Oats play an important role in human and livestock nutrition, and as such an understanding of the genetics of oats is significant in world agriculture and economics. Oats provides grain for humans and livestock, a grazing or forage crop for livestock, as well as the ability to provide combined grazing and grain production. While the significance of the oat grain in benefiting human health has received considerable attention in the past decade, relatively little attention has been given to this important attribute of combined grazing, grain production and total crop value in the research and extension literature. This reflects a lack of awareness of the full potential of the oat crop. Based on the recent findings of FAO studies, the world supply of agricultural produce is meeting the demands of the current world population. The total world production of cereals increased at an annual rate of 1.45% over the period of 1981-1990, while total meat production increased at an annual rate of 2.87%. These trends suggest that increased cereal crop yields have allowed for an increase in the area available for pasture and hence livestock production. Improving the total quantity and quality of world pasture production is therefore becoming increasingly important for meeting the corresponding increases in global food demands. The oat crop has a sigficant role to play in this increase in pasture production.
Introduction
The importance of the oat crop in human and animal nutrition has been established only relatively recently. Studies demonstrating the cholesterol lowering effect of oat bran and other oat products in laboratory animals and humans have been known since the early 1990s. This has been attributed to the high soluble fibre (β-glucan) content of oats and oaten bran, confirming traditional beliefs in the value of oats, relative to all other cereals. Knowledge of β-glucan, oil and protein contents of oat varieties, in various germplasm collections, will enable breeders to add value to all agronomically useful varieties for optimum human and animal nutrition.
The nutritional and health qualities of the oat crop are of considerable importance in establishing the context for this book and these attributes are discussed in this chapter. A brief introduction to oat genetics and the origin of the oat crop is also provided as well as a discussion of the broader agricultural and economic significance of this crop globally.
Oat grain quality and health
Overview
Research has identified oats as the health grain for humans and animals (McDonald et al. 1992). There are active components in oats which lower blood lipids, regulate blood glucose and protect against tumour development in the colon.
The cholesterol-lowering benefits of oats have been attributed to ß-glucan in the oat fibre fraction. Oat bran and oatmeal supplementation studies show a more favourable effect on blood glucose and insulin responses than other cereal grains like wheat and maize. Oat soluble fibre should delay the onset of fatigue and enhance athletic performance. Besides addressing major diseases of wealthy nations, like coronary heart disease, cancer and diabetes, oats could provide benefits for blood pressure and weight reduction.
Oats also contain a high proportion of monounsaturated fat, antioxidants such as tocotrienols, and an amino acid composition rich in arginine relative to lysine. Antioxidants have been linked to reduced risk of cancer, heart disease and degenerative changes in the eye as well as to increased immune function (Bunce et al. 1990; Diplock 1991).
Coeliac disease in human individuals, sensitive to gluten and unable to eat wheat, barley or rye (all high in gluten) can, usually, safely eat oats which contains only trace quantities of the gluten protein (Welsh, 1995).
Table 1.1 shows the marked superiority of oat bran over rolled oats both in protein and in dietary fibre, contrary to popular uninformed opinion which formerly regarded oat bran as less valuable.
Table 1.2 compares feed grain values of the 3 winter cereals and maize. It should be noted that high fibre in oats goes hand-in-hand with a high oil content. The oil composition in oats is high in linoleic acid and low in linolenic acid.
Oat hulls are very effective in inhibiting the development of dental caries in animals at dietary levels of 3 to 25%. Phenolic compounds in the hulls may involve antioxidant or antimicrobial activity (Madsen, 1981).
Table 1.1 Chemical composition of oatsa.
Nutrients |
Rolled Oats |
Oat Bran |
Energy |
1600 kJ |
1030kJ |
Protein |
10.5 |
17.3 |
Fat, total |
8.0 |
7.0 |
Fat, saturated |
1.5 |
1.2 |
Carbohydrates |
61 |
50.3 |
Sugars |
0.0 |
2.6 |
Dietary fibre |
10.0 |
15.9 |
Sodium |
< 5.0 |
< 5.0 |
Thiamine (B1) |
- |
1.2 mg |
a From BiLo (2004). Values given in grams per 100 grams.
Table 1.2 Comparative feed grain values of oats, barley, wheat and maizea.
Nutrients |
Oats |
Barley |
Wheat |
Maize |
Protein (%N x 6.25) |
10.5 |
11.0 |
12.5 |
10.4 |
Oil (%) |
5 |
2 |
2 |
4 |
Crude fibre (%) |
10 |
5 |
2 |
2 |
GEb (MJ/kg DMd) |
19.6 |
18.5 |
18.7 |
18.9 |
MEc (ruminants) |
12.0 |
12.9 |
13.5 |
13.8 |
a From Welsh (1986); bGE = Gross energy; cME = Metabolisable energy in ruminants; d = dry matter.
Genes encoding the oat kernel storage proteins, avenins and globulins, have been isolated and characterised. Oat globulins, which make up 50-80% of the kernel protein, resemble legume globulins in amino acid composition thus explaining the nutritionally balanced amino acid content of oat proteins. The protein of oats is unique among temperate cereals because of this high content of globulin, which closely resembles a major seed legume protein, glycinin (Peterson and Brinegar, 1986). Therefore oat and legume proteins may have similar hypocholesterolaemic properties. These properties or cholesterol reducing effects are higher in oat bran than in rolled oats. Thus, Ripsin et al. (1992) took 3g of soluble fibre to be equivalent to 42g of oat bran or 84g of oatmeal. This superior effect of oat bran suggests that there is a role for both the gum and the protein since both these components are higher in the bran. The major component of oat gum is β-glucan.
Oats have long been the breakfast cereal of the Celtic people of Ireland, Scotland, Wales and the cooler, wetter northern counties of England, the North American, Scandinavian, North European and Slavonic peoples. More recently, the crop has spread to West Africa and is likely to become universally important with its unique value for the health of humans and animals, relative to other grains.
Composition of oat grain
Oats have a slightly sweet, slightly sour taste, which does not require the addition of sugar or honey. Oats can also be blended with a variety of other health-giving foods. To understand the nutritional significance of oats, it is necessary to look at the various constituents of oats.
Protein. Oats have a higher concentration of well-balanced protein than other cereals and therefore a greater potential value to provide a substantial proportion of protein requirements than other cereals. Among the essential amino acids that make up protein quality, cereals are generally limiting in lysine. Oat protein is higher in lysine than that of other cereals.
Lipids. Lipids are a concentrated source of energy, being higher in energy value than carbohydrate. The lipid concentration of oats is higher than that of other cereals. The lipid composition of oats is favourable because of the high proportion of unsaturated fatty acids. Oats are high in linoleic acid, an essential fatty acid for human nutrition. Linoleic acid is used in the synthesis of prostaglandins that are found in all tissues and regulates smooth muscles.
