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Black oat (Avena strigosa)

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Description
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Common names 

Black oat, lopsided oat, bristle oat, sand oat, small oat [English]; avoine maigre, avoine rude [French]; aveia preta, aveia-estrigosa [Portuguese]; Rauhhafer, schwarzhafer [German]; ukonkaura [Finnish]; busthavre [Norwegian]; purrhavre [Danish, Swedish]

Description 

Black oat (Avena strigosa Schreb.) is an annual grass from temperate areas that is used mostly in South America for forage for its good nutritive value and productivity.

The following video (in Portuguese) presents black oat in Brazil and its favourable characteristics (Chini, 2014):

Morphology

Black oat is a tufted grass with an upright habit. It can grow to a height of 0.8-1.5 m, depending on growing conditions. It has a dense root system. Black oat is a leafy species. The leaf blades are linear, flat, rough and numerous. The inflorescence is a loose open panicle. The panicle is drooping and bears pendulous, pedicellated spikelets. The inferior lemma is awned, straight and black (hence the name black oat), 1.5-3 cm long, somewhat lopsided (hence the name lopsided oat). The fruit is a hairy caryopsis. Avena strigosa has morphological differences from the common oat (Avena sativa): it is leafier with side panicles (instead of equilateral), plump kernels (instead of narrow), and smaller seeds (Diederichsen, 2014aHusson et al., 2012). Though black oat is the common name of Avena strigosa in English and other languages (aveia-preta in Portuguese), it should be noted that some varieties of Avena sativa also produce black grain, notably in France where black varieties of Avena sativa are very popular and more common than white ones (Sem-Partners, 2014).

Utilisation

Black oat is a valuable forage crop. It has earlier growth and a shorter production cycle than ryegrass, a high DM productivity and a high nutritive value with a good protein content (Dial, 2014; Paris et al., 2012; Macari et al., 2006; Sobczak et al., 2005). Black oat is a valuable cover crop used both in summer and winter (Dial, 2014; Brust et al., 2012; Suttie et al., 2004). Black oat can be grown for forage only or for forage and grain (Fontaneli et al., 2012). Its dense root system is beneficial to soil texture (Husson et al., 2012). Black oat used to be cultivated in northern Scotland as human food (grain), and for animal feeding as pasture, hay or grain (Weibull et al., 2002), but is now cultivated mostly in South America (Diederichsen, 2014b). Black oat can be grown on waste water from which it removes nutrients and thus reduces organic load. It is also reported to extract Cd (heavy metal) from the soil (Eustaquio Junior et al., 2010; Uraguchi et al., 2006). Black oat is a diploid Avena species that has great potential for the maintenance of biodiversity among oats and for breeding programmes (Husson et al., 2012). 

Distribution 

Black oat is native to the Iberian Peninsula (Spain and Portugal). It was cultivated in marginal environments or was a tolerated weed in cultivated oats (Avena sativa L.) in many parts of Europe (Mordvinkina, 1936 cited by Diederichsen, 2014a). Black oat almost completely disappeared from cultivation in Europe but there are relicts in the Scottish Islands and Lithuania (Diederichsen, 2014a). Most black oat is now cultivated in South America. The total global area of harvested lopisded oat was about 5 million ha in 2008, with 3 million ha in Brazil (Diederichsen, 2014b). It is also cultivated in temperate areas of Argentina, Uruguay and Chile, and in the tropical high altitude areas of Bolivia, Ecuador and Peru as a winter cover crop. In North Vietnam, black oat has been assessed for its ability to provide fodder during cooler periods (Salgado et al., 2010). In the south-eastern United States, Hawaii and Arizona, black oat is used for forage pasture and as a cover crop (Dial, 2014).

Black oat is a fast-growing forage that can be harvested 6 weeks after sowing (Gold Steinberg et al., 2005). It can grow from sea level up to an altitude of 1000 m (Fontaneli et al., 2012). It does well in places where summer temperatures remain cool (Suttie et al., 2004). Some Brazilian cultivars are adapted to more tropical conditions (good grain filling under high temperatures), while others are one of the most important winter cover crop in southern areas of Brazil where winter climatic conditions limit the growth of tropical forages (Rio Grande do Sul, Parana) (Silva et al., 2006). With Italian ryegrass (Lolium multiflorum), black oat is the most utilized temperate species in the cool season (Sobczak et al., 2005). Black oat does not survive below -8°C. It is tolerant of drought. It can grow on relatively infertile soils provided they are sufficiently drained (sandy or loamy soils, heavy clay with low nutrient value) (Fontaneli et al., 2012). Some cultivars have a high tolerance to Al in the soil (Crestani et al., 2009). Black oat prefers full sunlight but can grow in association with forage legumes. It has an outstanding resistance to rust (Puccinia graminis) (Gold Steinberg et al., 2005).

Forage management 

Establishment and associations

Black oat can be sown alone or in combination with grasses such as Italian ryegrass (Lolium multiflorum) and elephant grass (Pennisetum purpureum), or legumes such as berseem (Trifolium alexandrinum), stylo (Stylosanthes spp.), pinto peanut (Arachis pintoi) or vetch (Lathyrus or Vicia spp.) (Paris et al., 2012; Uhlein et al., 2008). In Brazil, Avena strigosa is generally cultivated in pure stands or associated with Italian ryegrass or legumes, and used as pasture. Black oat and elephant grass can be associated in a pasture because growth of the black oat is higher in the winter period whereas elephant grass grows more in summer (Sobczak et al., 2005).

Yield

Black oat yields about 3-8 t DM/ha (Salgado et al., 2013; Salgado et al., 2010; Cabral et al., 2010; Eustaquio Junior et al., 2010; Suttie et al., 2004).

