Potential lignocellulose resources and their utilization by ruminants in tropical regions

The nature and estimated quantities of potential lignocellulose resources in tropical regions are described. The most abundant sources of these materials are the natural grasslands, crop residues and by-products, e.g. sugar cane, cereals and fruits, and, to a limited extent, cultivated grasses, e.g. guinea and elephant grass. The availability of these resources to livestock is limited by a variety of environmental and logistic factors, e.g. seasonality of production and problems of collection and transport. Additionally, the nutritive value of pastures and fodders in the tropics is relatively lower than in temperate regions owing to their higher fibre and lower N and P content, with consequent lowering of intake and digestibility. Crop residues also have low N and high lignin contents and are generally deficient in fermentable energy, fermentable N, protein and micronutrients. The possibilities for improving the nutritive value of tropical feeds are discussed; these include supplementation with urea, molasses and minerals, good quality forage, and/or ''by-pass'' nutrients, e.g. oil cakes, and treatment by various physical, chemical or biological methods. (author)