The different types of feeds undergo different types of processing for digestibilty purposes, ease of delivery, and consistency in the diet.
Grains – processing improves rate of digestion. The hull (shell) of grain seeds is highly indigestible by ruminal microbes as well as digestive enzymes. Most processing methods improve digestibility by opening/breaking the shell, exposing the more digestible interior (starch) as well as by increasing the overall surface area available to digestive enzymes and ruminal microbes. The more seeds are processed, the faster the rate of digestion. Typical processing methods include:
- Grinding- processed with a hammermill (rotating hammers which crush the grain until it is small enough to fit through a screen)
- Flaking – grain is exposed to lots of stream or high pressure then rolled
- Dry rolling – grain is compressed by rollers; effect of processing on size (fine vs course) depends on weight of the rollers, grooves on surface of the rollers, moisture content of the grain and rate of flow of grain through the rollers
- Crimping – also known as steam rolling; grain is steamed for a short period of time before being passed through rollers.
- Pelleting – ground or rolled grain is forced through a small openings under pressure to produce pellets. Can add supplements or feed additives to grain during pelleting process.
Oilseed Meals – by-product from the extraction of oil. Many processing techniques can be used; in general, grains are cracked, oil (fat) is extracted and the remaining flakes are dried/roasted then crushed. The digestibility value of an oilseed meal increases with the amount of processing: heating, mechanical and chemical treatments. Heat treatment creates more bypass protein.
Forages – are processed to help diversify forage products. Main types of forage processing are alfalfa dehydration and hay compaction. These can result in forage products such as dehydrated alfalfa meal and pellets, sun-cured alfalfa pellets, alfalfa cubes, and compressed bales of timothy/alfalfa/mixed hay. These products are purchased and therefore not made on farm. Corn silage is another example of processed forage. It is processed to improve digestibilty and is produced on farm.
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