E.J. Stevens, K.W. Armstrong, H.J. Bezar, W.B. Griffin and J.G. Hampton
SUMMARY
Oats remain an important crop in marginal ecologies, for grain as well as for fodder, bedding, hay, silage and livestock grain feed. They are spring or autumn-sown according to climate, and tolerate acid soils. Much of the crop, both grain and forage, is consumed on-farm. Hexaploid forms, Avena sativa and A. byzantina, are the commonest source of improved cultivars, but A. strigosa has become important in South America. Fodder cultivars are usually a by-product of breeding for grain. There are strong genotype × cultivar reactions, and careful screening of introductions is essential. Fodder oats have immense promise in the Himalaya-Hindu Kush region, and collaboration between countries for introduction and screening of material is highly desirable. The formation of a subregional fodder oat network is recommended.
Oats rank around sixth in world cereal production statistics, following wheat, maize, rice, barley and sorghum. Oat grain has always been an important form of livestock feed, and provides a good source of protein, fibre and minerals, but world oat grain production declined as farm mechanization increased between 1930 and 1950. Oats remain an important grain crop for people in marginal ecologies throughout the developing world, and for specialist uses in developed economies. In many parts of the world, oats are grown for use as grain as well as for forage and fodder, straw for bedding, hay, haylage, silage and chaff. Livestock grain feed is still the primary use of oat crops, accounting for an average of around 74 percent of the world’s total usage in 1991 to 1992 (Welch, 1995).
Oats are well adapted to a wide range of soil types and on acid soils can perform better than other small-grain cereals. Oats are mostly grown in cool moist climates and they can be sensitive to hot, dry weather between head emergence and maturity. For these reasons, world oat production is generally concentrated between latitudes 35-65°N, including Finland and Norway, and 20-46°S. Most of the world’s production comes from spring-sown cultivars, but autumn sowing is practised in higher-altitude regions, including the Himalaya-Hindu Kush range, and in regions where summers are hot and dry. Where winters are severe, such as in Canada, Scandinavia and northern United States of America (USA), and higher-altitude regions in the tropics, short- to medium-season maturing oat cultivars are generally sown. In regions with temperate climates, oats are variously spring, winter or autumn sown, depending on regional climatic conditions, crop rotation requirements, end use and other farming practices. In warmer regions, spring-type oats are sown in autumn to avoid summer heat and drought.
Canada, Germany, Poland, the Russian Federation, the countries of the former Soviet Union, and USA account for about 75 percent of the world’s supply of grain, seed and industrial grade oats. Since the 1960s, the proportion of oats used for feed has declined in the USA and Canada; remained unchanged in the former Soviet Union countries and Poland; and increased slightly in Germany. Oats used as feed in the USA are becoming a specialty equestrian feed for racehorses, hobby farmers and breeding stock. The leading exporters of oat grain are Argentina, Australia, Canada, Finland and Sweden. The European Union, Japan, the former Soviet Union, Switzerland and USA are the principal importers of oat grain.
A significant proportion of the oat grain and forages produced on smaller, more remote farms around the world, including the Himalayan region, are consumed on-farm and never enter the commercial market place. A case study from Nepal (Stevens et al., 2000), covering oats in the period dating back to the 1950s, shows how people in Afghanistan, China and Pakistan could benefit substantially from access to better cultivars to alleviate poverty and improve human and animal nutrition. These examples highlight the need for a coordinated international fodder oat network targeting resource-poor environments in relatively remote communities.
Oats are grown for grain, forage, fodder, straw, bedding, hay, haylage, silage and chaff. Food uses include oatmeal, oat flour, oat bran and oat flakes. Oats are one of the most nutritious cereals, high in protein and fibre. The protein of rolled oats is generally greater than that of other cereals. Many of the vitamins and minerals in oats are in the bran and germ, and most oat food products use the entire groat.