Minerals. Oats are a good source of manganese (Mn), magnesium (Mg), iron (Fe), calcium (Ca), zinc (Zn) and copper (Cu). The major proportion (58%) of the phosphorus in the oat kernel occurs as phytic acid. Phytic acid may bind minerals, making them unavailable in nutrients. Rolled oats, however, did not decrease the absorption of Fe any more than did milk, which contains no phytic acid.
Vitamins. Oats contain little or no vitamin A, C or D but it does contain small yet significant quantities of thiamine, folic acid, biotin and pantothenic acid.
Starch. The starch concentration of oats on a whole grain basis is lower than that of rye, barley or wheat, reflecting the relatively thick hull of oats.
Soluble sugars. Total free sugar concentration of oats is low, relative to barley, wheat and rye, but similar to maize (Table 1.1).
Fibre. Dietary fibre is defined as plant polysaccharides and lignin, substances resistant to human digestive enzymes. Starch is the only plant polysaccharide that is digestible by humans. Therefore, dietary fibre includes all non-starchy polysaccharides (NSP) plus lignin.
NSP include cellulose, hemicellulose and lignin (all water insoluble), whereas other fibre components are classified as soluble. The solubility factor is important for understanding the importance of oats for human nutrition (Shinnick et al. 1988).
The significance of oat fibre and human health
Whole oats, before processing, have 20-37% fibre. After processing, the oatmeal has about 12% fibre, while the oat bran, the coarse milling fraction, contains about 18% dietary fibre.
The dietary fibre of oats is a mixture of soluble and insoluble fractions and the soluble fraction is high relative to other cereals due to the high concentration of ß-glucans in oats. The irregular configuration of these polymers makes them partially water soluble and functionally different from cellulose in the human digestive system. Only barley exceeds oats in concentration of ß-glucans, but a higher proportion of oat ß-glucan is soluble. There is a wide range of ß-glucan concentration among diploid oat species but narrower ranges among tetraploid and hexaploid oat species. The highest values are found in the hexaploid or cultivated species of oats.
Oat ß-glucans are especially abundant in the bran fraction that contains the outer layer of the caryopsis and thick cell walls of the sub-aleurone region (Henry 1987).
Cholesterol lowering properties
The cholesterol lowering properties (or hypocholesterolemic) effects of oats have been proven in both animal and human studies. These are discussed in the following sections.
Animal studies. As early as 1963, rolled oats were found to decrease serum cholesterol level of rats fed a semi purified diet with 10g per kg cholesterol and 2g per kg cholic acid (De Groot et al. 1963). The hypocholesterolemic effect of oats was greater than that of other grains tested. In other experiments, the soluble gum fraction of oat bran was the most effective in lowering serum and liver cholesterol.
Human studies. Studies with experimental animals have been confirmed in human feeding trials. When hypercholesterolemic male subjects were fed diets containing 140g of rolled oats daily, their cholesterol levels were significantly lowered 11% in 3 weeks, and levels rose again when the oat-containing diets were discontinued (De Groot et al. 1963). In another study, an 8% drop in the serum cholesterol levels of 17 hypercholesterolemic individuals was observed after 4 weeks of a diet containing <35% of energy from fat (Turnbull and Leeds 1987). Subsequently, the inclusion of 150g of rolled oats resulted in a further reduction of serum cholesterol levels by 5%, whereas wheat supplementation produced no further reduction in cholesterol. Further, in a study involving 236 subjects with normal cholesterol levels, total cholesterol decreased 6.6% with a fat-modified diet alone and 8.3% with a fat-modified diet plus 56g of oatmeal daily (Van Horn et al. 1988). This study showed that oatmeal or oat bran ingestion may enhance serum cholesterol reduction induced by dietary fat modification both in individuals with high cholesterol and healthy levels.
Hypotheses to explain cholesterol lowering by oats. There are several theories as to how oats lead to lowering of cholesterol.
The value of oat soluble fibre has been explained by dietary cholesterol absorption, bile acid reabsorption, production of lipoproteins in the liver and removal of lipoproteins in peripheral tissues (Anderson and Gustafson 1988).
The presence of oat products in the small intestine increases the viscosity of the intestinal contents, leading to a slower rate of dietary cholesterol absorption, thus reducing its availability and increasing faecal excretion (Lund et al. 1989). In the same study, oat bran diets increased the faecal excretion of bile acids in human subjects. Lower amounts of bile acids returned to the liver may divert liver cholesterol from lipoproteins to bile acids. However, not all soluble fibre sources that lower plasma cholesterol increase bile acid excretion as does oat bran fibre, and the magnitude of the increase from those that do, is small.
A further hypothesis is that oat fibre-induced short chain fatty acids inhibit cholesterol synthesis in peripheral tissues. This would result in a surplus of low-density lipoprotein (LDL) receptors, to increase the rate of LDL clearance. No single mechanism will explain the effects on cholesterol concentrations of oat bran soluble fibre (Marshall and Sorrells 1992).
Further, the effects of a high-fat meal (50g fat) on healthy individuals have been shown to be alleviated by oats. Endothelial dysfunction induced by acute fat ingestion is prevented by concomitant ingestion of oats or vitamin E, but not wheat. As a result, Katz et al. (2001) concluded that oats are better than wheat for cardiovascular health.
The glycemic effects of oats
Soluble dietary fibre in the diet slows the increase in blood glucose that normally follows a meal and is important in the treatment of Type II diabetes. Ingestion of oatmeal or oat bran decreased the glycemic index (blood glucose response relative to that induced by white bread) and insulin response in healthy and diabetic individuals (Heaton et al. 1988).
In no insulin-requiring diabetics, oat bran and oat gum at levels of 8g of soluble fibre slowed the rate of increase in blood glucose (Braaten et al. 1988). At 40 min, blood glucose concentrations were significantly lower for both treatments, compared to a control (cream of wheat), and peak glucose concentrations were delayed 30 to 40 min by both treatments. Similar results were obtained with healthy individuals. Oat gum was as effective as guar gum, but oat gum was tolerated better by most subjects. Oat bran with 15% ß-glucan lowered blood glucose by 40%.
Prevention of colon cancer
The antioxidant properties of the tocotrienols and phenolic compounds in oats should inhibit colon tumour development. In countries where the diet is associated with a low prevalence of coronary heart disease, prevalence of colon cancer is also low (McDonald et al. 1992).
Relevance of the oat health factors to agriculture
The oat health factors are also of significance to agriculture more broadly and these are discussed in the following sections.
