Genetic Variation in Acid Detergent Fiber, Neutral Detergent Fiber, Hemicellulose, Crude Protein, and Their Relationship with In Vitro Dry Matter Digestibility in Tall Fescue1

Abstract

Breeding for improved forage quality in tall fescue (Festuca arundinaceae, Schreb.) has received scant attention. The aim of this study was to generate information on genetic variability and how it varies with seasons, years, locations, and planting arrangements for acid detergent fiber (ADF), neutral detergent fiber (NDF), hemicellulose (HCL), and crude protein (CP) and also on the relationships of these analytical components with in vitro dry matter digestibility (IVDMD) and to formulate a selection program for improvedigestibility in tall fescue. A combining ability ✕ environment analysis was made on data collected from spring, summer and fall harvests in 1977 and 1978, from six tall fescue parent clones and their 15 single‐cross hybrids which were planted in rows in Corvallis, Oreg. and in rows and swards in Columbia, Mo. General combining ability (GCA) predominated for all measured quality characteristics. Of the genotype‐environment interactions, only GCA ✕ harvest effects were important. The high coefficients of determination for hybrid progeny performance due to GCA (r2gca) and generally low parent‐progeny regressions suggest that GCA of the parents is a better predictor of hybrid progeny performance than actual parental performance. Acid detergent fiber is a more transmissable trait than NDF, IVDMD, HCL, or CP. Acid detergent fiber and NDF were well correlated with IVDMD while HCL and CP were not. The results indicate that a selection program based on progeny testing for GCA for low ADF in row plantings in one location for all harvest seasons over I or 2 years would efficiently and conveniently result in rapid indirect selection improvement for digestibility in tall fescue.