Effect of variety and level of inclusion of barley silage selected for varying neutral detergent fiber digestibility on ruminal fermentation and nutrient digestibility in feedlot heifers fed backgrounding and finishing diets

Two metabolism studies were conducted to evaluate the effect of variety and level of inclusion of barley silage on ruminal fermentation and total tract nutrient digestibility using beef heifers fed backgrounding (Study 1) and finishing (Study 2) diets. Both studies were 4 x 4 Latin square designs with a 2 x 2 factorial arrangement (barley varieties, CDC Cowboy and Xena; levels of inclusion, LOW and HIGH). Barley varieties did not vary in 30 h neutral detergent fiber (NDF) digestibility and averaged 37.1% +/- 1.86% (% of NDF) across varieties. Heifers fed CDC Cowboy had greater (P = 0.05) mean ruminal pH and a lower (P = 0.01) duration under pH 5.8 relative to those fed Xena in Study 1, whereas heifers fed HIGH-silage diets had lower (P = 0.05) duration under ruminal pH 5.8 than those fed LOW-silage diets in Study 2. Variety of barley had minimal impact on ruminal fermentation and total tract nutrient digestibility in heifers fed barley silage, although high NDF content decreased energy intake. High NDF barley varieties and greater inclusion levels also increased ruminal pH which may improve total tract fiber digestibility in heifers fed finishing diets.