Look out for these common broiler chicken health issues. Broiler chicken health problems primarily relate to rapid growth and heavy weight. Common issues for commercial strain broilers are lameness, breast blister, and heart failure. Among utility breeds, breast blister is the most common health concern.
Lameness
Commercial-strain Cornish-cross broilers are developed for such rapid growth that their bodies get too heavy for their little legs to carry them. Difficulty walking is therefore a significant issue among strains developed for industrial production. The faster a bird grows, the greater its risk of going lame.
During the past half century, the rate of industrial-broiler growth has increased from less than 1 ounce (25 grams) per day to today’s rate of 3-1/2 (100 grams) ounces per day. Where a broiler once took 13 weeks to reach 4-1/2 pounds (2 kilograms), today’s commercial broilers reach that weight in as little as five weeks. As a result of the strain on their legs and joints, those fast-growing birds can’t get around well, and a small percentage can’t walk at all. A study as early as 1972 concluded the “birds might have been bred to grow so fast that they are on the verge of structural collapse.”
When a broiler gets so heavy its legs can’t support its body, the bird can’t get to feed and water, leaving it to get trampled by the more mobile birds and eventually die of either starvation or dehydration. In industry, up to 2 percent of lame broilers must be killed before they reach market weight.
Although it shouldn’t take a PhD to see when a chicken is in distress, the broiler industry has devised various lameness scoring systems to determine when a review of management practices might be needed and at what point a lame bird should be humanely put down. The typical progression of lameness is:
- No lameness — the chicken walks freely, bending the toes of its raised foot as it walks
- Detectable lameness — the chicken is mobile but somewhat unsteady, and the raised foot may remain flat with spread toes
- Abnormal gait — the chicken is mobile, although one leg takes short, quick, unsteady steps (like a person with a sprained ankle)
- Severely impaired — the chicken doesn’t want to walk; if you stand it up, it may take a few steps before plopping down, perhaps struggling backward (backpedaling) on its hocks
- Completely lame — the chicken can’t stand up but may try to shuffle around on its hocks
When a chicken reaches the impaired stage, it may develop a kinky back. Too-rapid growth causes the vertebrae to twist and pinch the spinal cord. Typically, an affected broiler will arch its back, extend its neck, squat with its feet off the ground and its weight on its hocks and tail, and backpedal. The bird may fall over and be unable to get up, become paralyzed, and die from dehydration. The humane thing to do for impaired and completely lame broilers is put them out of their misery.
The best way to minimize leg-health problems in commercial-strain broilers is to reduce their growth rate. Some backyard broiler growers do so by removing feed overnight to decrease eating time during early-morning hours. A study published in 2008 by researchers at England’s Bristol University determined that broiler lameness also may be reduced by feeding whole wheat, which has the added benefit of improving digestion; reducing the number of hours the broilers are under light, thereby decreasing the amount of time they spend eating; reducing crowded conditions; feeding a nonpelleted ration, which increases the amount of time required to eat the same amount of feed. Of course, you could avoid the lameness issue altogether by raising a utility breed that doesn’t achieve the exaggerated growth rate of industrial broilers.
Breast Blister
Broilers that have trouble standing or walking spend a lot of time resting with their weight against their breastbone, or keel. The pressure of the breastbone against the ground causes irritation and inflammation, resulting in a large blister, also known as keel cyst, keel bursitis, or sternal bursitis.
Housing broilers on wire or on wet or hard-packed litter and providing roosts for heavy birds to perch on increase the chance that breast blisters will develop. Another factor is poor feather development, which results in fewer feathers to protect the breast.
Although a blister is uncomfortable, it does not pose a serious health risk unless it becomes infected. The blister may, however, mar the appearance of the bird’s meat.
Avoid blisters in utility breeds by keeping them on soft litter or grassy pasture and by not furnishing roosts. Avoid breast blisters in commercial-strain broilers by reducing their rate of growth using the same methods as would be used to minimize lameness.
Heart Failure
As short as the life of a meat bird is, commercial-strain broilers run the risk of dying prematurely from heart failure. Their little hearts and lungs simply can’t keep up with the exaggerated growth rate of their body muscles. The high oxygen demand of rapid muscle growth, coupled with too-little space for blood flow through the capillaries of the lungs, causes ascites — the pooling of yellowish or bloody fluids in the abdomen. The condition is thus commonly called broiler ascites, dropsy, or water belly.
Affected broilers grow more slowly, sit around with ruffled feathers and are reluctant to move, and may die suddenly from heart failure. This condition is more likely to occur in commercial-strain broilers pushed for maximum growth than in the same strain sensibly managed in your backyard. Like leg and joint problems, heart failure is not an issue for slower-growing utility meat breeds.
More from: Storey’s Guide to Raising Chickens
Excerpted from Storey’s Guide to Raising Chickens, Fourth Edition© by Gail Damerow. Used with permission from Storey Publishing.