Pasture and cut-and-carry

Black oat can be grazed or cut and then chopped and stall-fed (fresh) (Salgado et al., 2013). Moderate grazing should be done to improve forage production and animal performance. Black oat can be grazed rotationally during short periods (1-3 days) by high producing animals, which are then kept out for 30 days before re-entering the sward. Under such a system, black oat should not be grazed or cut below 7 cm in height. Under continuous grazing, stocking rate should be adapted to plant growth so that the stubble is comprised between 20 and 40 cm (Fontaneli et al., 2012).

Hay and silage

Black oat may be cut at the vegetative stage and dried to make hay or silage. Prior wilting is recommended for silage production due to its high moisture content, low soluble carbohydrates and high buffering power that prevents a reduction in pH. The use of bacteria such as Lactobacillus acidophilus and/or enzymes may improve silage quality (Berto et al., 1997).

Environmental impact 

Cover crop

Black oat is a valuable winter cover crop in places where frost does not occur. It tillers readily, providing good soil coverage. Black oat produces more mineral N than other cover crops such as rye (Schomberg et al., 2005). Black oat has a good C:N ratio that is favourable for soil N management (Dial, 2014). Black oat is efficient at translocating soil phosphorus in oxisol soils (Antony, 2007). In the northern part of Parana (Brazil), planting black oat as a winter cover crop resulted in increased soybean yield (+ 38%) and increased bean yield (+ 68%) (Derpsch et al., 1985 cited by Machado, 2000).

Weed control

Black oat prevents the development of broadleaf weeds. In the USA, it controlled 34% of weeds while other cover crops, such as rye, only controlled 26%, and wheat 19% in cotton grown under conservation tillage (USDA, 2005). Though it has been reported as having some allelopathic effects on cottonseed, the use of black oat as a cover crop had a better residual effect than rye on a following cottonseed crop (Bauer et al., 1999).

Nematode control

Black oat is reported to have nematicidal effect. As a cover crop, black oat was shown to be resistant to or inhibit root-knot nematodes (Lima et al., 2009). The use of black oat as a fallow crop before strawberry cultivation reduced nematode lesions more efficiently than sorghum (Sudan grass) or common oats (Dial, 2014). Some breeding programmes aim at selecting nematode suppressing black oats (Diederichsen, 2014a).

Phytoremediation

In Japan, black oat was reported to have good potential for cadmium extraction from agricultural soils (Uraguchi et al., 2006).

Nutritional aspects
Nutritional attributes 

Black oat forage is a nutritive grass, with a protein content ranging from 13% up to more than 26% DM. In a Brazilian study, the protein content was a quadratic function of N fertilization and reached 25% DM with 220 kg N per ha (Restelatto et al., 2014).

Ruminants 

Black oat is a valuable forage for ruminants with a good nutritive value.

Forage

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., 1998Dias 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., 1998Dias et al., 2011).

Dairy cattle

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). 

Growing cattle

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:

Animal Experiment Concentrate level Results Reference
Marchangus calves
(200 kg)
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
(180 kg)
Black oat/Italian ryegrass pasture fertilized with 0, 150 or 300 kg N/ha no supplement 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) no supplement 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 supplement No effect on DWG (1.21 to 1.41 kg/d) Canto et al., 1997
Crossbred steers
(312 kg)
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  32% concentrate  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

Goats

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).

Pigs 

No information found (2015).

Poultry 

No information found (2015).

Rabbits 

At the time of writing (December 2014), no literature about the use of black oat in rabbit feeding seemed available. Wild rabbits (Oryctolagus cuniculus) are reported to consume experimental seedlings of lopsided oat (Scholten et al., 2011). Since black oat is a good fodder for other domestic animals, it suggests that it could be used in rabbit feeding in the same way as common oat forage, taking into account the slight differences in chemical composition between the two species.

Nutritional tables
Tables of chemical composition and nutritional value 

Avg: average or predicted value; SD: standard deviation; Min: minimum value; Max: maximum value; Nb: number of values (samples) used

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 16.0 2.9 12.1 18.6 4  
Crude protein % DM 17.6 3.5 12.5 26.3 16  
Crude fibre % DM 30.6         *
NDF % DM 55.1 5.3 45.2 63.0 16  
ADF % DM 33.0 8.0 21.5 46.3 15  
Lignin % DM 3.6 0.8 2.6 4.5 6  
Ether extract % DM 2.0       1  
Ash % DM 9.6 1.9 7.6 11.3 3  
Gross energy MJ/kg DM 18.2         *
               
Ruminant nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 69.2         *
Energy digestibility, ruminants % 66.1         *
DE ruminants MJ/kg DM 12.1         *
ME ruminants MJ/kg DM 9.6         *
a (N) % 41.9 9.7 31.3 50.4 3  
b (N) % 54.9 9.0 46.4 64.4 3  
c (N) h-1 0.064 0.029 0.039 0.096 3  
Nitrogen degradability (effective, k=4%) % 76         *
Nitrogen degradability (effective, k=6%) % 70   69 77 2 *

The asterisk * indicates that the average value was obtained by an equation.

References

Berto et al., 1997; Kozloski et al., 2008; Luczyszyn et al., 2007; Moreira et al., 2007; Pires et al., 2006; Prado et al., 2004; Rossi Junior et al., 2013; Salgado et al., 2013

Last updated on 03/02/2015 16:07:07

References
References 
Datasheet citation 

Heuzé V., Tran G., Hassoun P., Lebas F., 2015. Black oat (Avena strigosa). Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. http://www.feedipedia.org/node/581 Last updated on October 26, 2015, 17:48

English correction by Tim Smith (Animal Science consultant) and Hélène Thiollet (AFZ)
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