The animal husbandry is regarded as a subsystem in the whole agro-ecosystem in this study. The conversion rates of energy,protein and nutrients by each kind of animals are analysed quantitatively. The commutations of energy and material between the animal subsystem and other subsystems and its environments are analysed, too. The productivity of Doudian village's animal husbandry and its role in the agro-ecosystem are evaluated objectively. Some suggestions on adjusting the composition of aimal colony are ma...