Energy needs of the free-ranging goat

The new tendency in livestock production systems invites all people involved in ruminant management to pass from intensive to semi-extensive and extensive systems. To accomplish this goal a deep knowledge in several aspects of the animal behaviour and nutrition is needed. The availability of energy is the main limiting factor in animal production for an efficient utilization of resources and for the achievement of acceptable levels of animal performance compatible with resource preservation. This paper deals with the assessment of the energy requirements of goats with particular reference to the free-ranging animal. As a first step, a headline is dedicated to bring the digestion capacity to light with some very particular characteristics in goats. It makes reference to the energy requirements for maintenance and lactation. Attention is paid to the efficiency with which the animal utilizes the available energy of feeds in these processes. Data are given for the energy cost of the two main activities in grazing: eating and walking. Emphasis is placed on the estimation of total energy expenditure of goats in open range including methods (factorial and isotopic) and the information that, to our knowledge, has appeared in the literature. Applications of direct estimations seem a better approach than to use theoretical values to get energy expenditure in grazing animals. Further investigation is needed to develop and improve new and existing techniques to quantify the total energy expenditure of animals in grazing systems. (c) 2005 Elsevier B.V. All rights reserved.