The Role of Food Legume Straw and Stubble in Feeding Livestock

Abstract

The six million tonnes of food legume straws available in North Africa and West Asia can supply only 1% of the feed requirements of the ruminant livestock in these areas, compared with cereal straws which supply 30%. On a local or seasonal basis, however, food legume straw can be important, and an example is the use of lentil straw in the feeding of sheep during winter in Syria. Compared with barley and wheat straw, food legume straws contain more crude protein. Lentil and faba bean straws generally have higher metabolizable energy values than cereal straws but chickpea and pea straws often have lower values. Natural variation has been shown to exist in chickpea, lentil and faba bean straws. Straw from spring-sown chickpeas had a higher digestibility and crude protein content than that from winter-sown chickpeas but differences between chickpea varieties were not significant. Lentil varieties differed in the percentages of leaf, pod wall, branch and root material found in the straw. The digestibility of these plant fractions was in the order leaf>pod wall>branch>root. Variation in digestibility within fractions was considerable, particularly for pod walls. Biological methods, including nylon bag techniques, should be used in addition to conventional laboratory analyses to evaluate food legume straws. Where possible feeding experiments and animal production trials should be used in the evaluation process. Additional analyses for phenolic compounds, particularly phenolic acids esterified to cells walls, lignin and tannins may help to explain variation in straw quality and assist interpretation of animal-based investigations.