Relevance to plant breeding. This book stresses the importance of dual-purpose oat breeding, that is, oats used for grazing and grain production (described in Chapters Two through to Six), for which the most successful centre for NSW was at Glen Innes. There is no longer a need to grow oats only for ease of milling. Heavily grazed oats may or may not (depending on good summer rain) recover grain with a higher proportion of oat bran, now the most sought after health component of the oat crop, both for humans and animals. Oat bran is of significance because it contains a high proportion of ß-glucan.
Composition analysis shows 4.3-4.6% ß-glucan in rolled oats and 7.3-8.9% in oat bran (Welch 1995). The lignin (insoluble fibre) component of total fibre in oat bran was 20% while that of oatmeal was 27%, indicating total lignin contents of 3.8% and 3.3% respectively (Shinnick et al. 1988). Within a given oat cultivar, increasing nitrogen fertility levels increased groat (i.e. seed minus the husk) protein and groat ß-glucan (Welch et al. 1991). There are also genotypic differences in groat ß-glucan and this can be selected for without undesirable correlated responses (Peterson 1991). In oats, the β-glucan is found within the bran (or the outer portion) of the groat.
Oats, belonging to the Aveneae family, have higher levels of all the essential amino acids, namely cysteine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, tyrosine and valine, than the Triticeae family, which includes wheat, rye and barley. Lysine tends to be the first limiting essential amino acid in cereals and lysine deficiency is exacerbated if the protein content of a cereal is increased by nitrogen fertilizer application. The decline in protein quality at higher protein levels is less pronounced in oats than in other cereals. This is associated with the relative contribution of the various protein solubility fractions to oat total protein. The prolamine fraction, which is low in essential amino acids, is chiefly increased in other cereals, as protein is raised by genetic or environmental changes. This accounts for the marked decline in protein quality observed in wheat, barley or maize as protein is increased (Mossé 1968). Globulin was found to be the major protein fraction in oats. Since the globulin fraction has a similar amino acid composition to the total protein, the relative increase in globulins with increasing total protein accounts for the relative stability of the amino acid composition of oats over a wide range of protein contents (Peterson 1976). Thus, globulins account for 70-80% of the total oat groat protein, with glutelins accounting for less than 5-10% of the total oat groat proteins.
Relevance to milk production. Friesian-cross cows were fed ad libitum on grain-based diets, comparing barley, wheat and oats, all rolled. Although the oat-based diet had the lowest content of dietary metabolisable energy (MJ/kg), it produced the greatest yield of milk and milk fat. Replacing barley with oats changed the fatty acid composition of the milk, by significantly reducing the saturated fatty acids and significantly increasing the content of stearic and oleic acids (Moran 1986). The oat-based diet in dairy cattle therefore increases the appeal of milk and milk products to the health-conscious consumer.
Relevance to animal feeding and production. Oats may be successfully fed to pigs, cattle, sheep, poultry and horses. By crushing oats and feeding them to pigs, the Author, farming at Temora from 1972 to 1985, obtained a price premium from Gilbertsons of Melbourne (meat processors), due to the reduction in back-fat, which was high when he was feeding crushed wheat to his pigs (both lots receiving a similar protein supplement). Oats in cow rations produced milk fat with an increased proportion of polyunsaturated fatty acids (Martin and Thomas 1988).
The high fibre content of whole oats limits their use to ruminants and horses, both capable of digesting fibre. Oats is the only cereal that does not need to be processed (as by rolling) prior to feeding to horses. For highly productive animals, naked oats have a superior nutrient content to wheat and barley and for this reason they justify a price premium on the basis of least-cost formulation (Valentine 1990).
Oats are the preferred grain for horses: other cereals, like wheat, pack too tightly in the gut, whereas oats remain in a loose mass that can be easily digested by the horse.
The two facets of the oat crop are (1) herbage that becomes richer in protein the more frequently it is grazed and (2) grain, which is the safest of the cereals for ruminants and farm work horses (Whittemore and Elsley, 1976). In varying proportions, any nutritive ratio such as 10:1 (starch:protein equivalent) for dry and resting stock or 4:1 (starch:protein equivalent) for breeders, lactators or growers, can be easily attained. Even oaten straw, which is nutritionally superior to that of wheat and barley, can be used for maintenance (Welch, 1986).
Oat straw is softer and more acceptable to stock than other cereal straws and has a higher metabolisable energy content than other cereals in terms of available energy. Oat pasture is superior to native grass-subterranean clover pasture for ewe live-weight gain (Dann et. al. 1974). For finishing prime lambs, daily live-weight gains of 400 g and stocking rates of 60 lambs per ha were reported on oat pastures (Archer and Swain 1977).
A Canadian study investigated growth performance, carcass and meat quality of pigs fed oat-based diets containing four levels of β-glucans. No evidence of detrimental effect of ß-glucans in oat-based diets, particularly at levels below 4%, was detected, lending support for the inclusion of oats in finisher diets (Fortin et al. 2003).
The high quality of oat grain and especially the biological value of its protein content and higher calcium content are both important for humans and young growing animals including pigs (Table 1.3). For pigs, however, barley has the ideal fibre content for fattening quickly. In summer rainfall regions, however, there is no shortage of damaged wheat. This can be mixed with oats in a proportion to give about 5% crude fibre. Oats should be crushed prior to preparing a balanced food ration, which should include meat offals, or some other source of protein, for pigs.
Oats can also enhance resistance of animals to bacterial and parasitic infections. In one study, the oral or parenteral oat β-glucan treatment enhanced the resistance to Staphylococcus aureus and Eimeria vermiformis infection in mice. The β-glucan, extracted from oats, significantly enhanced phagocytic activity (Yun et al. 2003).
Table 1.3 Percentages of nutritive values in oats, barley, wheat and maize.
Valuea |
Oats |
Barley |
Wheat |
Maize |
Dry matter |
86 |
86 |
86 |
86 |
a Values based on all being 86% dry matter; b expressed as megajoules (MJ) per kilogram of feed; c biological value is highest in oats due to favourable amino-acid ratios (Whittemore and Elsley 1976).
In another livestock nutrition study, Flinn and Foot (1992) found oat grain samples ranged from 7-12% protein. Oats with low protein were shown to inhibit microbial activity in the rumen of grazing sheep and needed either green oat pasture or a protein supplement.
All of the varietal samples determined by Craig and Potter (1983) were 12% protein or over in a South Australian study assessing the effects of grazing on various oat varieties. Carbeen, a prostrate growing variety, tested 14.2% protein. Such oat grain would be ideal for drought feeding, when no ‘green feed’ is available.
Origin and genetics of oats
The oat genome
All species of oats have originated in the northern hemisphere. The cultivation of oats is not very old. Neither the Egyptians nor the early Europeans grew oats. De Candolle (1883) ascribed a European origin to our cultivated oats, leaning on historical and philological facts.
