Animal husbandry is the mainstay of economy of resource poor farmers' in Eastern Indo-Gangetic Plains (EIGP). Average milk yield of indigenous cattle was recorded only 2.75+-0.66 kg/day compared to 7.55+-1.20 kg/day in improved cattle. Accordingly, milk yield was recorded to be 3.06+-0.86 and 5.12+-1.71 kg/day in indigenous and improved buffalo. Rearing of improved livestock resulted into 2-fold higher energy inputs compared to indigenous ones. However, energy output was highest through milk in case of indigenous as well as improved breeds of cattle and buffalo. Economic analysis revealed that cost of human labour was highest (GT 40 percent) for rearing of indigenous livestock, followed by dry fodder (GT 25 percent). In case of improved livestock, cost of concentrate feed had maximum input (GT 30 percent). On average, 2000 to 2100 square m of fodder area is required to feed one unit of improved livestock in EIGP. Net monetary benefit was highest for improved cattle (US Dollar 523.10), followed by improved buffalo (US Dollar 135.68). The data indicated that animal husbandry is an important food production system in EIGP besides food crops and both the systems have been found complimentary to one another through emphasis on resource recycling.