There are two main types of harnessing systems: yokes and collars. Collars are the most efficient for cattle, horses and donkeys, but are inappropriate for developing countries because of their complexity and cost. Yokes are therefore commonly used. However, in sub-Saharan Africa, where there has not been a long tradition of their use, lack of expertise ad appropriate harnesses often leads to problem of injury to animals and lack of control over them. In sub-Saharan Africa, humped cattle, such as zebu, tend to be yoked with withers yokes, whilst for non-humped cattle such as N'dama, neck yokes are used most often. However, the type of yoke used is less important than its quality, weight and proper use. In cooperation with the Cameroonian animal and veterinary research institute, CIRAD-SAR has developed an 'improved' double yoke and the 'ATECam' single-ox yoke. In trials of both of these yokes power output was improved. Their low cost makes them suitable for manufacture in developing countries.