The European group of Avena sativa were typical of north-western Europe. A large Mediterranean group, sharply isolated from A. sativa, were A. sterilis and A. byzantina. These three species belong to the hexaploid oats (2n = 42), and can be easily be crossed together or with A. chinensis (2n = 42), the low yielding large naked oat from the Chinese centre of origin.
These are our most important oats for breeding, testing and extension. “2n” represents the number of chromosomes in the sex cells (gametes) after fertilisation. The number of chromosomes before fertilisation is represented by n = 21. These chromosomes, however, each consist of 3 basal groups of chromosomes, each of which has 7 chromosomes. By dividing 7 into 42 we obtain 6, hence the term hexaploid. This represents the genome, the complete complement of genetic material in a cell of this species. Here the genome is written as AACCDD.
The weedy species of A. fatua, or black oats, also belongs to this group. North-western Europe, including Wales, was also a centre for A. strigosa and A. brevis, half weedy, part cultivated diploid species (2n = 14), neither of which can be hybridised with A. sativa or A. byzantina. These wild diploids were noted for resistance to smut, Ustilago avenae, crown rust, Puccinia coronata, as well as mildew, Erysiphe graminis.
Vavilov found many varieties of A. sativa in Mongolia and northern China as well as in Georgia and Armenia, together with A. fatua and A. ludoviciana (Vavilov 1920-1940). These latter two were widely distributed all over south-western Asia. Vavilov found China to be the centre for the large and naked-grain oats, A. chinensis, genetically related to the European oats with chromosome numbers (2n = 42) and easily hybridising with each other. They were first brought from China to Europe in the 5th century AD (Breitschneider 1881). The Author calls this A. chinensis to distinguish it from the small naked oat, A. nuda, which is a diploid (2n = 14), like A. strigosa and A. brevis. Most of the diploid species cannot cross with one another, the exceptions being clauda x eriantha, wiestii x hirtula, wiestii x strigosa, and hirtula x strigosa as listed in Table 1.4. Within the tetraploids, only the following crosses are possible: barbata x vaviloviana, barbata x abyssinica, and vaviloviana x abyssinica. This shows that possession of the same genomes, or sets of chromosomes, does not guarantee interfertility within the diploid or tetraploid species.
Ethiopia, or the highlands of Abyssinia, is the centre of origin for A. abyssinica. Centre of origin is a better term than Vavilov’s centre of type formation, which may have been influenced by Darwin’s term, natural selection. In Table 1.4, the large naked oat created for China, A. chinensis, is on the same line as the small naked oat, A. nuda. This is to show that in the middle column for the tetraploids, a naked oat tetraploid has yet to be found.
Many investigators, as reviewed by Legget and Thomas (1995), thought that the cultivated hexaploid oat had been derived by a simple trichotomy from a common progenitor. This was found to be improbable. If all 3 groups came from a single basic species, the polyploid species (the hexaploids) would have to be autopolyploids but they are not. Autopolyploids are derived by the doubling of the constituent genomes, as by the conversion of AA, the single genome, to AAAA. There is only one oat species like this, A. macrostachya, whose genomic constitution is unclear (Legget and Thomas 1995). This is the only outbreeding and perennial species of Avena and the only one that is autotetraploid. All other oat species are allopolyploids. One fact is certain: the cultivated hexaploid oats did not evolve from any of the known diploid or tetraploid species, because the donor of the DD genome is unknown. The same is true for the hexaploid wheat genome, which also has an unknown donor.
The origin of the third or D genome of the hexaploid (2n = 42) species in cultivated oats varieties is completely unknown. This makes Rajhathy and Thomas’ (1974) theory of oat evolution purely speculative. The discovery of A. canariensis and the magna-murphyi complex in the tetraploid group (2n = 28) of oats is said to realize Vavilov’s law of homologous variation. This is said to be a structural analogy but this does not explain anything. The missing D-genome has never been found in the diploid oat species, which have AA or CC genomes, or in the tetraploid species which have AABB or AACC genomes. Our cultivated hexaploid oats are designated by the AACCDD genome complex. Therefore, on evidence, hexaploid oats cannot have originated from diploids or tetraploids, certainly not by natural crossing, or ‘fusion of distinct genomes,” as postulated by Rajhathy and Thomas (1974).
Table 1.4 Species of Avena genus, the 3 karyotypes and their genomesa.
Diploid = 7 |
Genome |
Tetraploid n= 14 |
Genome |
Hexaploid n = 21 |
Genome |
clauda |
CC |
barbata |
AABB |
fatua |
AACCDD |
eriantha |
CC |
vaviloviana |
AABB |
sterilis: |
|
ventricosa |
CC |
abyssinica |
AABB |
ludoviciana |
AACCDD |
prostrata |
CC |
maroccano |
AACC |
maxima |
AACCDD |
damascena |
AA |
murphyi |
AACC |
macrocarpa |
AACCDD |
longiglumis |
AA |
sativa: hiemis |
AACCDD | ||
canariensis |
AA |
orientalis |
AACCDD | ||
wiestii |
AA |
diffusa |
AACCDD | ||
hirtula |
AA |
bizantina: |
|||
strigosa |
AA |
hiemis |
AACCDD | ||
brevis |
AA |
verna |
AACCDD | ||
nuda |
AA |
chinensis |
AACCDD |
a From Guerin (2003). Note that there is a large diagram on p.154 of the Author’s self-published book referred to here, showing all the crosses that are possible within the Avena genus.
The explanation given is that the donor is either extinct or has evolved into a different species. This depends entirely on the value of the hypothesis itself, that differentiation is a function of time. The possibility that the genome donor may never have existed is not even stated, let alone the alternative which that possibility would imply: separate origin of species in the various Vavilovian centres. This applies both to oats and wheat, Triticum aestivum L., which has a genome complex of AABBDD, in which the donor of the B-genome is unknown. Much ingenious effort and thinking have gone into this work, but we have not yet exploited a fraction of the cultivated oat gene pool.
The significance of multigenic traits
The history of the science of genetics has been a stormy one. The first of the great hybridisers was Joseph Kölreuter, 1733-1806 (see glossary). He described over 500 experiments, including Nicotiana rustica x N. paniculata, which gave a very vigorous hybrid, which was sterile when self-fertilised. It was Gregor Mendel (1822-1884), the father of genetics, who explained the continuous variation in height in Kölreuter’s second generation (F2) tobacco plants after crossing a dwarf with a tall parent. This was the green light or impetus for multigenic plant breeding for traits requiring quantitative or cumulative effects, as for high yielding oats from the Author’s Isolection system.
