In sheep fed diets containing ad libitum barley straw, body weight change is closely correlated with straw intake. We are finding that it is more effective to select genotypes for straw intake using calibrated indirect tests than by conducting intake trials with sheep. Not only are the tests cheaper, but the test results are more heritable, even when their genotypic correlation with intake is allowed for. Of the tests, Near Infrared Reflectance Spectroscopy is the most effective, followed by in sacco dry matter loss, acid detergent fibre, pair-preference tests in sheep, and in vitro gas production with rumen fluid.