ABSTRACT
Summary Cereal straw is an untapped carbohydrate source for ruminant animal feeds, but little information is available on genotypic differences in the feeding value of barleys (Hordeum vulgare L.) commonly grown in the northern Great Plains of the U.S.A. Our objective was to determine if barley genotypes differ in straw forage quality and if straw-quality parameters are associated with agronomic characters. Straw from 37 and 31 barley genotypes was sampled in 1977 and 1978, respectively. Straw from 10 barley genotypes grown at four locations was sampled in 1979. Standard laboratory procedures were used to determine the quality parameters measured. Correlations among straw-quality parameters and agronomic characters were determined in 1977 and 1978. Barley straw tested in 1977 and 1978 averaged 5.6% crude protein (CP), 42.0% in-vitro dry-matter disappearance (IVDMD), 50.7% acid detergent fiber (ADF), 71.8% neutral detergent fiber (NDF), 6.6% acid detergent lignin (ADL), 21.1% hemicellulose, 11.4% ash, 0.13% phosphorus (P), 0.58% calcium (Ca), and 0.20% magnesium (Mg). The average feeding value was different among environments with higher-quality straw produced in low-grain-yield environments. Significant differences among barley genotypes were found for most straw-quality parameters measured. Six-rowed barley straw was generally lower in forage quality than 2-rowed barley straw. Straw from Karl barley, a low-grain protein cultivar, was higher in CP and digestibility and lower in ADF and NDF than most genotypes. Significant genotype x environment interactions were detected for most straw-quality parameters except CP. Heading date and plant height correlations with straw-quality components varied among years. Grain, straw, and protein yields; lodging; and grain-protein percentage were not consistently correlated with a straw-quality component. We have demonstrated potentially useful differences in straw-forage quality among barley genotypes. The data suggest that genotypes high in straw quality can be selected without loss of desirable agronomic characters.
