Handling Feeds
(Processing, Mixing, Storage)
10-8-12
FEED PROCESSING
• Feed cost is normally the single largest
expense associated with any animal
production operation
– > 50%
– Often up to 80%
Why Process Feeds?
1.
2.
3.
4.
5.
6.
Alter physical form
Alter particle size
Prevent spoilage
Isolate particular portion of plant
Improve palatability
Inactivate toxins or antinutritional
factors
7. Ease of handling
8. Increase digestibility
How does processing increase
digestibility?
• Improve intake
– How does this affect digestibility?
– How does this affect nutrient uptake?
• Increase surface area of particles
– More surface area for chemical and enzymatic
reactions
• Alters molecular structure
– Denaturing, cooking starch, etc…
How are feeds processed?
Grain Processing
• Cold or Hot Processing
– Cold
• Cracking, grinding, soaking, reconstitution, high
moisture grain, acid preservation
– Hot
• Steam rolling or flaking, pelleting, extrusion, popping,
micronizing, roasting
• Dry or Wet Processing
Grinding/Cracking – Cold Processing
• Various scales of grinding
– Hammer mill or Roller Mill
• Most common method
• Inexpensive
• Simple
Cracking & Grinding - Roller Mills
Act on grain by compressing it
between two corrugated rolls
that can be screwed together
to produce smaller and
smaller particles.
Figure 11.3
Top. One type of a roller mill used for
processing grain.
Right. The large corrugated rolls that
physically crush the grain as shown.
Courtesy of Automatic Equipment Mfg. Co.
Pender, NB.
Roller Mills
• Products can range in size
– cracked grain to a fine powder = corn, wheat, or
milo
– Flattened to powder = course grains (barley, oats)
• The hulls won’t grind into powder well with roller mills
• Roller mills produce a less dusty feed than a
hammer mill.
– If the grain is not ground too finely, the physical
texture is very acceptable to most species.
• Swine diets - very finely ground
– Roller mills are not used with roughage.
Hammer Mills
• Process feed using rotating metal
bars (hammers) that blow the ground product
through a metal screen.
– Particle size is controlled by changing the screen
size.
Figure 11.5
One example of a portable grinder
(hammer mill) and mixer available
for on-the-farm use.
Courtesy of Richard Kellems.
Grinding - Summary
• Grinding improves nutrient utilization by disrupting the outer
protective coating and increasing the accessibility of the digestive
secretion to the materials inside.
• Coursely ground grains are preferred for ruminants
– Not palatable when fine, or dusty
• Fine ground common for poultry and swine
• Grinding is comparable to other processing methods when intake of
grain is low.
Soaking Grain – Cold/Hot Method
• Grain soaked for 12 to 24 hours in water
• Soaking, (may also be heat), softens the grain, which
swells, making a palatable product that should be rolled
before use in finishing rations.
– Research does not show any marked improvement in
feed efficiency as compared to other processing.
• Space requirements, handling problems and potential
souring discourage large-scale use.
Reconstitution – Cold Method
• Reconstitution is somewhat similar to soaking.
– Water is added to mature, dry grain to raise the
moisture content to 25% to 30%.
– Stored in an oxygen-limiting silo for 14 to 21 days.
• Improved gain and feed conversion by beef cattle
fed high-concentrate rations when whole grain
used (milo and corn)
– Does not work well if grain is ground prior to
reconstitution. Milo should be rolled after.
– Some fermentation takes place during holding.
– Disadvantage is in regard to capacity and holding
High-Moisture Grain
• High-moisture grain refers to grain harvested at a high moisture
content ( 20 to 35%) & stored in a silo or under plastic to preserve the
grain.
• Can be further processed before or after ensiling.
– May be useful when weather doesn’t allow for drying in the field
• High-moisture grain produces good feedlot results, with feed
conversion particularly improved over dry grain.
– Disadvantages
• mold if weather is not cold, mishandled, or improperly stored,
not chemically treated.
• Storage costs may be high.
• More difficult to dispose of than dry grains
High-Moisture Grain –
Acid Preservation
• 1 – 1.5% addition propionic acid, mixtures
of acetic & propionic acid, or formic &
propionic acid
– Prevent mold and spoilage
– Won’t affect animal performance if mixed
correctly
Hot Processing Methods
• Methods for heat processing include:
– Common: Steam rolling and flaking;
extruding, pelleting
– Uncommon: Popping, micronizing, and
roasting.
• Some methods are time, equipment and
cost prohibitive
– Micronizing, popping, roasting
Popping, Micronizing, Roasting
• Popped corn is produced by action of dry
heat, causing a sudden expansion that
ruptures the endosperm of the grain.
– Increases gut and rumen starch utilization but
results in a low-density feed.
– Popped feed usually is rolled to reduce bulk.
• Micronizing is essentially the same as
popping, but heat is provided by infrared
energy.
Steam Rolling – Hot Process
• Steam rolling has been used since the 1940s, partly
to kill weed seeds.
• Steam passes up through a chamber that holds the
grain above a roller mill.
• Grains are subjected to 3- 5 minutes of steam
BEFORE being rolled.
• Does NOT modify the starch but it DOES soften the
seed.
• Less fines and larger flakes than dry/cold rolling –
typically improve animal performance
Steam Flaking Grains
• Steam-flaking, used since the 1960s
• Grains subjected to high-moisture steam
for 15 - 30 minutes.
