Comparative gait analysis of two strains of turkey, Meleagris gallopavo.

1. Economic requirements have encouraged farmers to select broad-breasted strains of turkeys (Meleagris gallopavo). These birds are very heavy (more than 30 kg), have pectoral hypertrophy and are frequently lame. Traditional turkeys, closer to wild birds, weigh 9 kg on average. 2. Gaits, which are motor pattern expressions, seem to be linked to species morphology. However, no significant differences are evident between the gaits of traditional and broad-breasted strains. 3. Yet, posterior views of the walk of both strains show lateral oscillations, which are very slight in the traditional one but very marked in the broad-breasted one. 4. In the latter, modification of the centre of gravity path may increase the energetic cost of walking and be associated with problems of lameness. 5. Therefore, if the genetic pool permits an increase in weight of broad-breasted turkeys, then extrinsic factors, such as gravity constraints, may limit this evolution.