How to Make Alfalfa Pellet in Europe
Alfalfa is widely grown throughout the world as forage for cattle, and is most often harvested as hay, but can also be made into silage, grazed, or fed as greenchop. Alfalfa usually has the highest feeding value of all common hay crops. In Europe, alfalfa cultivation and production is a main part of agriculture in countries like Spain, France, and Romania.
Spain is the second largest alfalfa producer in Europe. Alfalfa, like clover, is a cool-season perennial legume and can live from 3 to 12 years, depending on the variety and climate. The plant grows to a height of up to three feet and has a deep root system that can be as wide as 15 feet. Because of this extensive root system, alfalfa is fairly resistant to drought conditions.
The process of alfalfa pellet manufacturing was first developed for the livestock feed industry. It can be said to consist of a few basic sub-processes: grinding of alfalfa grass, drying, pelletizing, and cooling.
The raw alfalfa grass is first freed from heavy contaminants (rocks, metals, and other foreign materials), and then ground in a hammer mill or a chipping machine. The particle size is adjusted to a uniform maximum dimension, which is approximately 85 % or less of the minimum thickness of the pellet to be produced. The often high moisture content of raw alfalfa makes drying necessary. The product from the hammer mill is therefore transported to a dryer (generally a rotary drum type one) where the moisture content of the uniformly dimensioned particles is reduced to about 10 % (w.b.).
Then, alfalfa particles can be conditioned, i.e. steam or organic binding agents can be added (according to legal specifications). After conditioning, the particles are then moved by conveyor to a pellet mill, where the pellets are extruded through the action of rollers acting on a perforated matrix. On the outer side of the latter, a knife cut off the pellets at the desired length. Residual moisture in the feedstock turns to steam during compression and helps lubricate the compression die. After extrusion, alfalfa pellets are very hot (90-100°C) and are immediately air-quenched down to 25°C. This sets up the lignin and hardens the product, and contributes to maintaining its quality during storage and handling.
Finally, it is screened, so as to separate the residual fines which are generally re-used in the process. Dust-free alfalfa pellets are then ready for storage (in a silo) or for automatic packing (in 25 kg bags or big bags – 1 to 1,5 m³).
In the second step in alfalfa pellet processing, there are two main types of pellet presses: flat die and ring die types. The flat die alfalfa pellet mill has a circular perforated disk on which two or more rollers rotate and force the material through the holes. The ring die press features a rotating perforated ring on which rollers (normally two or three) press on the material to the inner perimeter.
The final processed alfalfa pellets can be used as animal feed, mainly horse feed. Using alfalfa products as forage for young horses is very beneficial because it is much more digestible compared to grass hays. Young horses do not have the ability to ferment fiber until they are about a year old. Feeding higher insoluble fiber forages such as timothy or orchard grass hay or poorer quality forage sources often results in “hay belly”. Therefore, feeding only highly digestible fiber such as alfalfa, clover, and beet pulp is recommended for the young growing horse.