter within an hour after formation. An ideal time to get maximum beetle kill may be to apply an insecticide to the windrows within the first six hours after pile formation. Application along the sidewalls should be considered if this litter is not incorporated into the windrow. There may be an opportunity to decrease the frequency of insecticide applications since high windrowing temperatures also aid in reducing darkling beetle populations.
Closing up houses following windrowing to retain heat will have little impact on windrow temperatures. More importantly, in a closed house there will be very high (and dangerous) levels of ammonia, carbon dioxide and moisture. Depending on ambient weather conditions, the end doors should be open, minimum vent fan(s) should be set on a timer or a tunnel fan(s) should be set on temperature. Circulation fans should be kept on to help move the air and dry down the litter. Ventilation to remove ammonia and moisture should be provided from the day of windrowing until chick placement. When the windrows are being turned, maximum ventilation should be provided to help remove the moisture and ammonia as it being released from the steaming piles.
The windrows can be spread out and leveled with a front end loader, blade or some types of windrowing equipment. A box blade with an adjustable skid works well to achieve consistent depth. It is critical that adequate time be devoted to leveling and cooling down the litter. Leveling the piles at least four days prior to chick placement is recommended.
To minimize the potential for high ammonia levels in the subsequent flock following windrowing, it is essential to follow the steps described in this article. Increased application of a litter amendment (25% plus) may be required to suppress ammonia, particularly in cool weather. Higher ventilation rates may also be needed during brooding to control ammonia. Failure to control ammonia during brooding can result in poor performance and partially defeat the benefits of the windrowing program. Ammonia control tends to be more manageable after a few flocks once a windrowing program is initiated.
While the windrowing process may not be for everyone due to the time and labor requirements, windrowing litter between flocks has the potential to improve broiler performance and health, particularly on farms with chronic disease challenges.