The OM digestibility of barley forage varies slightly according to the stage of maturity, and increases only from 61 to 65% between flowering and the dough stage (INRA, 2007). This corresponds both to a decrease in NDF digestibility and an increase in grain and starch content, which improves digestibility (Walsh et al., 2009). Comparable values are reported for silage: from 59% at the milk-dough stage (about 35% DM) (INRA, 2007) to 64-67% at 35-40% DM (Candlish et al., 1973). The OM digestibility of untreated straw averages 44-45% (Haddad, 2000; Madrid et al., 1997a; Phipps et al., 1990; Xandé, 1978; INRA, 2007). It can be slightly improved by treatment with ammonia: + 11 percentage points (INRA, 2007), urea (30-40 g urea/kg DM): + 6 to 8 points (Abate et al., 2009; Castrillo et al., 1995; Madrid et al., 1996), or NaOH (40 g/kg DM): + 14 percentage points (Phipps et al., 1990).
Barley forage used for silage can be harvested at heading, milk stage, or dough stage (i.e. between 27 and 49% DM, 40 to 60% grain; Kirchgessner et al., 1989; Wallsten et al., 2009). When harvested at late milk/early dough stage (35-40% DM), there is no advantage in adding acid (Candlish et al., 1973). The optimal harvest time is not critical because the quality of the forage decreases slowly with maturity, since DM intake and apparent digestibility tend to decrease when maturity increases, which impacts milk yield, milk protein and milk fat (Wallsten et al., 2009). At a similar stage (late-dough) for silage making, delaying the planting date (June vs. May) induces a higher in vitro NDF digestibility and protein content (Chow et al., 2008), but this does not affect intake and milk production in cows at mid to late lactation, whereas it tended to improve LW gain. Whole crop barley silage fed ad libitum as the sole feed is sufficient for dry or late lactating cows that consume less than 1.9% LW (Lund et al., 2006). Barley silage intake can be substantially increased to 2.5% of LW in dairy cows supplemented with concentrate at 1% LW in early or mid-lactation (Lund et al., 2006). Barley silage is comparable to pea or alfalfa silages for both intake and milk yield in dairy cows fed 50% forage diets in early lactation (Mustafa et al., 2000).
Barley silage is fed and digested similarly to maize or wheat silage by beef cattle (Walsh et al., 2008). Whole crop barley silage can be used by beef calves or rams supplemented with grain. In beef cattle, 15-20% silage is required to prevent digestive diseases with barley-based diets (Koenig et al., 2003), or barley + DDGS diets (wheat dried distillers grains with solubles) (Li et al., 2011). Spraying a commercial xylanase and cellulose on barley silage may slightly improve average daily gain and feed efficiency in feedlot cattle fed high, 80%, barley silage diets (McAllister et al., 1999).
The ingestibility of barley hay (2.5% LW, i.e. 65 g/kg LW0.75 in dry non-lactating adult ewes) is higher than that of vetch-oat hay (Chermiti, 1997). Barley hay supplemented with less than 50% concentrate can be used by ewes from 3 weeks before to 120 days after lambing (Awawdeh, 2011).
Barley can be used as straw. Untreated barley straw has a poor ingestibility (1,3% LW in castrated sheep) and requires progressive adaptation, which can be speeded up by nitrogen supplementation (Xandé, 1978). It should be fed with another forage (Haddad, 2000; Mir et al., 1988), grain (Ololade et al., 1975), or supplements. Supplementation of untreated straw with whey (Cetinkaya et al., 1997), urea and citrus by-products (Madrid et al., 1997b), or molasses (Gurdogan et al., 2000) was shown to increase intake, straw degradation and digestibility, weight gain and feed efficiency in goats (Madrid et al., 1997b; Cetinkaya et al., 1997) and sheep (Gurdogan et al., 2000).
Barley can be treated with urea (4-5% DM), ammonia (2-3% DM), and NaOH (4%) to improve intake, OM digestibility and performance. However, urea addition at 1% DM was poorly efficient (Haddad, 2000). Urea treatment was found more efficient than ammonia treatment (Kowalczyk, 1994). Urea-treated straw used alone was able to meet maintenance requirements for growing sheep, and allowed limited live-weight gain (Abate et al., 2009). Ammonia-treated straw was used for growing sheep at 1.9% LW without supplementation (Castrillo et al., 1995). It was also well ingested in lactating ewes (at 2.5% LW) when supplemented with concentrate (barley/citrus pulp mix) (Castrillo et al., 2004). Treatment of winter barley straw with NaOH greatly increased its digestibility, and improved forage intake and milk yield in dairy cows fed grass silage + barley straw diets (Phipps et al., 1990). In contrast with untreated straw, supplementation of urea-treated straw with alfalfa hay or vetch hay (Abate et al., 2009), or with dried lemon (Madrid et al., 1996), or the supplementation of urea + NaOH treated straw with citrus by-products (Madrid et al., 1998) did not improve the intake and digestibility of treated barley straw in sheep and goats, even slightly.