PREVENTING WINTER RESPIRATORY DISEASE
Broiler-house management and vaccination essential
Respiratory disease in broilers can occur any time of year. During winter, however, it is particularly problematic when air and environmental conditions could be compromised as producers try
keep costs under control.
Maintaining good air quality is essential and is heavily influenced by ventilation techniques. When a house is under ventilated, ammonia levels and litter moisture can rise to the point where it is detrimental to the birds’ health and predisposes them to respiratory disease.
Elevated ammonia levels damage the cilia, those brushlike structures responsible for clearing debris out of the trachea. When the cilia are damaged or destroyed, birds may succumb to viral infections such as Infectious Bronchitis (IB), Infectious Laryngotracheitis (ILT) or Newcastle Disease (ND). These viral pathogens can also cause ciliostasis, which can result in chickens displaying signs
of lethargy, depression or coughing and snicking.
Poor litter quality due to inadequate ventilation is favorable for bacterial growth. That’s why it’s not uncommon for birds that have a respiratory virus to develop a secondary bacterial infection - usually Escherichia coli - which can lead to severe polyserositis, septicemia and even death.
Evidence of respiratory disease can show up at the processing plant as well as in the poultry house. Condemnation due to airsacculitis, often due to an underlying respiratory disease, may trend upward during cooler months, when maintaining an optimal environment becomes a challenge. An increased number of birds with airsacculitis can affect the efficiency of the processing plant. More birds will have to be rerouted and salvaged for parts, which can slow the line speed, and that’s costly.
One trend that may influence ventilation practice is variation in house sizes. Today, many poultry growers are choosing to build larger houses to raise more birds more efficiently. However, methods traditionally used to ventilate smaller houses may not yield the same results in larger ones. Care must be taken to ensure that longer and wider poultry houses have the proper equipment and ventilation settings necessary to adequately move and exchange air. Air has to travel further, and if airflow is uneven, birds at one end of the house might have fresh air while birds at the other don’t.
Poorly maintained equipment can lead to difficulty in heating and ventilating the house. Old and unmaintained fans might still run, but that is no guarantee that the cubic feet of air moved per minute is the same as it was when the fans were first installed. A fan may not move the required amount of air if shutters are dirty and belts need replacing. Air flow can be easily monitored using an air flow meter. Proper and→
regular maintenance is critical to make sure the systems are working properly.
Computerised, automated systems with preset programs are handy and can work well if used appropriately. Advancements in farm equipment make it easy for growers to monitor the house condition and ventilation settings without having to enter the house. However, never assume birds are comfortable just because the computer indicates everything is running smoothly. There is no one-size-fits-all setting since the conditions for keeping birds comfortable and healthy can vary flock to flock. Because of this, it’s important to look at the birds regularly to make sure they are comfortable. Visually checking birds is a fail-proof way to confirm that house conditions, including ventilation and litter quality, are appropriate. Check ammonia People who spend a lot of time in poultry houses can easily become desensitized to the smell of ammonia and may not realize these levels are too high for bird health. A highly sensitive human nose is capable of detecting ammonia at a concentration as low as 1 ppm. For poultry, it’s imperative to keep levels below 25 ppm to prevent a loss in performance and increase in disease - and to protect the safety of workers.
Ammonia levels should be monitored routinely throughout the life of the flock, and if they’re too high, ventilation settings must be adjusted to reduce ammonia concentration. There are several different tools available for evaluating ammonia levels; just ensure that the tool chosen yields consistently accurate results.
Avaccine program tailored to help protect against respiratory disease risks is essential and should be individualised, taking into account risks on the farm and in the geographic area.
Infectious bronchitis virus (IBV), for example, is always a concern for broiler flocks, and the key to protection is identification of the IBV strain that’s circulating. Diagnostic methods such as serology, hemagglutination inhibition and polymerase chain reaction analysis can determine the most prevalent IBV serotypes in a flock.
Sometimes a heterologous program (using vaccines with different serotypes) may help provide cross protection in the field. Proper vaccination programs play a major role in helping to provide protection against these diseases.
In summary, vaccination along with managing the environment is crucial for maintaining bird health. For many growers, desirable ventilation can be challenging in cooler months, especially due to high energy costs. However, inadequate ventilation puts birds at risk for respiratory diseases that can lead to high rates of morbidity and condemnation. Initiating good management and a solid vaccination plan are often more cost effective in the long run.¡