In the U.S., cage-free currently represents about 18-20% of egg production with a significant increase expected in the next five to six years. As with any new production model, experience serves to help management practices evolve over time. While litter management is a non-issue in caged layers and a significant issue in broiler production, litter management for cage-free has different considerations.
Most cage-free flocks begin on new litter and are fed diets that serve to maintain bone strength (high levels of calcium and phosphorus), which keep nitrogen excretion low. While this serves to keep ammonia generation low, it is still present. Given that ammonia can detrimentally impact health and performance at levels as low as 20 PPM, ammonia control is a vital part of environmental management.
Frequent application (every other week) of low rates of PLT® litter amendment will not only serve to bind ammonia, it increases the nitrogen content of litter in the process, raising the value of litter as a fertilizer source. Safety and flexibility are key considerations when selecting litter amendments for cage-free. PLT® is non-hazardous and can be applied at any time, even with birds in the house.
Hens remain in the house for up to 80+ weeks allowing for a significant amount of manure, feed and other organic matter to accumulate on the floor. Producers must consider the type of environmental challenges that litter presents to birds, especially during times of stress.
For example, using an acidifier to lower litter pH during vaccine administration periods can help mitigate stress. Once birds are in lay, reducing litter pH for improved litter hygiene can benefit floor eggs.
Humidity and coccidiosis.
Litter, humidity and coccidiosis cycling are irrevocably linked. Humidity is often naturally low in floor-raised pullet houses, as these birds consume less feed than broilers and therefore drink less water, creating a low humidity environment.
Following initial coccidiosis vaccination, the development of immunity is dependent on birds’ ingestion of oocysts that are shed into the litter following the initial vaccination life cycle. Subsequent cocci cycling, often two to three cycles, must be completed in the flock to develop immunity. Oxygen, temperature and moisture are the three main variables that impact this process. In order for sporulation to occur, oocysts need a minimum of 20-25% moisture.
“Oxygen and temperature are almost a given in our production systems, so truthfully litter moisture will be your primary determinate of success and failure of coccidiosis immunization.”
– Brad J Turner, DVM, MAM of Poultry Research Partners
“With long lived animals like layers, it’s critical to get them immunized to cocci so they can benefit from lifetime immunity,” said Turner. “It’s a balancing act between maintaining bird health, suppressing the bacterial challenge, but also having enough moisture in the litter to allow for adequate cocci immunization.”
There are multiple species of Eimeria, the causative agent of coccidiosis, that infect poultry. Without sufficient humidity to allow for sporulation, the life cycle of Eimeria species slows or stops, which can result in uneven immunity development. For the most damaging species such as Eimeria maxima, this can lead to highly uneven birds within a flock, which makes flock management very difficult.
Managing litter for optimal cocci cycling
While it’s best to avoid management practices such as tilling that overly dry litter, it’s also important to not introduce too much moisture. “About 20-25% moisture, no more than ¼ inch below the surface of the litter, is needed to induce enough sporulation,” said Turner. “Too much moisture can cause excess reproductive cycling, which can invade the intestinal lining of the birds and create damage.”
Turner noted that commonly used litter management tool, PLT®, is hygroscopic, which means that moisture is drawn from within the litter “increasing availability of moisture at the surface where it can be utilized by oocysts.”
It’s important to note that PLT®, which is commonly used for pH manipulation, can be utilized without impact to cocci immunization. “There is no known interaction of pH with coccidiosis,” said Turner.
As industry investment in cage-free layers increases, so will the search for intuitive solutions that address the common challenges of this production model.