Top 10 health concerns for layers and pullets

U.S. layer and pullet flocks are generally healthy, but veterinarians have ranked the most commonly occurring diseases and syndromes for both cage-housed and cage-free layers and pullets. Cannibalism and E. coli infections rank as the top two health concerns for both cage-housed and cage-free layers, according to a survey conducted by the Association of Veterinarians in Egg Production in the fall of 2012.

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Cannibalism and E. coli infections rank as the top two health concerns for both cage-housed and cage-free layers, according to a survey conducted by the Association of Veterinarians in Egg Production in the fall of 2012 (see Table 1). The survey asked veterinarian members to rate the prevalence of each of the identified health issues on a scale of zero to three. A rating of zero means that the health problem is not seen, one means it is seen but not common, two signifies that it is commonly seen, and a rating of three is for a health problem that is seen in a majority of flocks.

Preventing cannibalism

Dr. Daniel Wilson, corporate veterinarian, Rose Acre Farms, said that cannibalism, which was identified as the number one health problem for layers, is a learned behavior for the hens whether they are housed in cages or on the floor. Survey respondents report that cannibalism is more prevalent in cage-free hens (scoring 2.06 in the survey) than in cage-housed flocks (scoring 1.52 in the survey). Wilson told the audience at the Pullet and Layer Health Workshop at the Midwest Poultry Federation Convention that cannibalism is primarily a management issue. He said that maintaining the appropriate light intensity is important; houses that are too bright can experience higher levels of cannibalism.

Inadequate beak trimming can make each peck more damaging to the bird being pecked, and this can increase the likelihood of bleeding, which can escalate pecking. Wilson said that giving timely feedback to the hatchery regarding any beak trimming issues is important for making sure your next flock is trimmed properly.

Some nutrient deficiencies can also contribute to cannibalism. Feed issues should be ruled out as a cause if cannibalism is a problem in a flock.

Wilson said that primary breeders are considering bird behavior when making selection choices for future generations of layers to reduce cannibalism. Genetic selection will likely become even more important for the layer industry in the future as some countries are moving towards banning beak trimming and as more cage-free housing systems, which tend to have higher cannibalism rates, are employed.

Controlling dust

Wilson said that avian pathogenic E. coli infections in layers can be caused by dust in layer barns. Layer houses tend to be dryer now as egg producers strive to control flies and ammonia levels by keeping manure in pits dry. He said that workers in layers houses have to be careful about using backpack blowers to remove dust from equipment, walls and ceilings when birds are in the house. The dust, which may contain fecal particles, can settle up on top of feed troughs and be ingested by the birds or can be inhaled by hens while the dust particles are airborne. If your workers need to wear a dust mask when cleaning, then you are probably stirring up more dust than the birds need to be inhaling.

Wilson said that infectious bronchitis disease and Mycoplasma gallisepticum issues in a flock can lead to secondary E. coli infections. He also said that growers should monitor the quality of the water the birds are drinking to make sure that it is not contributing to E. coli problems. Depending on the water analysis, some form of water treatment like chlorination may be useful.

For farms with repeat E. coli problems, Wilson said that a live E. coli vaccine is available for pullets. He also said that an inoculum feed additive based on the E. coli isolated on your farm can be fed to subsequent flocks to help control the E. coli.

Access to feces and parasites

Taking birds out of cages and putting them in aviary and floor systems gives hens and pullets more direct access to manure. Veterinarians ranked round worms, coccidiosis and bumble foot as the third, fifth and sixth most common health issues, respectively, for cage-free layers, and none of these three made the top ten for cage-housed layers.

Wilson said, “We always have to be aware that while we focus on our key issues in layers there is always the chance that some of these oddball diseases could pop up, particularly as we have changes in housing systems.” The reemergence of some diseases in layers can happen even when birds are still in cages. At the Midwest Poultry Federation Convention, Dr. Eric Gingerich, technical services veterinarian, Diamond V, said that coccidiosis can be seen in manure belt houses and in houses with drop through cages. The plenum used to move air to dry the manure while it is on the belt can become a spot where manure collects on top of it and provide access to the manure for the hens.

The addition of scratch areas and nest pads in enriched cages can also increase the hens’ access to fecal material. As producers change from deep-pit to belt houses and/or enriched systems, they need to be aware that coccidiosis control measures may become more important.

Gingerich said that flies and beetles can carry oocysts up from the pit and put them in areas where they can be ingested by hens. Airborne dust that settles out in the feed trough can also carry oocysts—another good reason to try and keep dust levels low in the layer house.

Coccidiosis problems in the layer house can reduce bird performance and feed efficiency as well as lead to secondary infections like necrotic enteritis, which Gingerich said can cause significant mortality. The only approved treatment for coccidiosis when the birds are in lay is Amprolium, which can be used in water or feed. He added that Bacitracin can be used if necrotic enteritis affects the flock.

T horough cleaning and disinfection of the layer house between flocks is important for coccidiosis control, Gingerich reported. He said that leaving feces on equipment in places the birds can reach will expose them to oocysts from the prior flock. Having a high enough light intensity during the spray vaccination at the hatchery will encourage the chicks to groom each other and ingest the oocysts in the vaccine. Some pullet growers will install paper trays on the floor on part of their cages to allow manure to buildup and allow for cycling of oocysts through birds in the cages so that they develop immunity in the pullet house. If the birds develop immunity in the pullet house, it will result in coccidiosis being less of a problem in the layer house, and this is particularly important for birds housed in cage-free systems.

Pullet health

For cage-housed pullets, the top two health issues are yolk sac infections (omphalittis) and starve-outs (see Table 2). For cage-free pullets, yolk sac infections, starve-outs and coccidiosis finished in a tie for the most prevalent health problem. Prevention of bacterial infection of the yolk sac needs to focus on hatchery sanitation and on hatching egg quality. Wilson said that today most layer chicks are given a prophylactic antibiotic injection at day of age, but that this might not be an option in the future. Because of this, hatchery sanitation and egg shell quality will be even more important in the future.

Wilson said that starve-out chicks can be identified post mortem by dehydration and lack of food inside the crops. He said that proper temperature control while chicks are transported from the hatchery to the pullet house is important for getting chicks off to a good start. Achieving the proper brooding temperature throughout the pullet house, whether in the top cage or the bottom cage or in cages facing the outside walls of the building, is critical for keeping birds active without dehydrating or overheating them. He said, “You have to check temperatures in the individual cages.” He also said that worker activity in the house plays a role in getting birds up and moving and finding feed and water.

Wilson said that it is important to communicate any problems with the chicks back to the hatchery and to correctly identify why the chicks are dying.

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