The exact origin of the oat is unclear. Oat (Avena sativa) seeds have been found in 4 000-year-old remains in Egypt. Oats may have spread there as a weed in wheat and barley as oat cultivation began much later than that of wheat and barley. Oats descended from a number of diploid (14 chromosomes) and tetraploid wild species. These grew mainly in the countries around the Mediterranean Sea, whereas the primitive wheats were grown mainly in southwest Asia. Oats were grown for grain in western Europe and mention was made of a red oat grown for fodder around Asia Minor.
The European white or yellow-hulled oat is thought to be the progenitor of the common oat, A. sativa. It spread to all parts of the world where moist cool conditions prevail, and was used as a springsown crop for food and feed grains. The wild red oat, A. sterilis, is thought to have been the progenitor of the cultivated red oat, A. byzantina. This species spread to the regions where temperature extremes occur frequently, such as the Mediterranean, southern states of USA, Africa, South America and Australia, and was used mainly for forage production. The A. byzantina species generally has greater heat, drought and cold tolerance. Both species are hexaploids with 42 chromosomes (6n=42).
The European white oat or yellow-hulled oat, A. sativa, and the cultivated red oat, A. byzantina, are self pollinating hexaploids and compatible with hybridizing techniques. In recent times, plant breeders have hybridized these species to select mainly grain- and food-type cultivars that are adapted to a wider range of climatic conditions. Most plant breeding investment has been and still is directed toward the improvement of grain production for food uses, where white grain types are generally preferred. Consequently, the colour of grain of both species is becoming more like that of A. sativa and less like that of A. byzantina. According to Coffman (1977), in Argentina, where A. byzantina was formerly the most popular species, A. sativa types now predominate. In the USA, most of the spring oats are A. sativa whereas the winter oats in the southeast and southwest originated as A. byzantina. Through the development of improved cultivars, A. byzantina has become more like A. sativa in appearance.
Modern plant breeding and oat development focuses primarily on oats grown for grain, not fodder. This development and investment bias toward grain cultivars continues, with a few exceptions, resulting in very few specific global references in the literature to fodder oats. There are major monographs (Webster, 1986; Marshall and Sorrells, 1992; Welch, 1995) on grain oats, but there are few literature sources useful for fodder oat improvement, even though fodder oats are used as a multipurpose crop worldwide. They are usually autumn sown, grazed prior to stem elongation and taken to maturity for use as feed or milling grains. Traditional oats (A. sativa) are used as forage throughout the world.
A diploid oat (A. strigosa) is also grown in South America as a forage crop. Sullivan, Hales and Norton (1982) compared a diploid oat with a triticale forage for fattening cattle. Although the diploid oat had a lower nutritive value, the oat yielded more forage per unit area than did triticale.
Research reviewed by Burgess, Grant and Nickolson (1972) found that the nutritive value of oat forage is high and with dry matter digestibilities in excess of 75 percent when fed to dairy cattle. Cuddeford (1995) suggests cereal straws have similar chemical compositions but oat straw has more digestible organic matter. He suggests that straw from spring oats has a higher metabolizable energy content than winter oats, and that both are better than the other cereals in terms of available energy. Oat straw is softer and more acceptable to livestock than are other cereal straws.
Despite the extensive worldwide use of oats for forage and fodder, very little of the world’s plant improvement research resources are devoted to the development of oats specifically for fodder uses; consequently, little detailed research data is available for review.
Breeding and selecting for both seedling and adult disease resistance - crown rust in particular - is an important part of oat improvement programmes in many of the world’s oat grain producing areas. In Brazil, where oat crops are widely grown for forage, there are serious problem with crown rust, and a similar situation exists in Queensland, Australia, and in New Zealand, where the increasing production of oat forage has increased the incidence of crown and stem rust in oat crops. Therefore, it is not surprising that cultivars selected for grain, in environments where plant diseases are potential yield limiting factors, have often fulfilled the requirements for improvements in forage yields. Many of the plant traits required for successful crop production apply to both forage and grain outcomes.
