Black oat is a valuable forage for ruminants with a good nutritive value.
Digestibility and degradability
In Brazil, the in vitro digestibility of black oat forage varied between 76 and 81% (Restelatto et al., 2014), although a lower value of 64% was observed in Vietnam (Salgado et al., 2010). The latter study estimated the average ME value at 9.6 MJ/kg DM (Salgado et al., 2010). Black oat at 40 d of regrowth had a high protein content (26% DM) and the DM and fibrous fraction (NDF, ADF) were rapidly digested in the rumen (Pires et al., 2006). Black oat, grazed by sheep 60 d after sowing, had a lower potential DM degradability (70%) than Italian ryegrass (81%), which is mainly due to its lower NDF degradability (61%) compared to ryegrass (81%). However, the potential N degradability of black oat is as high (95%) as that of Italian ryegrass (96%) (Rossi Junior et al., 2013).
The DM and OM digestibility of black oat hay fed alone in limited amounts (1.5, 2.0, 2.5 % BW), or ad libitum, to 133-136 kg steers (Ospina et al., 1998; Dias et al., 2011) decreased from 57 and 61% to 47 and 60%, respectively (Dias et al., 2011). This represented a decrease of about 8.3 to 10.0 percentage points for every 1% of amount offered (Ospina et al., 1998; Dias et al., 2011).
In Vietnam, in dairy cows fed a basal diet of tropical forages plus concentrate, fresh black oat included at 35% of the forage DM did not alter forage intake, milk yield and composition, but the rate of decline in milk yield was lower with black oat than without (4-7% vs. 12-14%) (Salgado et al., 2013).
Beef cattle can graze black oat without supplementation, but adding a concentrate may result in better performance. All trials cited below have been conducted in Brazil on beef cattle.
Trials with pastures of Avena strigosa grazed by steers and heifers in Brazil:
|Black oat pasture grazed at two stocking rates with concentrates (C+) or without (C-)
||C+= 0.8% BW
||No effect of stocking rate on DWG (0.652 – 0.691 kg/d); higher DWG with C+ (0.749 kg/d) than C- (0.594 kg/d)
||Menezes et al., 2012
|Charolais and crossbreed with Nelore heifers (158 kg)
||Black oat compared to black oat/Italian ryegrass pasture both supplemented with concentrate
||C= 0.7% BW
||No effect on DWG (0.822 kg/d or 495 kg/ha)
||Macari et al., 2006
|Charolais - Nelore crossbred calves
|Black oat/Italian ryegrass pasture fertilized with 0, 150 or 300 kg N/ha
||No effect of added fertiliser on DWG (0.925 to 1.045 kg/d)
||Lupatini et al., 2013
|Nelore male calves (130-180 kg)
||Black oat and field pea mixed pasture offered at different herbage heights (9 to 18 cm)
||DWG increased from 0.497 to 1.017 kg/d with 9 and 18 cm height respectively
||Grise et al., 2002
|Nelore, Charolais and NxC steers
||Comparison of fertilized black oat, black oat/vetch, black oat/Italian ryegrass pastures
||No effect on DWG (1.21 to 1.41 kg/d)
||Canto et al., 1997
|Mature black oat forage treated with urea and mixed with concentrate
||40, 55 or 70% concentrate
||DM intake (6.8 to 8.1 kg DM/d) and DWG (0.608 to 0.947 kg/d) increased with increasing concentrate level
||Vargas Junior et al., 2002
|Canchin steers (378 kg)
||Black oat silage replaced 20 or 40% maize silage in a complete diet
|| No difference in DM intake (9.5 to 8.6 kg) or DWG (1.05 to 0.85 kg/d)
||Nostre et al., 1994
DWG: daily weight gain
In young growing Boer goats (21 kg BW) grazing black oat pasture, a concentrate supplement had a depressing effect on grazing time and pasture DM intake, which decreased from 2.4% (with 0% concentrate) to 1.1% of BW (with 1.5% concentrate). Daily live-weight gain was also reduced with concentrate (from 125 g/d to 90 g/d), but there was a positive effect on gain per ha (Adami et al., 2013). In Anglo-Nubian goats (28 kg) grazing pure stands of black oat or in combination with Italian ryegrass, grazing time and bite rate were higher for the pure stands (Bratti et al., 2009).
Black oat grain
In Charolais x Nelore steers, black oat grain totally replaced sorghum grain in fattening diets based on silage without any effects on carcass weight and quality (Faturi et al., 2002).