The energy role of cattle in the Bangladesh agro-ecosystem

In energy cycling processes of ecosystems, the role of cattle is to convert agricultural by-products, which have inferior use for humans, into valuable products of human utility. Cattle utilize 60% of consumed energy for self-maintenance and growth. Adult female cows get more energy input because of their added contributions of milking, calving and draught purposes. The main source of energy for cattle is rice straw. Grazing facilities and fodder cultivation are practically absent. Weeds of crop fields and roadside grasses are the only sources of green grasses, which are seasonally available. Total consumption of feed seems to be inadequate. Of the total energy produced, 73% has immediate human utility as work, milk and dung (70% used as fuel). The other portion of the energy produced as calves and dung provide indirect contributions. The smaller portion of the dung used in fertilizing land is a capital investment in crop production. The gross energetic efficiency calculated on the basis of immediate human utility is 29%. This high efficiency of cattle is not due to the more productive performance but because of more scrupulous utilization of products by the rural population. The current system of energy cycling through cattle seems to be appropriate for supplying products of human utility in an ecological framework. (C) 1998 Elsevier Science B.V. All rights reserved.