All cultivars in New Zealand and Australia are spring types, although some have a degree of winter cold tolerance. "Winter oats", not to be confused with "winter hardiness", is frequently used in a generic sense, such as for spring oats planted in the winter. Winter-hardy oats may have a place in the higher, cooler reaches of the Himalayan ranges, but it could be difficult to identify winter-hardy types specifically for the Temperate Asia Pasture and Fodder Working Group testing network. Breeding and selecting for improved winter hardiness is difficult. The trait is genetically complex and field selection is difficult in most environments as it is either too warm or excessively cold for effective selection.
Laboratory methods can be used, but these are expensive and imprecise. Despite these difficulties, progress, intentional or otherwise, has been made in developing oat germplasm with greater winter hardiness. Marshall (1992), in his review of winter hardiness, demonstrated that the area of winter oat adaptation in the USA showed a northward movement between the 1920s and 1960s due to the development of cultivars with improved winter hardiness.
In the Himalayan region, it is important that oats be screened for cool tolerance by sowing at high altitudes, using susceptible and known winter-hardy cultivars as controls, and using vegetative survival as the criterion for selection. In the early stages of a plant improvement programme, assessing germplasm for parental uses is crucial to success. Several countries, or their institutes, including individual plant breeders, maintain germplasm collections. Wesenberg, Briggle and Smith (1992) estimate that there are at least 22 significant Avena collections in the world, containing around 37 000 accessions, compared with 37 significant wheat collections, with 401 500 accessions, and 51 barley collections, with 212 000 accessions. A list of Avena germplasm base collections was published in Oat Science and Technology (1992: 799-803). The National Small Grains Collection of the United States Department of Agriculture Agriculture Research Service (USDA-ARS NSGC) is a collection comprising more than 113 000 accessions of wheat, barley, oats, rice, rye and triticale, and a comprehensive collection of wild and other cultivated species. It is maintained at several sites.
The NSGC germplasm is relatively easily available, through the internet or by mail. However, this material, unless its field performance is already known, is best screened within established programmes. Obtaining and evaluating germplasm can be a costly business, and is best done, in the first instance, within established programmes. Cultivar development involves the selection of parents, hybridization among parents, inbreeding, and selection among the resulting progeny, followed by replicated testing for yield and other important quantitative traits, with a final stage of multiplication, maintenance and distribution of seed.
The cultivar improvement objectives will reflect producers’ needs in the target environmental region, and the end uses of the crop, as grain, straw or fodder. Successful plant improvement programmes are difficult and expensive to replicate in the short term. Therefore, successful networking among the Himalayan communities, site controllers and researchers is the obvious recipe for the Temperate Asia Pasture and Fodder Network to accomplish its mission successfully.
Traditionally, discarded oat cultivars developed for grain production have been, and still are being, used as forage and fodder worldwide. Screening for forage and fodder production has used grain types that may not have met the target grain yields, but nevertheless have potential forage capability, so consequently they are streamed for potential forage uses by researchers whose primary focus is on improving grain yield. For example, dual-purpose cultivars selected for New Zealand from Canadian and European stocks were used up until the late 1980s, when the first cultivar (Charisma) selected purely for forage was released by Crop and Food Research (CFR). Until then, Mapua 70, a reselection from Makuru, developed from UK cultivar Milford, was the major forage and milling oat in New Zealand. A discarded grain cultivar (Lordship) from the New Zealand oat programme was released in Australia as a forage oat, although it is currently used for hay. An unreleased CFR cultivar with good grain yield is a potential candidate for release as a forage oat in New Zealand. It has also performed well in forage trials in the USA west of the Rocky Mountains and is included in lines from New Zealand to be tested in the Himalayas.
According to Stevens et al. (2000), oat cultivars from Canada, Europe and New Zealand, introduced into Asia over the past 20 years, continue to play a highly significant and strategically important role in feeding livestock across a wide range of ecologies, especially within the poorer regions of countries bordering the Himalayas, where they are used as green feed or oaten hay.