Between 1900 (when Mendel’s paper was discovered) and 1910, most geneticists could see Mendel’s work as showing only discontinuous variation, looking only at his pea crosses. Mendel, however, had also discovered continuous variation, when he crossed white-flowered and purple-red-flowered beans. This gave an intermediate flower colour (pink) in the F1 progeny and a continuous spread from white to purple-red in the second generation. Geneticists then began to see that alleles (pairs of a gene) had small but cumulative effects with semi-dominance rather than complete dominance, which were behaving in a Mendelian fashion. This gave rise to the multiple-gene hypothesis. This is now one of the most important principles of genetics (Gardner and Snustad, 1984). This principle has been greatly strengthened by the use of statistical methods by R.A. Fisher in England. Fisher laid the foundation for the analysis of variance and the beginnings of experimental design and success in comparing oat variety yields in biometrically designed trials in Australia (Fisher 1925). These trials proved to other plant breeders that yield differences were or were not significant.
The economically significant groups of oats
There are various classifications for oats. These include those based on grain morphology. One can look at the grains after threshing or harvesting and see if the rachilla or stalk remains with the primary grain (Avena sativa) or with the secondary grain (Avena byzantina). Although the varieties Blackbutt and Carbeen derive from the same cross, the latter’s grain articulation is typically A. byzantina, while that of Blackbutt is a 50-50 mixture suggesting its own hybrid origin. Similarly Swan has the hybrid morphology of its sister-line, West. Swan and West belong to the specialised grain oats and therefore another mark of identity is required. The photograph of floret separation in Figure 2.11 of Chapter Two shows this.
The early habit of growth is, however, the best indicator of economic significance. The habit of growth has a significant impact on the economic significance of oats and this is further described under the latter sections in this book that address dual-purpose oat varieties. These groups are prostrate and erect growing varieties and these are further sub-divided into intermediate, semi-erect, erect and very erect (described below). The most reliable mark of identity is whether the juvenile stage has a prostrate (Blackbutt and Carbeen), intermediate (Cooba), semi-erect (Coolabah), erect (Avon, Cassia, Stout and Swan) or a very erect (Moore and West) habit of growth. The prostrate varieties bury their growing point, tiller profusely, resist frost and grazing damage and are therefore dual-purpose varieties, suitable both for grazing and grain production. These two groups of oats, based on growth habit, have been compared in South Australia (Craig and Potter, 1983). This trial was evenly grazed by sheep, which also provided fertiliser and an even grazing. Comparing 0, 1 and 2 grazings, the erect varieties yielded more grain after one grazing than after 0 or 2. The most prostrate variety, Carbeen, was the only variety to yield more grain after 2 grazings than after 0 or 1 grazing in this trial. In this trial, plants were grazed by 100 sheep for 3 days to a uniform height of 2.5 cm above ground level. The prostrate variety, Carbeen, significantly outyielded all other varieties in grain recovery. The variety Carbeen, and the details of this trial, are further described in Chapter Three.
The erect varieties from Western Australia have larger grains than the prostrate varieties from the Glen Innes breeders, and are usually accepted for milling for this reason, and the fact that they are grown in a drier finishing season, which does not discolour the grain. The Glen Innes bred varieties are smaller grained but are higher in groat percentage than varieties bred at Temora, Southern NSW, South Australia and Western Australia. Avena strigosa, cultivar Saia, has very small grains which give it a high volumetric weight. Saia is crown rust resistant and sown in Southern Queensland and Northern NSW coastal areas for cattle grazing. The grains possess up to 20% protein but belong to the diploid species of Avena that cannot be crossed (or only with great difficulties) with the normal cultivated hexaploid species of oats.
Global and economic aspects of the oat crop
Overview
Economic factors, and to some extent political factors, determine the motivation to grow a particular crop or pasture. These factors encompass global agricultural land potential, world population and comparative crop and pasture yields. Some of the data for this study has been taken from the Food and Agriculture Organisation (FAO) of the United Nations annual reports from 1948 to 1992. This data has been assembled and critically evaluated by Sassone (1994) and further elaborated by the Author in the remainder of this chapter2.
Oats, mainly Avena sativa and A. byzantina, have an important role in world pasture production. Considerable research and developments have been conducted on this crop in Australia and overseas. The application of research findings in agriculture has contributed to overcoming world food shortages (Sassone, 1994). Such has been the impact of improved practices in agriculture that countries in Asia, for example, are now demanding more milk products and meat in the diet as compared with traditional foods, in particular, rice. United Nations Yearbooks show that even with population increases of about 20%, the number of telephones, refrigerators and other amenities in third world countries have approximately doubled. Average real incomes have more than doubled (UNICEF, 1993).
This demand for milk and meat products now increases the need for more efficient means of their production, including improved pastures and grain production. The role of dual-purpose grain types, oats grown for both grazing and grain production, to assist these developing countries to meet their demands in the Southern Hemisphere, including Australia, has been identified as being important (Guerin, 1961; Guerin and Guerin, 1992). Oats is not a coarse grain only, or a source of carbohydrate only such as wheat and rice (Whittemore and Elsley, 1976). Oats, however, possesses other characteristics which make it unique as a food source for both humans and livestock and these have been described earlier in this chapter. Due to favourable amino-acid ratios, oats have a higher biological value than barley, wheat or maize. Along with the cholesterol lowering attributes of the grains, oats can be considered as “the health crop”.
Global trends in population, food supplies and diets
Population growth or rate of increases is defined as the birth rate minus the death rate. As of 1990, this value for the world was 1.7%. Africa has the highest rate of increase in the world at 3.0% (Table 1.5). Asia and Latin America also have the second and third fastest rates of increase. The first world continents, Europe, North America and the former Soviet Union are increasing at less than 1%. These latter regions have fertility rates below 2.2 children per female, which represents the replacement or zero population rate. Sassone (1994) predicts that world populations may begin to decrease by the year 2050.
Based on the FAO data, it is evident that world food production has increased, regardless of world population growth. Over the period studied by Sassone (1994), food production, especially rice and meat, quadrupled, while world population has little more than doubled. It is apparent that farmers in the developing world have adopted many of the new technologies and developments in agricultural science, which have dramatically improved crop yields. Intense effort by agricultural extension practitioners in developing countries have improved the rates of adoption of appropriate technologies for both grain and pasture production in these countries. These adoptions have included improved understanding of the need for fertilisers, pesticides, herbicides, soil tillage practices, and the growing of improved crop and pasture varieties. In India for example, on average, the population consumes the 2,200 calories recommended by the Food and Nutrition Board (Sassone, 1994). Developing countries in the Far East increased grain production by 12% while in Africa, grain production increased by 47% (Sassone, 1994).
Meat production consistently increased from 1981 to 1990 (Table 1.6). Total cereal tonnages, including wheat and rice, declined in volume over the same period. An inference that can be made from this data is that the area of land under pasture is likely to be increasing.
