Attention to biosecurity on the farm will give healthy baby chicks more opportunity to thrive.
Photos by Keith Weller, courtesy of USDA-ARS.
Raising chicks, whether they're broilers, hens for egg production or fancy birds for exhibition, can be a rewarding hobby or part of a farm enterprise. One of the most important aspects of maintaining healthy birds is ongoing disease prevention and thorough biosecurity.
Several major diseases of poultry can be avoided if birds are properly immunized. Poultry vaccines are usually sold in large quantities, so it's best to have vaccinations done at the hatchery whenever possible. Most hatcheries offer vaccinations prior to shipping chicks, and it's a good idea to pay a little extra for that service. If you purchase chicks from a neighbor or an auction, they most likely won't be vaccinated and biosecurity will be even more critical.
Although chicks that come from reputable hatcheries are likely to remain healthy, they are still vulnerable to disease throughout their lifetime.
Exotic Newcastle disease, or END, is a highly contagious and fatal disease that affects birds of all species, including wild birds. END is caused by a paramyxovirus and is transmitted via aerosols, other birds and fomites. The END virus can survive in poultry houses for as long as a year and can also survive freezing, but it is sensitive to disinfectants and exposure to sunlight. Although END is rare in the U.S., smuggled birds (such as Amazon parrots) can bring the disease into the country.
Marek's disease is a herpes-type viral infection of domestic chickens seen in all parts of the world. Young chicks (under 16 weeks) are highly susceptible to Marek's, and once infected, they cannot be treated. The neurological form involves the central nervous system and results in "floppy broiler syndrome" and associated paralysis. The visceral form causes tumors in internal organs, and the cutaneous form results in tumors of feather follicles. Marek's is highly contagious and is spread through respiratory secretions.
In tests at the Beltsville laboratory, a vaccine injection is used to immunize chicks against coccidia with recombinant DNA containing two promising proteins from the outside coat of oocysts, the protozoa's infectious stage.
The vaccine for Marek's disease can be administered to chicks on the day of hatch. Vaccinated birds can still become infected with the Marek's virus, but the vaccine prevents the appearance of tumors and paralysis associated with Marek's.
Coccidiosis, caused by various species of the protozoan Eimeria, is a common problem for both small and large flocks. Chicks between 4 and 8 weeks old are most susceptible and acquire coccidia through direct or indirect contact with infected droppings. Wet litter, dirty conditions, pre-existing disease and poor nutrition are the most common triggers of coccidiosis, but good husbandry doesn't guarantee healthy birds. Coccidia can survive outside the animal's body for a long time, and can be introduced through free-flying (wild) birds, contaminated footwear or clothing, rodents and equipment. Signs of an outbreak include birds that appear to be uncomfortable or droopy, huddling with other birds, lack of appetite and diarrhea.
There are two ways to manage coccidiosis: vaccination or using medicated feed that contains a coccidiostat. Organic growers should check with their verifying agency to see if the vaccine offered at the hatchery meets organic requirements. Vaccinated birds develop full immunity to coccidiosis and should not be fed medicated feed.
Blackhead, another protozoan disease of poultry, affects the ceca and liver. The causative organism is shed in the fecal material of chickens, turkeys and game birds. Chickens can be infected with the blackhead organism without showing signs, but shed organisms while infected.
Most of these diseases can be prevented through vaccinations, usually done at the hatchery. Purchasing birds at auctions is risky, especially if you already have healthy birds at home. It's risky to accept "free" birds from friends unless you know for sure how those birds have been raised and maintained. One infected bird from a neighbor can introduce disease and wipe out your entire flock. It's also important to watch your birds carefully for signs of illness, and remove and isolate sick birds from the group as soon as possible. Birds of any age that are exhibited at shows should be isolated upon return to the farm for at least 10 days and watched carefully for signs of disease before they are returned to the flock.
Ideally, groups of birds, especially those started as newly hatched chicks, should be kept as an original unit without adding any birds to the group. Whenever possible, chickens, turkeys and other poultry species should be housed separately, especially when they're young. Avoid borrowing or loaning poultry equipment unless it is thoroughly disinfected with an approved product. Prior to disinfecting, remove all organic matter from surfaces so that the disinfectant can work properly. Items made of wood, cardboard and other permeable materials are almost impossible to disinfect properly.
If you visit a neighbor who raises poultry, be sure to disinfect your shoes before walking among your own birds. It's best not to allow others who raise birds to have access to your birds, but if you do, make sure they use disinfectant on footwear before and after visiting. Ask your veterinarian to recommend appropriate disinfectant products for boots and equipment.
The author is a frequent contributor and freelance writer who farms and raises Great Pyrenees in south-central Pennsylvania.