Considerable genotype by environment interaction has been noted across latitude, altitude and seasonal sequences, with some cultivars producing significantly better than others in some regions and under certain management regimes. Cultivars bred more recently, and previously- discarded populations, have never been tested systematically in these areas. However, if such populations or cultivars can be properly introduced and systematically evaluated and tested, there will remain the need for reliable maintainance and seed production and distribution.
Fodder oats have since the 1950s and 1960s grown to become a major forage and fodder crop along the Himalaya-Hindu Kush (HHK) zone, from Afghanistan to Myanmar. Increasingly, cereal fodders are being used to encourage and facilitate zero and tethered grazing. The HHK range is characterized by steep topography and climatic extremes, including very cold and prolonged winters at higher altitudes, variable soil types, and lack of irrigation in dry regions limiting the choice of agricultural activities. Crop production is limited to below circa 3 000 m above sea level.
Animal rearing is an important occupation in this region, at all altitudes. Above 3 000 m, overgrazing is a major problem and in some areas it has resulted in the destruction of the natural vegetation and forest cover. Alternative fodder sources are needed, particularly those that encourage and can sustain a shift from free grazing to zero grazing-tethered grazing, and to cut-and-carry systems. The fodder sources should be linked with a shift from lower value animals, such as cattle, sheep and goats, to buffalo. Buffalo can provide milk, meat and useful draught power. Remedial action is underway in a few areas, for example in Pakistan (Aga Khan Rural Support Programme) and Nepal, where it has become clear that widespread nationally coordinated attempts to resolve the ecological consequences of overgrazing will require a considerable improvement in the productive capability of land currently used for arable purposes. This will sustain the current animal population and provide measurable material benefits to the communities living in these higher altitude zones.
To achieve this, the range of oat cultivars available may need to be updated with winter-hardy types for use in the higher altitude zones. New cultivars are needed to extend the existing range of options at the higher altitude levels along the HKK. Cultivars with an improved yield capability that can be also grown at higher elevations than the current climatic limits for arable agriculture could relieve some of the overgrazing pressures and destruction of forest.
Fodder oats are used throughout the HHK region for grazing, feeding and bedding milking animals, young stock and draught animals. Some farmers use a cut-and-carry system, which is very effective in utilizing forage, by reducing waste normally associated with direct grazing. By using cut-and-carry systems, farmers have greater control over harvest timing and cutting height, and consequently over the vegetative recovery capability of the oat crop. The system also enables farmers to use overlapping cropping methods to provide a continuous supply of green feed for livestock.
Oats in general are more suited to cut-and-carry systems than to grazing, particularly in cold environments. Cereals, unlike pasture grasses, and oats in particular, have not been extensively bred for direct grazing, but, despite this, direct grazing of cereals, including oats, can work well in warmer regions.
As the available land currently used for food production becomes scarce in relation to increasing population, and the need for greater food production increases, more research is needed to develop special purpose forage cultivars that fit specific end uses. There are few oat breeding programmes where the primary objective is developing oats for forage, and very little work is underway to develop germplasm for conditions like the cool and high altitude regions found in the parts of the Himalayas.
A point at issue is to consider the potential for quantum leaps in oat cultivar performance were the oat crop a mandated food crop of an International Agriculture Research Centre, such as ICARDA or CIMMYT. It would provide potential spin-offs by providing the basis for smaller oat breeding operators to develop germplasm specifically for grain, forage and fodder uses, including lowering the temperature threshold at which oat germplasm can grow, and to produce higher yields of forage and fodder for livestock uses in cool regions, including the HHK region. Despite international funding issues, local crop improvement programmes have historically made the best possible use of whatever materials are locally available. These sources have been augmented by genetic material introduced from outside the region, bred in the overlapping ecologies of Europe, North America, Canada, Australia and New Zealand, and circulated via the Quaker International Oat Nursery (QION), FAO and a number of bilateral aid programmes.
