Feeding cereal grains to livestock: moist vs dry grain

High-moisture grains can be preserved whole or crimped. Regardless of method, all grain harvested at above 14.5% moisture content should be treated with an appropriate preservative as quickly as possible after harvest, to reduce spoilage and nutrient loss.

Grain harvested at a moisture level over 30% contains soluble carbohydrates (sugar) and supplies digestible fibre from its unlignified seed coat. Effective preservation will retain these nutrients.

At a moisture content of 25–40%, grain can be crimped, treated with either acids or inoculants and ensiled within 24 hours of harvest, or it can be treated with urea and stored under a sealed sheet to contain the ammonia gas.

Grain harvested at moisture contents of 15–25% can be treated with propionic acid, after which it will keep for up to 12 months, depending on the quantity added. Alternatively, as long as the seed coat is not green, it can be treated with an alkaline-ammonia-release product, which, as well as preserving it, will increase crude protein content.

The grain is mechanically flattened, causing the seed coat to break open. The addition of an effective preservative is required to restrict fermentation and improve aerobic stability, stopping the growth of yeasts and reducing heating during ensiling and feed-out. It requires a structurally safe, airtight clamp for storage. Vermin control is required.

Feed-grade urea prills are added to moist whole grains immediately after harvest (within 12 hours) to preserve the crop. They make the seed coat more digestible and increase the crude protein content to around 18%. Thorough mixing of the urea into the grains is required, to avoid nutritional problems. Fertiliser-grade urea should be avoided as it may contain heavy metals. The urea treatment deters vermin.

Caustic soda (sodium hydroxide) works by breaking the seed coat of the grain, so it can be fed to animals without further processing.

There is a large moisture range for this type of treatment and the harvest window is wider. An additional benefit is that it is relatively alkaline and can help reduce the risk of acidosis, especially if treating wheat.

Grain can be treated dry by adding the appropriate amount of water at the time of mixing with the caustic soda. It is important to obtain the correct application rate from the caustic-soda supplier. It is a hazardous chemical and should be handled with care, adhering to safety instructions.

The grain can be harvested with a conventional combine and then rolled or harvested with a forage harvester, fitted with a grain mill. Ammonia-releasing pellets need to be applied promptly after harvest and then the grain sealed in a clamp.

Grain can be harvested between 15–25% moisture and can be combined in slightly damp conditions, as a small amount of surface water can help processing. However, make sure the crop is fully mature, because immature and green grain have a higher level of sugar, which will affect preservation.

The alkaline pH produced can act as a buffer, which can improve rumen function. Crude protein content is also increased by 3–4 percentage units of DM, depending on pellet application rate.

Non-corrosive forms of propionic acid are available that can be applied to either whole or processed grains under 25% moisture content. Grain should be treated straight off the combine to avoid drying costs.

Treated grain does not need to be clamped but stored in a clean, dry, covered area or bunker. This option avoids the need to dry grain that is nearly at the conventional harvest stage. It also keeps the grain cool and discourages mites and weevils.

When feeding moist grain, the amount fed should be adjusted to give the required dry matter intake. For example:

If unfamiliar with feeding moist grains, seek professional nutritional advice, as they are nutritionally different from dry grains.

Crimped grain provides a high-energy, moist feed, which could replace dry combined grain.

The starch is fermented more slowly than ground/rolled cereals, so the cereal inclusion rate can be increased without heightening the risk of acidosis, if fed in a correctly balanced ration.

Crimped grain, while not higher in protein than the original grain, does have a higher protein availability than later-harvested crops. Also, the ability to harvest grain two to three weeks earlier than conventional harvesting reduces losses from grain shedding and provides an opportunity for establishing a forage crop in the rotation. The feed value of straw is also increased by the earlier harvesting, although it may require drying in the field before baling.

Urea-treated grain can be fed whole but should be soaked before feeding if grains are seen coming through in the dung. While high in protein, it is mainly in the form of non-protein nitrogen, so feeding other sources of less rapidly degradable protein may be worthwhile for some classes of livestock. It also requires high-sulphur minerals to be fed, but feeding high levels of urea-treated grain can make copper more readily available, so avoid using high-copper minerals. Storage of moist grains will reduce vitamin E and selenium content, due to fermentation and the oxidation process.

While further processing is not required before feeding, it needs to be thoroughly mixed in a diet feeder with the other components. High in sodium, this feed needs a low-salt mineral and should not be fed ad lib. Increased urine output may occur, which will increase bedding requirement.

The grain should be left in a sealed clamp for at least two to three weeks. Alkaline-ammonia-treated grain needs to be rolled before feeding. Can be fed to all categories of stock over three months of age. Its alkalinity has a beneficial effect on rumen stability. Sulphur and iodine supplementation is recommended with ammonia-treated grain, along with vitamin E and selenium.

The treated grain is highly digestible and should be rolled as coarsely as possible, maintaining large particle size to reduce the risk of acidosis. As with other moist grain treatments, vitamin E and selenium supplementation is required.

Grains with a moisture content below 14% are considered dry. They do not require additive treatment and can be stored loose under cover. The main species used are maize, barley, wheat, oats, triticale.

Very dry grain can be difficult to roll without it breaking into fine particles. The starch is then very quickly fermented in the rumen and more likely to cause . Acidosis occurs when grain rapidly releases carbohydrates into the animal’s rumen, which then ferment rather than being digested normally. Bacteria in the rumen produce lactic acid, which slows the gut down and can lead to dehydration, bloating and even death if not treated immediately. If possible, feed a digestible fibre source with dry cereals, such as sugar-beet pulp, oats or soya hulls. For example, include at a rate of 10% with barley and up to 35% with wheat, depending on the processing method and cereal fed.

Alternatively, dampen the grain with water a few hours before processing to soften the seed coat, to help avoid grain shatter. Be careful this does not cause the grain to heat and produce mould if stored too long or create blockages in hopper feeders.

Cereals are often deficient in protein for the class of stock being fed; digestible fibre content is low in wheat and triticale, and the grains can be deficient in calcium and vitamins A, D and E. Devise rations with the appropriate nutritional and mineral/vitamin balance.

Straw can be either harvested dry and baled, or baled and/or ensiled wetter as strawlage, for example after crimping. Strawlage can be expected to analyse with an ME up to 7 MJ/kg DM and CP 4.5–6% in the DM, compared with dry straw at 6 MJ/kg DM and 4% CP.

Moist straw (80–85% DM) can be treated with ammonia or ammonia-releasing urea-based pellets, such as the alkaline wholecrop and alkaline-ammonia grain treatments. These will increase its protein content from 4% to 8–10% CP and improve its digestibility. Treated straw contains virtually no vitamins, minerals or trace elements and needs additional sulphur. Speak to the mineral supplier or a rumen nutritionist before feeding ammonia-treated straw.

This type of straw can be fed as a sole forage, along with the appropriate supplementary energy source and minerals. It can also be fed alongside other forages as a ‘forage extender’ or ‘replacer’, but care must be taken to balance the ration appropriately. Always seek nutritional advice before feeding.