World grain prices fell after 1981, while stocks of grain rapidly increased (Sassone 1994). Supply controls were applied in most countries in the form of acreage reduction measures. During 1981-85, difficulties stemmed from depressed agricultural exports, high interest rates, and supply surpluses. In Australia this effect was particularly marked where meat production increased 22% from 1984-91.
In the developed nations, farmers reduced grain production after 1984 because of massive grain surpluses. Farmers of the Near East and of Africa, on the other hand, increased grain production by over 40% between 1984 and 1991.
The expansion of land areas used for rice and meat production has broader implications for integrating more balanced diets into the households of developing countries. Furthermore, the increased area of land devoted to pastures reflects the potential of increased crop rotations and ley farming and, therefore, general soil improvement.
Table 1.5 World population densitiesa.
Location |
Population |
Population |
Population Increase |
Land Area |
Population Densityb |
World |
4,448 |
5,292 |
1.7 |
136,255 |
39 |
Africa |
477 |
642 |
3.0 |
30,305 |
22 |
Asia |
2,583 |
3,171 |
1.9 |
27,582 |
115 |
Latin America |
363 |
448 |
2.1 |
20,535 |
22 |
North America |
252 |
278 |
0.8 |
21,962 |
13 |
Europe |
484 |
498 |
0.2 |
4,933 |
101 |
Oceania |
22.8 |
26.5 |
1.5 |
8,536 |
3 |
Former USSR |
266 |
289 |
0.8 |
22,402 |
13 |
a Sassone (1994); bP = Individual persons.
Table 1.6 Food production and population growtha.
Year |
World Tonnes (x 106) | ||||
1948-52 |
1960 |
1970 |
1980 |
1990 | |
Total cereals |
NAb |
NA |
1215 |
1566 |
1952 |
Wheat |
155 |
222 |
318 |
446 |
597 |
Rice |
111 |
158 |
316 |
399 |
518 |
Total meat production |
40 |
60 |
107 |
133 |
175 |
Population (x106) |
2516 |
3020 |
3698 |
4448 |
5292 |
a Sassone (1994) from Food and Agriculture Organisation of the UN annual reports; b NA = not available.
Table 1.7 Changes in total grain yields and reduction in total crop growing areaa.
Cropping Years |
Cropping Area |
Total Grain Production |
Yield |
1975/76 |
707.7 |
1236.8 |
1.75 |
1980/81 |
721.8 |
1427.2 |
1.98 |
1985/86 |
715.0 |
1645.6 |
2.30 |
1989/90 |
693.3 |
1665.8 |
2.40 |
1992/93 |
687.7 |
1758.5 |
2.56 |
a From World Grain Situation and Outlook (USDA, 1993).
Table 1.8 Annual rate of change (%) of increase in production of farm productsa.
Produce |
World Tonnes (x 106) | ||||
1981 |
1986 |
1990 |
1991 |
Change (%) | |
Total cereals |
1646 |
1854 |
1971 |
1887 |
1.45 |
Wheat |
454 |
535 |
601 |
553 |
1.97 |
Paddy rice |
412 |
471 |
522 |
518 |
2.26 |
Total meat |
138 |
157 |
176 |
179 |
2.87 |
a Sassone (1994).
International increases in cereal grain yields
World cereal grain yields have increased marginally in the period 1979 to 1994. The greatest increase was observed with the wheat crop. The increases in barley and oat yields were lower over the same period. While the total tonnage of wheat and barley have increased over this time, world oat yields “appear” to have decreased slightly. However, the accuracy of Australian oat yield statistics do not reflect actual yields because the oat crop is typically grazed throughout the growing season prior to harvest and considerably less stringent agronomic management is applied to this crop than to other cereals, in particular wheat and barley (Simmons, 1987).
World grain production multiplied by 2.6 from 1950 to 1984 at the same time that the world human population less than doubled. The price of grain decreased over the same period and removed farmer’s incentives to grow more. In the 1950s and 1960s, a bushel of grain was worth the equivalent in dollar value of a barrel of crude oil. In the 1970s and 1980s, the price of grain in real terms was approximately 20% of the 1950 price, allowing for inflation, or 10% of the price of a barrel of crude oil. Farmers in the developed world therefore reduced grain production after 1984.
Total world grain yields increased substantially over the period of 1976 to 1993 from 1.75 to 2.56 t/ha (Table 1.7). Over the same period, the total area of land used for grain production decreased from 7.08 x 108 ha to 6.88 x 108 ha. However, there was a temporary increase during this period to 7.22 x 108 and 7.15 x108 during the years 1981/82 and 1985/86, respectively.
As a result of this increased productivity in grain production, approximately 30x106 ha have been made available for other agricultural activities including the growing of improved pastures. This increased availability of land for pasture production has increased the potential for dual-purpose grazing cereals, including oats. There is evidence that this has occurred from the increase in total meat production worldwide (Tables 1.5 and 1.8). This total increase in meat production, however, does not include increases due to the increased total number of lot-fed livestock and other intensive livestock industries. World-wide, approximately 22% of the land area has potential to be used for pasture. This does not include the 11% of arable land or the 30% estimated to be utilised in forestry. India utilises 92% of its agricultural potential without using the 18% of its total area that is devoted to forestry.
The arable area of Australia of 48 million ha includes 17 million ha of crops and 31 million ha of sown pasture and grasses. Forestry includes 41 million ha of native forest, 1 million of plantation forestry and 36.5 million ha of protected wilderness areas, national parks and conservation areas (Table 1.9).
The greatest part of Australia’s agriculturally potential land area of 419 million ha is used for grazing. In no other country or continent has livestock production dominated agriculture as in Australia. Hence Australia has played a leading role in the development of pasture improvement and development of dual-purpose oat varieties. Furthermore, Australia has a large potential to improve its dual-purpose oat and hence livestock production.
Table 1.9 World land utilisationa.
Region |
Total Area (T) (ha x 106) |
Agricultural Potential (ha x 106) |
Arable Area |
Pasture Potential (ha x 106) |
Forestry Area |
Unusable |
World |
13,392 |
4,407 |
1,406 (11) |
3,001 |
4,068 (30) |
4,917 |
Africa |
3,030 |
1,047 |
204 (7) |
843 |
629 (21) |
1,354 |
North America |
2,241 |
627 |
253 (12) |
374 |
815 (36) |
799 |
South America |
1,784 |
497 |
89 (5) |
408 |
927 (52) |
360 |
Asia |
2,753 |
893 |
444 (16) |
449 |
565 (21) |
1,295 |
China |
956 |
287 |
109 (11) |
178 |
77 (8) |
592 |
India |
328 |
178 |
164 (50) |
14 |
61 (18) |
89 |
Indonesia |
190 |
13 |
13 (7) |
0 |
152 (80) |
25 |
Japan |
37 |
7 |
7 (19) |
0 |
25 (68) |
5 |
Europe |
493 |
240 |
149 (30) |
91 |
140 (28) |
113 |
Holland |
3.6 |
2.2 |
0.91 (25) |
1.3 |
0.3 (8) |
1.1 |
UK |
24.4 |
19.4 |
7.4 (28) |
12 |
1.9 (8) |
3.1 |
Australia |
768 |
467 |
48 (6) |
419 |
77 (10) |
224 |
a Sassone (1994).
