[Effect of locomotor activity on leg disorder in fattening chicken]

Leg disorders have become a major concern in comercial poutltry meat production. The mechanisms which cause leg problems are not completely understood. It has been hypothesed that high growth rate and low locomotor activity are the main factors. The particular effects of the different factors have been elucidated in special experiments. The locomotor activity of broilers with different growth rates has been observed in deep litter compartments with videotracking technique. The effects of locomotor activity were analysed through a training on treadmills in slow and fast growing broilers. Fast growing broilers showed a lower activity level from week one onwards and there was a pronounced drop in walking distances in the third week of age (21 to 8 meters per hour), while the slow growing broilers maintained a high activity level from 36 m throughout the fattening period. Systematic training of fast growing birds on treadmills increased the locomotion ability, the bone density and thickness and reduced the bending and twisting in leg bones. Increasing the distance between feeders and drinkers may be a method to increase locomotor activity under practical conditions and may be a method to reduce the incidence of leg disorders. Based on the results of previous experiments, a final test was carried out placing the feeder and drinker at two varied distances apart from each other (2 and 12 meters) and monitoring the effects on growth rate, locomotor activity, bone development and leg weakness in broilers. A total of 4800 male and female broilers (in groups of 600) were tested under virtually real conditions. The larger distance between food and water led to a three times increased level of locomotor activity. Weight development and food utilisation were not negatively influenced. Groups of birds, whose food and water supply were placed 12 metres apart, had significantly less cases of leg weakness and deaths due to leg disorders (2%). Increased walking activated the bone building processes of the tibia. This method is a practical way for broiler farmers to decrease leg weakness.