Western
Meeting of Poultry
Clinicians and Pathologists
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Clinicians and Pathologists
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Experimental Reproduction of Torticollis in Meat Type Chickens C. Riddell Western College of Veterinary Medicine University of Saskatchewan Since 1993, torticollis has been recognized in broiler breeder cockerels in six different flocks on four different farms in Western Canada. Four different strains of breeders have been affected. The deformity has been recognized as early as four weeks of age. More affected birds are recognized as the flocks grow older. Some affected birds have been culled as late as 55 weeks of age. Total cockerels culled have varied from 2 to in excess of 10 percent. In affected birds, cervical vertebrae have malformed articular facets, uneven arches and misshapen vertebral body articulations. No significant microscopic lesions have been found in cervical muscles, spinal cords or brains from affected birds. A similar deformity was recognized in experimental broiler breeder cockerels fed a low protein diet at Guelph in 1982 and in experimental broilers fed low protein diets at Saskatoon in 1987 and 1988. Australian workers have reported similar neck lesions in broiler breeders with low protein diets (Personal Communication). This brief report describes experimental reproduction of the lesion in male broiler chickens. 624 chicks were placed in 12 pens, 52 chicks to a pen, and fed three different diets. The first or control diet was a standard starter diet based on wheat and soya bean meal and was calculated to contain 17.1% protein. The second or deficient diet contained mainly wheat and was calculated to contain 10.9% protein. A third intermediate diet was calculated to contain 14.3% protein. All diets contained the same mineral and vitamin supplements. No marked differences in performance were noted between birds on the control and intermediate diets. Average weight on the deficient diet at 6 weeks when the experiment was terminated was 154 grams. Total loss mainly due to culling and some early mortality was 6 birds (3%) on both the control and intermediate diets and 41 birds (20%) on deficient diet. The major causes of culling of birds on the deficient diet were 14 birds with torticollis, 5 birds with ventral deviation of the head and 10 birds with rotated tibia. Major abnormalities were found on microscopic examination of the growth plates of these deficient birds suggesting the primary lesion may be in the skeleton. These results do not prove that the problem with torticollis in commercial broiler breeders is due to a protein deficiency, but support the concept. Whether the problem results from a deficient diet, excessive feed restriction or a combination needs to be resolved. When the problem has been encountered in Australia, increasing the protein level in the diet has controlled the problem (Personal Communication).
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