Effect of variety and stage of maturity at harvest on nutrient and neutral detergent fiber digestibility of forage barley grown in western Canada

This study evaluated the effect of variety (V; CDC Cowboy, CDC Copeland, and Xena) and stage of harvest maturity (M; milk, early-, mid-, and hard-dough) on nutrient and neutral detergent fiber digestibility (NDFD) characteristics of barley forage using a randomized complete block design with 3 x 4 factorial treatment arrangement. Barley varieties had similar crude protein, but CDC Cowboy had greater (P < 0.01) acid detergent fiber (ADF), neutral detergent fiber (NDF), and lignin, and lower (P < 0.01) total digestible nutrient (TDN) content relative to Xena. Starch content of CDC Cowboy was lower (P < 0.01) than Xena at all stages of maturity with CDC Copeland intermediate at early-and mid-dough stages. Crude protein, ADF, NDF, and lignin content decreased (P < 0.01) while starch and TDN content increased (P < 0.01) with advancing maturity. Xena had greater (P < 0.01) NDFD, as determined by 6 h in vitro incubation using Daisy(II) system (NDFD6h), at milk, mid-and hard-dough stages of maturity than CDC Cowboy with CDC Copeland intermediate at mid-dough. However, CDC Cowboy had greater (P < 0.01) NDFD, as determined by 30 h in vitro incubation using DaisyII system (NDFD30h), at early-dough stage than Xena and greater NDFD30h at hard-dough stage than CDC Copeland. Xena had the lowest (P < 0.01) indigestible NDF based on 288 h ruminal in situ incubation (INDF288h), relative to CDC Copeland. These results indicate that to optimize NDFD30h, variety should be considered when deciding the timing of harvest.