Submitted to: Western Poultry Disease Conference
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/1999
Publication Date: N/A
Citation: Interpretive Summary: Over the past several years there has been an increasing problem in turkey breeder hen candidates between 22-30 weeks of age. The hens are found early in the morning flipped on their backs. Most survive this ordeal, but mortality can be 1.5%. In addition, while on their backs, the resulting wing flapping can induce hysteria in unaffected birds, which can result in hens piling up, resulting in greater mortality. Several biochemical and hormonal profiles were investigated in the flipped birds. It was determined that affected hens have extremely low thyroid concentrations in the blood. It was also shown that this hypothyroidism is not due to stress. Low levels of thyroid hormones may lead to nervous symptoms resulting in flipping over. Further pathological analysis revealed that the thyroids of affected birds exhibited histological evidence of a thyroiditis condition similar to autoimmune disease. Whether the etiology of this condition is the result of an autoimmune condition awaits further study. This information will be of interest to other scientists and producers.
Technical Abstract: Over the past several years there has been an increasing problem in turkey breeder hen candidates during the late grow-out period between 22-30 weeks of age. Affected birds are usually found in the early morning flipped on their back. Some of these are found dead but majority of them survive for variable period of time. Average mortality is 1.25%. The incidence is particularly increased during the winter months. Studies have been carried out to determine the pathogenesis of this syndrome. Extensive pathological examinations, body compositions, blood gases, biochemical and hormonal profiles have been performed. The results showed that affected hens have extremely low concentrations of thyroid hormones T3 and T4. This hypothyroidism seems to be transient. We have also shown that this transient hypothyroidism is not a result of stress.