Two poultry veterinarians recently offered practical advice for reducing disease risk in poultry environments.
“I’ve heard that 90% of our problems in poultry houses are management related,” reported Eric Shepherd,* poultry veterinarian. “The other 10% requires a veterinarian. It comes down to the basics that are often overlooked and make disease worse.”
Shepherd and Brian Fairchild, DVM, University of Georgia, spoke in a webinar sponsored by the Poultry Science Association and American Association of Avian Pathologists.
Highlights of their advice are presented in six tips they gathered while working with poultry farms.
1. Make feed time as easy as possible
Some things, like hunger, are beyond a grower’s control. “We feed-restrict broilers while their genetics make them want to eat,” Shepherd said. “When a feeding is skipped, they’re hungry, so don’t make these birds panic looking for food. Try to make feed time as easy as possible.”
He recalled a farm that struggled to fill a long line of pans with feed. Pullets ran around trying to find feed, which had not been distributed to all the pans. As a result, birds piled on each other while trying to eat from pans with feed.
“This company farm consistently had scratched-up pullets with poor uniformity,” Shepherd said. “They were able to make some feeding changes, and the problem was minimized. But even if you fix feeding issues, you may need to coax pullets to go to the end of the line for feed.”
Migration fences should also be used with every flock to spread out birds evenly in houses. “You will get your correct birds per pan and per nipple while also helping airflow,” he added.
Feed-restricted and hungry birds may resort to undesirable practices, like cannibalism. “Some lines of hens will attack each other if you don’t have your feeding right and will eat somewhere else,” he said.
A fiber source added to feed may help reduce hunger and stretch out feeding time, Shepherd suggested.
2. Minimize scratching opportunities
“Any time birds go off feed, they pile on each other at the pans and get scratches,” Shepherd said. “Those scratches really manifest on the broiler side. We end up seeing an inflammatory process and then dermatitis.
“Anytime you have something that encourages scratching, it’s going to make dermatitis very difficult to get rid of,” he added.
3. Watch for calcium tetany issues
Calcium tetany is a feed-related condition that can arise in breeders. The condition is caused by inadequate calcium, leading to muscle weakness and paralysis.
“A typical case of calcium tetany is a 30-week-old breeder flock at peak demand age, and it’s hot outside,” Shepherd said. “Basically, the birds get respiratory alkalosis from panting, which interrupts calcium utilization in these hens. And calcium is not just important for eggshells but also for life functions. It’s a big part of how muscles work.”
Producers can confirm the condition with a rapid blood calcium test.
“The next step should be getting your house cooled down with fans going even before the birds eat,” he continued. “Make sure your water flow keeps up with peak usage. And get those hens fed, watered and off those slats.”
4. Maintain quality litter
“I focus on litter quality because it has such a big impact,” Fairchild reported. “Diet affects litter. We’ve seen little mishaps at a feed mill, such as too much salt in the diet. The excess salt led to very damp bedding from increased fecal material.”
Bird disease impacts litter quality, especially enteric disease and viral challenges. “A lot of moisture in the fecal material can increase moisture in the house and make it more difficult to maintain the house environment,” he explained.
Bird density also affects litter. Housing is designed with an even distribution of birds throughout it. “If we get 60% of the birds in the front of the house and only 40% at the rear, it’s more of a challenge for food and water at the front than the rear,” Fairchild added.
Drinker management is also important for litter quality. Keep the drinker-line height adequately raised for birds to reach, he advised. Water pressure also needs to be adjusted according to bird age and to meet demand.
“If we get too high on water pressure, then we’ll end up with more water coming out of the drinker than what the beak can hold,” Fairchild said. “Water will be on the floors and will contribute to the moisture load in the house.”
5. Manage litter disease challenges
Recent research examined the impact of litter depth on litter condition and footpad dermatitis. Fairchild said deeper litter produced drier conditions and lower moisture content, which led to better overall footpad scores.
The type of material also affects litter quality. “We looked at different bedding materials, and some are more moisture-absorbent than others,” he explained. “A material like sawdust is pretty absorbent and can hold and release moisture. We can get by with 4 inches (10 centimeters) of it for bedding.
“Using something that’s less absorbent, like rice hulls, needs a deeper base,” he continued. “You might want to use 5 to 6 inches (13 to 15 centimeters) of bedding to be able to handle the moisture load from birds as they age.”
Pullet houses are typically dry and dusty due to their lower density and restricted feed and water. “With less overall moisture going into the litter, poor cocci cycling occurs,” Shepherd said. “In the US, we use restrictive house brood with a quarter house or a third of a house to get more moisture in a certain area.”
To help stimulate cocci cycling, most broiler breeders are on a coccidial vaccine, he added.
In the winter, litter tends to become too wet, which leads to health problems ranging from viral infections to Escherichia coli.
“I was told once that a little air goes a long way,” he said. “The best thing to do is get ahead of it and move some air to air it all out.”
6. Focus on relative humidity
Controlling moisture in poultry buildings is important because ammonia is a symptom of high moisture and can lead to many bird health problems.
“We want our ventilation rates to control moisture,” Fairchild said. “We recommend focusing on relative humidity and keeping it below 60%. We need to remove the moisture that birds add each day to prevent moisture from building up.”
Fairchild cited research that supports the importance of relative humidity. A study published in 1990 looked at three relative-humidity treatments and the impact on the incidence of birds with twisted legs.
“As the relative humidity increased, so did the incidents of lame birds in those treatments,” he explained. “As more ammonia is produced due to wet litter, more challenges occur in the birds.” Relative humidity of 45% produced 6.5% lameness, and 75% relative humidity produced 9.1% lameness.
Other studies reported that higher levels of ammonia increase susceptibility to disease. “Most people understand we now need to keep ammonia levels below 40 parts per million (ppm) or less,” Fairchild said. “A lot of animal welfare guidelines use 25 ppm.
“This is a challenge our growers face because it’s going to cost money, not only on electricity to run fans, but to reheat the air we bring into the house as we remove the ammonia through ventilation,” he noted. “But we know that ammonia is undesirable, and we want to try to control that the best we can.”
Fairchild suggested growers use a smartphone app called “Poultry411” to help calculate ventilation rates, including relative humidity.
“If you keep relative humidity below 60%, your air quality is going to be good,” he added. “The drier you want your litter, the lower we want the target relative humidity to be. Relative humidity of 70% is damp litter, and 40% is dry litter. Somewhere between 50% and 60% is moderate moisture control.
*Eric Shepherd, DVM, senior technical services veterinarian, Zoetis
