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High-quality forage is the key to reducing feed costs. This is done by harvesting and storing a high-yielding, good-quality crop of forage. When a crop such as alfalfa is cut just before flowering and harvested quickly under good weather conditions, protein and energy levels above 25 and 65 per cent are possible. Late harvesting decreases the crude protein content, dry matter digestibility and dry matter intake of the forage.
One of the most important factors affecting forage quality is the state of maturity at cutting. Young, vegetative forage is higher in protein and energy than older, flowering material. Quality of first-cut alfalfa drops especially quickly. Producers aiming for a very high-quality forage (for example for dairy cows or cash hay sales) should consider cutting as early as June 10-15.
Relative Feed Value (RFV) is an indicator of forage quality, based on a combination of acid detergent fibre (ADF) and neutral detergent fibre (NDF). For high-quality hay to be fed to dairy cows or sold in the cash hay market, an RFV of 150 is considered ideal.
The feeding value of leaves is considerably higher than that of stems. Loss of leaves in handling decreases feed value. Leaf losses are likely to occur when legumes are cut and raked for hay, but can be minimized by harvesting with a mower conditioner.
Large losses in feeding value may result when hay is exposed to weather. Rapid-curing, collection and proper storage of forage reduces these losses. Table 18 summarizes the types and magnitude of losses that may be expected under good management and harvesting conditions. Much higher losses are possible with all systems under fair or poor conditions. These figures are valid only if proper care and management are provided to all harvesting and storage operations.
Knowing dry matter content is important when harvesting, or buying and selling forage. Forage dry matter content can be easily determined in a few minutes, using a microwave oven and a small fish or diet scale.
Forage Dry Matter calculation:
(final wt of sample) - (wt of plate)
x 100 per cent = per cent forage
|150-100 x 100 per cent = 25 per cent forage dry matter|
Table 18: Dry matter losses of hay and silage during harvesting and storage.
|Dry Matter Losses (per cent)|
|Silage||Silage||Square Bales||Round Bales||Loose Stacks|
|Respiration and weathering||6||4||10||10||9|
|Usual storage method: (a) Steel-tower silo, (b) Bunker silo sealed with plastic cover, (c) Hay shelter, (d) Outside storage|
Harvesting silage in round bales can be an economical means of reducing losses when faced with uncertain weather. Benefits include being able to use existing round-bale equipment, and lower field and feeding losses than with dry hay. Because stands with a high sugar content ensile well, best results are usually found with mixed alfalfa-grass stands cut at an early growth stage. Stands receiving rain in the swath should not be harvested as round-bale silage, because the bacteria needed for ensiling cannot compete with soil bacteria splashed onto the forage by rain. Before baling, ensure that bale handling equipment can handle the heavier bales, which can weigh as much as 2,800 lb for a 6-foot bale. Do not cut more in one day than you can bale and stack in a day. Bale at 40-60 per cent moisture. In most cases, this is achieved by baling the day after cutting. Baling too wet results in butyric acid (sour silage) production and increased freezing of the bales, and baling too dry results in greater quantities of air in the bale and mouldy silage. Seal bales in plastic as soon as possible, and always the same day. Storage options include using sheet plastic over a pyramid stack, single-row tube, and tube wrapping, or individual bale wrap. Monitor silage wrap for holes and tape holes shut with duct or construction tape.
Ammoniation can be used when storing damp hay or to improve the feeding value of low-quality forages. Ammonia (NH3), which contains nitrogen, increases the protein content of low-quality feed. It further increases the feeding value by assisting in the breakdown of the poorly digested lignin fraction of mature forages.
In addition, ammonia acts as a preservative, allowing forages to be safely harvested at higher moisture levels. Bacteria and moulds are destroyed during the ammoniation process, preventing overheating. This results in a safer and more palatable end-product, with less destruction of plant nutrients during storage. It also reduces field harvesting losses and is less weather dependent.
For a description of the ammoniation process and the safety precautions required, refer to Manitoba Agriculture and Food fact sheet Ammoniation of Forages.