Resources

PLT is normally applied to litter prior to chick placement to control ammonia during brooding when ventilation rates are low. However, mid-flock PLT application has proven to be a beneficial strategy to control ammonia after bird placement while also improving bird health, reducing disease severity and increasing flock productivity.

Published research demonstrates that mid-flock PLT application is safe and effective at controlling ammonia, which can severely stress the respiratory system of birds.

During a pen study in Mississippi, PLT was applied once or twice depending on group during broiler rearing in addition to the first application prior to chick placement (day -1) (Purswell et al, 2013).
Ammonia volatilization was greatly reduced as additional PLT applications were performed (Chart 1).

In addition to ammonia control, mid-flock PLT application has been shown to improve bird health and performance.

A study conducted in Delaware, in both research houses and commercial houses where mid-flock applications of PLT were performed, showed improvements in average livability, weight gain and foot pad quality (Table 1 and Table 2).

In addition, houses receiving multiple applications of PLT used less gas and electricity due to lower ventilation requirements to remove ammonia from the houses. Since PLT binds ammonia in the litter, the nitrogen content of the litter was higher when additional PLT was applied, thus increasing the fertilizer value of the litter (Hong et al, 2013; Zhang et al, 2016).

Mid-flock PLT application has been utilized in the field by producers for many years, particularly to combat bacterial challenges such as dermatitis (caused by Clostridium perfringens), E. coli infections, and even Enterococcus. It is well-known that by lowering litter pH, the growth rate of pathogenic bacteria is greatly inhibited, thus reducing the bacterial load of the litter. More recently, PLT has been used by producers to aid broiler flocks through avian metapneumovirus (aMPV) infections. It is generally thought that the majority of bird mortality and production losses during aMPV infections are due to secondary bacterial infections, particularly E. coli.

In the spring of 2025, a broiler company that had been experiencing repeated aMPV infections on the same farms decided to utilize mid-flock PLT application in houses that had previously tested positive for aMPV. If a particular house tested positive for aMPV and significant bird mortality was observed, mid-flock PLT application was scheduled for the next flock. Since birds were typically showing clinical signs of aMPV infection around 30 days of age in previous flocks, mid-flock PLT application was scheduled for 25–28 days of age. In addition, PWT (pH Water Treatment) was also administered in the drinker lines at a target water pH of 4 for 2 to 3 days starting the day of mid-flock PLT application. PLT was applied at 100 lb/1,000 ft² in this program, but rates up to
150 lb/1,000 ft² have also been successful when it was deemed necessary.

The results of this program were very successful. While the 30 houses that received mid-flock PLT application once again tested positive for aMPV according to PCR testing, dramatic improvements in bird performance were observed. Farms that received mid-flock PLT application after being aMPV-positive in the previous flock finished with 3.3% better livability, 0.80 lb heavier body weights, and reduced feed conversion by 0.13.

In general, additional mid-flock PLT application is most effective at reducing the losses from disease challenges when done before clinical disease signs are observed. Once a flock is showing outward signs of an infection, and mortality may have already increased, it may be too late for mid-flock application to be as effective. Therefore, mid-flock PLT application should be utilized as a preventative measure for helping to reduce the impact of a potential disease challenge rather than a treatment attempting to cure a disease once it has negatively impacted a flock.

PLT may be applied mid-flock using manual spreaders or small hopper systems, but when available, custom applicator services offer the fastest and least labor-intensive option. The primary goals during mid-flock application are to minimize bird stress, prevent piling and ensure adequate ventilation. Using sufficient labor and maintaining bird movement are critical to a successful application.