Oats (Avena sativa)

Oats is the traditional and still the most popular, grain fed to horses as a starch based energy source. It is grown in most cereal growing areas in Australia.

Major Advantages

• Oats is a "safe" grain to feed because of its high crude fibre content (10%) in | the outer hull, which dilutes its starch content, helping to reduce the risk of digestive upset and laminitis if excess is fed relative to needs.
• Whole oats contains the lowest amount of starch but the highest proportion of starch digested in the small intestine, ranging from 61 - 83%, followed by sorghum, corn and barley. Processing oats by crimping, rolling or grinding does not significantly improve digestibility of its starch in the small intestine, j
• Oats can be fed alone or with roughage, such as Lucerne hay or chaff, to maintain a horse at pasture during winter, or when fed out in controlled amount not exceeding 0.5kg / 100kg body weight in a meal during drought conditions.
• The protective husk reduces the risk of deterioration of whole oats by moulds and insect attack during storage.

Major disadvantages

• Oats has the lowest digestible energy concentration of any cereal grain, although it is well digested in the small intestine. This increases the bulk that | has to be fed as an energy needs may not be able to be consumed in small-framed horses or those that develop a poor appetite when worked hard.
• Foals and horses with poor teeth, such as aged horses, or greedy horses that do not chew their feed thoroughly, obtain less nutritional benefit from whole oats. Crimped oats is better utilized in these horses.
• Oats has greater variability in crude protein, fibre content in its hulls, and weight than other cereal grains. It has lower yield per hectare than corn, barley and sorghum commonly used for livestock feed. Oats grown under dry conditions has almost twice the crude protein content (12%CP) as compared to 6 _ 7%CP for very plump oats, cultivated under wet conditions.
• The higher phosphorus content, in the form of phytate in oats, has a greater binding effect on calcium, magnesium, zinc and iron relative to the other cereal grains.
• The fermentation of its higher fibre content in the hindgut increases the "heat
  waste" during fermentation, which adds to the overall heat load of horses in
  hard work that are fed oats as the primary energy source under hot conditions!
• Feeding even a relatively small amount of oats has been associated with an increased risk of "tying-up" and nervy, hyperactive behaviour in some individual horses.

Selection and Quality
The quality of oats is evaluated by weight, the plumpness of the seed, contamination with plant material, weed seeds, dust, moulds and presence of Weevils. It should weigh about 500g / litre. Oat grains that are long and narrow in shape have a higher proportion of fibre and a lower digestible energy and crude protein content.

Processing
Oats is normally fed as whole grain. Oats can be processed to break open the kernel by rolling to produce crimped or "•bruised" oats. Crimping and rolling oats does not significantly increase the digestion of starch in the small intestine. Any form of rolling or crimping can increase the dust content and rate of deterioration during storage, as compared to whole grain.
Clipped oats or "racehorse oats" is produced by removing the pointed ends of the fibrous hull, increasing the relative starch to fibre content and therefore the energy density of the grain. Normally 10% less in weight can be fed as compared to whole oats to provide an equal amount of energy.

Nutrient Composition of Grains
(Average value as fed, 90% Dry Matter, unless otherwise stated)

Source: AFIC (1987), NRC (1989), Ensminger at al (1990), Lewis (1995), Frape (1997), Feedstuffs Annual (1997)