Sadly, so far, there has been no coordinated international crop improvement programme for oats and fodder oats akin to the programmes for wheat, maize, rice and sorghum, for example. This leaves networks such as the Temperate Asia Pasture and Fodder Working Group having to look after their own needs. With the advent of plant variety protection, combined with a down turn in international aid, it has become increasingly difficult for smaller, less well endowed, developing countries along the HKK to obtain direct and to exchange germplasm, and otherwise to obtain access to, evaluate, develop, maintain and produce seed of improved, purpose-bred, fodder oats for stress-prone environments.
This has occurred at a time when, more than ever, improved cultivars of fodder oats are needed to help alleviate poverty, and to restore and manage the environment in sustainable ways that enhance local seed and food security. New, alternative networking approaches are needed, embodying the concepts introduced and discussed here.
The Himalayan region’s growers need access to modern cultivars without the imposition of the business and compliance- administration costs associated with plant variety protection and seed distribution schemes in the countries where these cultivars are developed. To find new germplasm and cultivars, the network should identify plant improvement groups willing to supply material and that are prepared to forgo seed royalties. This would mean substantial savings for the organizers, in a community-based evaluation system where plant variety protection and royalty collection are not village-based issues. The outcome would provide a rapid route to market for new cultivars. This would enable growers to take immediate advantage of new cultivars and technologies, free from all business compliance and cultivar ownership issues in the initial stages.
However, the mechanisms for the funding of crop improvement projects, inside existing programmes, will need to be investigated by international assistance agencies and national governments. Businesses sponsorships could be tried. Despite the problems associated with distributing modern oat cultivars, and plant variety protection and ownership issues, a wide range of oat germplasm for developing new populations is available to any network of plant breeders who respect the conventions of germplasm exchange and access. Released cultivars are usually maintained by the originating owner or their agent, and could be available for germplasm enhancement projects if not for commercial use.
The potential for an Oat Fodder Network as presented by Stevens et al. (2000) is generally accepted by oat research workers as the basis for moving forward to exploit the potential of the crop for the Himalayan region. Realistically, a structure such as an Oat Fodder Network is required to actively obtain and pre-screen material, prior to committing unknown material directly into a testing network. The Oat Fodder Network should also aim to develop a low cost preliminary screening system for a larger number of oat lines in the HHK region, from which selections can be made for entry into the more formalized testing system.
Hull-less (naked) oat is a variant of A. sativa, the cultivated hexaploid - a traditional grain and fodder oat, but without a hull. Naked oat cultivars offer farming families in this region a dual-purpose cropping option: fodder and an alternative human food source. Naked oats are hull-less grains, where the caryopsis (groat) separates from surrounding plant tissue during the threshing process. Hullless grains could be milled into flour by local householders. However, oat grains (hulled and hull-less) also have a higher oil content compared with other cereal grains, such as wheat, and consequently the shelf life for oat flour may be shorter than for wheat flour. Rancidity in damaged oat grains or milled flour can occur, affecting taste, but is not considered of any consequence for animal feeding. Several countries are developing naked oats for use as a food crop.
Diploid (A. strigosa) oat cultivars are another fodder crop option for use in the Himalayan region. More suited to forage production than grain production, a diploid cultivar in New Zealand field trials produced high yields of vegetative fodder in winter forage trials, from autumn sowing. Diploids are widely grown in South America for forage uses. The grain contains a husk, but naked varieties are available. No references for potential use as a food for milling into flour had been found at the time of writing. In a recent glasshouse experiment at CFR, the diploid cultivar was observed to produced a much larger root mass than traditional oat cultivars. This was not a controlled experiment for measuring root mass, but the differences between the diploid and a traditional hexaploid oat root mass on this occasion were large.
If diploid cultivars produce greater root mass under field conditions, diploids may have additional benefits in erosion control, in addition to fodder or hay uses. However, the authors emphasize that no research references had been identified to verify this observation.
