Towards Sustainable Ruminant Livestock Production in The Tropics Opportunities and Limitations of Rice Straw Based Systems

Abstract

Ruminants serve a multiple of purposes in South-East Asian farming systems. In addition to the production of meat and milk, livestock provide essential farm inputs, such as manure and draught. In part, niminant livestock production is based on low-quality residues from primary crop production. These materials can be converted into human consumable food, provided suitable supplements are
available. From a fanning system's perspective, the nutritive value derived from rice straw is discussed. Voluntary intake and digestibility of rice straw, i. e. nutritive value, varies between cultivars, independent of grain yield. In sheep, the nutrients derived from straw can be doubled through selection by offering excess straw. Moreover, individual animals show variation in voluntary intake, digestibility and
performance. Livestock performance relies heavily on supplements. Particularly with basal feeds not sufficient for maintenance needs, e.g. untreated straw, the conversion of supplement into gain increases with level of supplementation. At system level this means that the output is optimized by restricting the number of animals. In the dry season with limited amounts of supplement available, it is a
useful strategy to impose feed quality restriction. During the subsequent wet season the animals compensate through increased feed intake and a more efficient conversion of nutrients. It is concluded that in mixed crop-livestock production
systems largely geared towards the production of food crops, there are ample opportunities to attain moderate levels of ruminant livestock production.
However, from a system's point of view, it is perhaps not the primary question how rice straw could be fiilly utilized for production, but how and to what extent the utilization of rice straw is optimized taking into account the total package of
available feed resources.