While there is a link between oat crop yields and the length of the growing season, on a world basis (Table 1.10) (Forsberg 1986), there also appears to be a link between high oat yields and high population density, but a closer correlation exists between high oat yields and the “nurturing” or constructive policies of the mixed economy (private and socialist enterprises) of the European Union. The small-scale, isolated nature of agricultural production, relative to urban industries in the European countries makes state aid essential. O'Brien (1929) showed how Germany led the world in this respect, followed by Denmark and France. England was indifferent to rural problems, due to her espousal of free trade (see glossary), except in wartime when feverish efforts were made to increase crop yields.
Australia has inherited the same predilection for free trade with disastrous repercussions on both agriculture and manufacturing industries. Cribb (1982) portrays in detail this state of Australian agriculture. Free trade is stated to be an “optimal” policy for a small, open and competitive economy. A small economy is defined as having negligible market power and one that cannot influence the equilibrium prices in world markets by its trade policy. Protection may create sheltered markets and monopolies with little incentive for producers to be efficient (Parikh et al. 1988).
Fair trade, however, is necessary to protect farm families as is being done in the European Union under the revamped Common Agricultural Policy. Countries will become more self-supporting and trade-restrictive in the future, as free trade inflicts further economic damage on countries like Australia.
Table 1.10 Oat yields, growing days, population density and agricultural policy.
Country |
Yields (t/ha)a |
Growing daysa |
People/km2 b |
Policyc |
Ireland |
4.68 |
142 |
49 |
Nurturing |
a 1983 data from Forsberg (1986); b Russell and Coupe (1987); c O'Brien (1929), though a dated reference, is provided for background; d not available.
Advantages of grazing the oat crop
Craig and Potter (1983), however, point out advantages of grazing the oat crop: (A) Stimulating tillering and increased number of grain producing lateral shoots; (B) Reducing the incidence of fungal diseases common in ungrazed crops; and (C) Reduction in lodging by promoting stronger shoots and removing excess leaf area. Craig and Potter (1983) also found that nearby annual pasture carried 8 ewes/ha giving 1450 kg/ha and 1830 kg/ha feed in early August and early September respectively.
Another advantage of oats was the ‘saved pasture’ on which Crofts (1966) carried 7.4 ewes/ha at Orange, NSW. This was twice the rate of grazed ryegrass-clover pastures yielding 4.5 kg dry matter/ha/day and only one-fourth that of heavily seeded oats given N fertiliser (Table 1.11).
Table 1.11 Stocking capacity of oats compared with other pasturesa.
Treatment |
Dry Matter Yields |
Stocking Rate | |
kg/ha |
kg/ha/day | ||
Ryegrass-clover (A) |
448 |
4.5 |
3.7 |
Saved Pasture (B) |
840 |
8.4 |
7.4 |
Oats @ 90kg/ha seeding rate (C) |
1680 |
16.8 |
14.8 |
Oats @ 179kg/ha seeding rate + 67 kg/ha N (D) |
3360 |
33.6 |
29.6 |
Ratio of D:A Treatments |
7.5:1 |
7.5:1 |
8:1 |
a From the trial conducted in Orange and reported by Crofts (1966). Records for a 100 day winter (late May to August).
Clover-grass pastures grow abundantly in early summer but very slowly in winter in comparison with winter or dual-purpose oats. Oats grow 4 to 8 times as rapidly as pasture (Crofts, 1966) during the 100-day winter at Orange NSW, Australia. This result was achieved with the old variety, Algerian, which gave at Richmond NSW, in a separate trial, less than one-seventh the July yield of the High-vigour oat, Blackbutt. Therefore, oats and pasture are both necessary for good livestock husbandry.
To further demonstrate the significance of the oat crop for grazing, even without N fertiliser added, oats gave 4 times the stocking rate given by ryegrass-clover pastures and the dry matter recorded 18% crude protein (Crofts 1966). Crofts (1966) also found that oats should be planted when the mean daily temperature approaches 18°C (or 65 Fahrenheit), which at Orange is about early March, and early April for lower elevation locations. By shutting up large areas of oats in early September, soon after grazing, Crofts (1966) in no time could still recover one tonne of grain per ha.
Although drier winters are better for pasturing sheep and cattle on an annual pasture like oats, there is considerable potential untapped in the southern areas of NSW. In the winter rainfall zone at Orange, NSW, Crofts (1966) obtained a remarkable response with Algerian (liable to frost damage in the severe winters in New England), and to heavy rates of seeding and nitrogen in 1962 and 1963. Algerian produced 3.4 tonnes per ha, 7.5 times the yield of improved pastures and carried 29.6 sheep per ha, 8 times as many ewes as the clover-ryegrass pasture during the 100-day winter period and carried 30 ewes per ha. The extra yield from nitrogen was less expensive than quality pasture hay. By excluding sheep from the crop from early September onwards, the 1 tonne per ha grain recovery obtained could be sold to offset total costs, including 179kg of seed and 67kg elemental nitrogen per ha. Alternatively, the grain could be kept as a drought reserve (Crofts 1966). Algerian, however, could not produce such yields in a year like 1961 on the New England Tablelands, due to frost damage.
Forsberg and Reeves (1995) found that oats, next to rye (Secale cereale L.) are the most versatile of the cereals regarding suitable soil type. Maximum oat yields require soil pH of 5.3-5.7 but can tolerate acid soils with a soil pH of 4.5. Nutrient (NPK) needs for oats are less than those for wheat (Triticum spp.) or corn (Zea mays L) and can be tailored to the desired yield level.
Oat production statistics and limitations to their interpretation
Overcoming the limitations of statistics is critical in maximising the productivity of the oat crop. Government or industry compiled statistics typically have little value in guiding the direction of research or funding of oat breeding programs. It is more profitable to study a few statistically designed, well-managed and executed yield trials, as described in the latter chapters of this book.
The world statistics (Table 1.10) given do not record the 1-2 tonnes of herbage dry matter produced on many farms during the long growing season such as in NSW, Australia. This is not recorded in the state and national yield statistics. This claim is supported by Mengersen (1963) who at that time, estimated that at least 70% of the NSW oat crop is used for dual-purpose production, that is, one or more grazings and then grain recovery. This is a very important aspect of oat production that unfortunately is not reflected in state and national yield statistics.
