Nutritional evaluation of forage barley varieties for silage

Abstract

A lack of information about nutritional and digestibility characteristics of common barley varieties grown for silage in western Canada has resulted in producers selecting varieties more on yield and other agronomic characteristics as opposed to nutritional value. The overall objective of this research was to evaluate nutritional and 30-h NDF digestibility (NDFD30h) characteristics of common Canadian barley varieties, changes in NDFD30h characteristics of these varieties with advancing maturity and the effect of feeding these varieties on the performance of feedlot steers. A nutritional evaluation of commercial barley silage samples harvested at mid-dough stage indicated that CDC Cowboy had a greater (P < 0.01) NDFD30h relative to Legacy and Xena with CDC Copeland, Falcon and AC Metcalfe intermediate. However, in a subsequent trial, growing CDC Cowboy, CDC Copeland and Xena (high, intermediate and low NDFD30h respectively) and harvesting on the same day across varieties did not (P > 0.05) result in variability in NDFD30h. A feedlot and metabolism trial utilizing the 3 barley varieties at 2 (HIGH and LOW) levels of inclusion indicated that backgrounding steers fed CDC Cowboy and HIGH silage diets had lower (P < 0.01) DMI, ADG and end of backgrounding BW while steers fed HIGH silage finishing diets had compensatory gain relative to those fed LOW silage diets. Ruminal fermentation and total tract digestibility characteristics of heifers fed backgrounding and finishing diets were similar (P > 0.05) across treatments. When CDC Cowboy, CDC Copeland and Xena were seeded, treated and harvested from replicated plots at four stages of maturity (milk, early-, mid- and hard-dough) over 2 crop years, there was a variety × maturity interaction with CDC Cowboy having greater (P < 0.01) NDFD30h at early-dough than Xena and greater (P < 0.01) NDFD30h at hard-dough than CDC Copeland. As such, there is potential for producers to select barley varieties with enhanced nutritional and agronomic characteristics. Harvesting CDC cowboy at early-dough for silage for dairy and CDC Cowboy and Xena at hard-dough for swath grazing would likely improve the nutritive value of forage and could lead to specific maturity targets for different farm operations (beef vs. dairy).