Feed Processing Flashcards
Feedstuff processing methods fit into two categories:
Thermal
Non Thermal
The primary non-thermal method of processing feedstuffs involves particle size _____ or _____
reduction or grinding
Grinding may be performed on _______ (pre-grinding) or on __________ (post-ingredients).
_______ is most commonly used in the feed industry
raw ingredients or mixtures of raw ingredients
pre-grinding
Advantages of grinding
- ground feedstuffs have an increased exposed surface area for attachments by microbes and enzymes
- ground feedstuffs have improved mixing characteristics, and mixes of ground grains are less likely to separate during handling
- grinding of the grain mix is essential for successful pelleting
Grinding is affected through….
compression, impact, attrition, and shearing (cutting or tearing)
There are 2 basic types of equipment that are used to grind
hammer mill and roller mill
hammer mill
grain is added to a feeder that drops grain over spinning hammers that are traveling in excess of 16,000 ft./min. When the hammer strikes the grain, it shatters, producing a variety of particle sizes. Grain particles of small enough size pass through the screen around the hammers
primary advantage of the hammer mill over the roller mill
output has more tons per hour can be ground using a hammer mill
primary disadvantage of the hammer mill
difficulty in producing a product of uniform particle size
roller mill
grain is added to a feeder that drops grain onto rotating cylinders or rollers. different outcomes can be achieved by varying the distance between the rollers, adjusting the speed differential between the rotating rollers, using grooved rollers, and exposing grain to steam before rolling
primary advantage of the roller mill over the hammer mill
product appears as roller mills produce a ground product of uniform particle size that can be used to crimp, crack, crumble and flake feed
primary disadvantage of the roller mill
output as fewer tons per hour can be ground using a roller mill compared with a hammer mill
thermal processing methods include:
- popping and micronizing
- steam rolling and flaking
- roasting
- extruding and expanding
- pelleting
because heat treatment can enhance starch digestion, grain for horses, dogs, cats, rabbits and fish is nearly always processed using….
one or more types of thermal processing
Popping and micronizing
involve rupturing the endosperm of the grain by heating the grain (using dry heat or infrared energy) until the moisture within it vaporizes. Because the water occupies more space than the liquid, the grain explodes or pops
-Fairly uncommon due to expenses
When popped grain is fed to livestock…
there is an increase in starch utilization compared with whole grain
Problems with popping and micronizing
- individual kernels of popped grain occupies much more space than the unpopped kernels and this presents a problem in handling and storage
- there are less expensive methods of processing that obtain similar improvements in starch utilization
Steam Rolling and Steam Flaking
both processes contain heat and moisture, and involve exposing grain to steam prior to passing through the rotating cylinders of a roller mill.
In steam rolling, exposure to steam is of ______ duration, whereas in steam flaking the exposure to steam is _______.
short
long
Roasting
a process that is most commonly applied to whole soybeans. For ruminant animals, soybeans are roasted to alter the ruminant undegradable fraction of the protein.
Extruding and expanding
machines that expose ground feed to moisture, high pressure and high temperature. In both types of machines, ground feed is conveyed through a barrel in which it is exposed to steam and the forces of shearing and pressure.
Various changes can occur during this process such as starch and protein gelatinization
Starch gelatinization
the crystalline structure of the starch granules is destroyed and the starch becomes an amorphus blob
Starch gelatinization is desirable because…
this is desirable because, feed containing gelatinized starch can be shaped and expanded
Gelatinized starch enhances the ability to absorb large quantities of water, which frequently leads to improved digestibility and feed conversion by the animal
Protein gelatinization results in denaturation of the protein which can result in…
- improved protein digestibility
- destruction of some amino acids
heat and pressure generated during extruding and expanding….
- can change feed proteins so that they will be more resistant to microbial degradation in the rumen
- will reduce or eliminate toxins, insect and microbes in the feed
- will destroy some vitamins and feed additives
Pelleting
the most common type of feed processing equipment at feed mills. The pellet mill consists of a conditioner in which the mixed feed is exposed to steam (heat and moisture) and machinery that forces the material leaving the conditioner through the holes in a pellet die.
Advantages of pellets over mash:
Feed Handling Characteristics
- increased bulk density, more tons of pelleted feed can fit into a given space
- improved flow characteristics
- reduced dustiness
- decreased ingredient segregation during handling
Advantages of pellets over mash:
Animal Performance Characteristics
- decreased feed waste, probably due to the fact that pellets are more prehensile than mash
- reduced selective feeding
- destruction of insects and pathogenic organisms
- thermal modification of starch and protein
- improved feed acceptability / palatability
Disadvantages of pellets over mash
- Cost - pellet mills are expensive and feed mills charge $10 - $14 more per ton to run mixed feed through the pellet mill
- reduced feed output by the mill. More tons of feed could be manufactured in a day if all feeds were sold as mash rather than pellets
- nutrient destruction, although not as extreme as with extruding and expanding
- because of additional cost, pellet buyers expect high quality pellets (pellet durability or integrity)