Other examples include the reported statistical oat yields in Ireland. Ireland, although possessing the world's highest average yield, result from late spring sowings and could be boosted further by winter or dual-purpose oats that utilise a longer growing season. The same applies to China as well as to NSW, where late sowings result in low yielding crops that are far behind actual Government research findings in NSW, as recorded here. Oat yields at Cowra, NSW, have been higher than any values reported in world statistics. The research plots at Cowra were not irrigated and yet out-yielded the irrigated trial at Coleambally. At Richmond on the eastern coast of NSW, a dual-purpose oat line, P4315, produced over 10 tonnes of biomass per ha in a dry season (50% of the normal rainfall) without irrigation. Other examples are described in the following chapters.
Statistics on oat production in NSW have been documented for many years. These figures give little indication of oat yield potential, however, and are of minor value only because they do not always report which varieties were sown, soil types, sowing dates or if the crop was grazed and for how long. This has been the case at least in NSW. NSW oat production statistics, which are composite data compiled by the NSW Government, and grouped from all regions of the state, are criticised because of their failure to show the differences between the summer rainfall northern zone and the winter rainfall southern zone. Furthermore, such oat production statistics do not reflect the total biomass yield or the total value that the oat crop contributes to farming systems. The application of these statistics has led to a frost susceptible oat variety being used for pasture research at Armidale (1977), after the frost resistant Blackbutt had already been released to farmers in 1975. Shortcomings in government statistics result in poor funding of oat research. Political economy, sociology and lack of knowledge of agronomy and the value of oats for human and livestock nutrition, are also inhibiting the further exploitation of the oat crop. Figure 1.1 shows cereal production statistics since 1981.
In 1990, only Scone and Windouran (both in NSW) showed higher yields for oats than for wheat and barley (Fitzsimmons, 1990). Before 1982, even in 8 irrigation Shires, wheat and barley outyielded oats in production of grain. Beginning in 1982 at Leeton, NSW, oat yields started to rise above those of wheat and barley (Table 4.1, Chapter Four). During the previous 52 years from 1930 to 1982, the wheat and barley yields were always higher than those of oats, and barley was the highest yielder until 1960. From 1960 onwards, wheat took over as the highest yielder of the three cereals and continued so into the 1983 - 1990 period. Shires in NSW in which oat grain yields are superior to those of wheat grain are those in which irrigation is available. In these areas excessive grazing is physically impossible and less likely than the production of crops for grain and this is described in detail in Chapter Four.
The Australian statistics (Cribb 1991) are also misleading because oats yield higher than wheat and barley in the medium to higher rainfall zones (>500 mm) and oat breeders have been forced to create early maturing lines like Cooba and Coolabah to be harvestable even earlier than the early wheats.
There are other limitations to the value of oat and cereal grain yield statistics. Even when the Bureau of Statistics gives the areas of oats that are grazed, it is important to know the name and characteristics of the actual variety of oats that was grown. In many cases specialised grain varieties, usually from Western Australia, have been grazed in the colder, drier winters of NSW and because of their frost and grazing susceptibility have not recovered much, if any, grain.
The comparative statistical cereal yield data presented in Figure 1.1 may suggest that a shorter season variety like Cooba or Coolabah is invariably chosen to avoid a clash with wheat harvest, with the result being a reduced yield. This is counter intuitive because in a wet harvest period, wheat takes much longer to dry out than oats, and in a very short time after rain, the oats can be harvested. This enables better use of expensive harvesting equipment during the harvest season, even if grain storage facilities have to be increased, or organised more efficiently. Longer season cultivars can be safely harvested in the higher rainfall wheat areas, using Glen Innes to breed rust resistance.
Another important factor in statistics is the length of the growing season, which can vary from year to year, and the response of the oat variety. This can be broken down into the following traits: (A) the length of the vegetative period of the variety, (B) its response to frost or vernalisation, and (C) how rapidly it can flower and set grain after the last day of grazing.
The “statistical” Australian oat yield is a fraction of the actual yield, due to the grazing tonnage not being recorded. As a result, oat research receives only a fraction of the funds due to it in Australia where every other crop is funded on the basis of its total tonnage delivered to a government agency or entering commercial channels. In turn, Australian farmers are denied the benefits of more thorough and long-term research and plant breeding in oats.
Appendix A contains further statistical data on oat yields in Australia.
Figure 1.1 Statistical yields of the major cereals grown in NSW.
Extension of research to oat growers
With so much research and extension of information to farmers on other cash crops, relatively little advice appears to be extended to the farmer’s oat crop, which experiences more environmental stress than any other because of its versatility.
While plant breeders in the winter rainfall areas of Australia have produced dual-purpose oats with particular emphasis on grain yields, with at least 70% of the total area sown to oats during the 1960s for dual-purpose grain and grazing (Mengersen, 1963), there is a gap between oat breeding research, which has created new dual-purpose varieties, and farm practice. This is due to a lack of knowledge and skill relative to the oat crop for a particular location, soil and climate.
A similar lack of skill in wheat growing would result in uneconomic yields of wheat. Prevention of Ophiobolus attacks on wheat requires that wheat should follow a crop of early sown, well-grazed oats, to kill susceptible grasses that spread Take-all disease (Lazenby and Matheson 1975). Heavy grazing of oats in cool winters will also destroy black oats (A. fatua and others).
It is anticipated that the research presented throughout this book on the value of the oat crop to farmers will help fill the gap between scientific research into the further development of oats as a pasture and grain crop and farming practice.
Conclusions
There is now ample evidence to demonstrate that oats play an important role in human and livestock nutrition. Oats provides grain for humans and livestock, a grazing or forage crop for livestock, and the health benefits of oats are predominantly the cardiovascular disease prevention properties of oats (through the cholesterol lowering effects of β-glucan) and the glycemic effects of oats which is to reduce the increase in human blood glucose levels.
While the significance of the oat grain in benefiting human health has received considerable attention, however, relatively little attention has been given to the important attribute of combined grazing, grain production and total crop value in global agriculture. The oat crop, because of its potential for grain recovery after grazing, has a significant role to play in increasing global pasture production. Particular oat groups, specifically those with prostrate growth habit, have the required attributes for inclusion in breeding programs to develop suitable oat varieties for dual-purpose capability and therefore for increasing pasture production.
The application of oat statistics by government agencies is holding back the attainment of higher oat yields in Australia. Governments should review how oat production statistics are used and recognise that these typically underestimate the overall value of the oat crop in achieving sustainable farming systems.
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2 The Author also acknowledges the extensive work done by the FAO on the global and economic importance of the oat crop and readers are encouraged to view this information at the FAO website for further details at www.fao.org.
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