– Rolled
– Feeding value can improve by 12% to 15%.
– The thinner the grain is flaked, the lighter the
bushel weight & faster the rate of in vitro starch
digestion.
Steam Flaking
• Steam flaking allows more efficient rupture of starch granules, for a
more desirable physical texture in the finished product.
• Starch becomes gelatinized – intermolecular bonds of starch break
down (water causes swelling) which allows hydrogen binding sites to
engage more water which dissolves the starch granules.
– Corn, barley & sorghum usually give a good response in terms of
increased gain & feed efficiency.
Extrusion
• Extruded grains or other feeds are prepared by passing the
feed through a machine with a spiral screw, forcing the feed
through a tapered head.
– Moisture is added
– Heat is added
– Pressure is added
– Starch is gelatinized
– Puffs and changes texture due to loss of heat and moisture at
the end of the process
– Dried but retains the porosity
http://www.youtube.com/watch?v=MU3PJb2Ngqs
HOT Pelleting
• Pellets, available commercially for over 50 years,
come in different diameters, lengths & hardness.
Figure 11.7 One type of pellet mill widely used for pelleting concentrates. A quick-change die is shown at the left.
Roughages can be pelleted, but production is reduced & costs are appreciably higher.
Pelleting
• Pelleting is accomplished by grinding feed and
forcing it through a thick, spinning die by rollers.
– Feedstuffs are usually steamed to some extent prior.
– Typically not enough to gelatinize the starch.
• Palatable
– High percentages of poultry, horse & swine feeds are
pelleted.
– Not as palatable for ruminants on high – grain diets.
Will see reduction in feed intake. Works well for
forages.
• Supplemental feeds such as protein concentrates
are often pelleted, so that they can then be fed on
the ground or in windy areas with much less loss.
Pelleting - Roughage
Advantages
• Pelleting roughages puts them in free flowing form
• Must be ground prior to pelleting – expense
• Reduce space requirement by as much as 75%
• May increase intake of forages
• Reduces dustiness
• Increase efficiency for low-quality forages
Disadvantages
• Cost of additional processing (more costly for
roughage than for concentrate)
• Reduces the roughage value of hay
• Examples of diet effects on VFA production
– Forage:Concentrate
VFA, Molar%
Acetate
Propionate
Butyrate
Methane, Mcal/d
60:40
66.9
21.1
12.0
Forage:Concentrate
40:60 20:80
62.9
56.7
24.9
30.9
12.2
12.4
3.1
2.6
1.8
– Physical form of forage
Alfalfa hay
VFA, Molar%
Acetate
Propionate
Butyrate
Grind
Long Coarse
62.5
56.8
23.8
27.1
10.8
13.6
Fine
47.5
28.5
23.9
Pelleted
18.2
45.7
32.8
Poultry - Pellets
• Typically fed crumbles rather than pellets
– More water consumption on pellets (10 – 20%)
– More cannibalism
• Crumbles are rolled pellets
Item
Mash
Crumble
Re-ground
Crumble
Avg. weight
(g)
407
471
461
Feed/Gain
2.06
1.90
1.96
Corn soy diet
ROUGHAGE PROCESSING
Pelleting
• Pelleting usually gives greatest relative
increase in performance for low-quality
roughages.
– Increased density, rapid passage through the GI
tract, and reduced digestibility is normal.
– Net nutrient uptake is increased because of the
increased consumption.
• Pelleted, high-quality roughages produce
performance in young cattle or lambs almost
comparable to that yielded by high-grain
feeding.
ROUGHAGE PROCESSING
Pelleting
• In ruminants, less cellulose is digested,
relatively less acetic acid is produced, and
relatively more digestion takes place in the
intestines.
– Because pellets pass out of the rumen more
rapidly.
• Feeding finely ground, pelleted rations for long
periods of time may be detrimental to the
rumen.
– Animals fed in this manner will develop
hyperkeratosis of the rumen papillae, which
reduces absorption and performance.
ROUGHAGE PROCESSING
Baled Roughage
• Baling is still one of the most common methods of
handling roughage, particularly where it is apt to
be sold or transported some distance.
Baling has a considerable
advantage over loose hay
stacked in the field, or in other,
less-dense forms.
Large bales are becoming more
common.
Figure 11.9 Unloading large bales of hay.
Baled Roughage
• Although handled mechanically for the
most part, it still requires more hand labor
than many other feedstuffs.
• Considerable waste may occur in feeding,
depending on how it is fed, and level of
feeding.
– Heavily fed animals such as dairy cows may
be quite selective, so that coarse stems will
not be consumed.
ROUGHAGE PROCESSING
Chopped and Ground Roughage
• Chopping or grinding puts roughage in a physical
form handled readily by mechanical equipment.
– Also tends to provide a more uniform product and
usually reduces feed refusal & waste.
– Many feed trucks are now able to chop hay in the
mixing chamber.
• Additional expense is incurred by grinding, and
loss of dust may be appreciable from grinding with
a hammer mill.
– To reduce dust loss, fat or molasses is sometimes
sprayed on bales before they are ground.
Figure 11.10 An example of a tub grinder, a type that is very useful for grinding roughages coarsely.
http://www.youtube.com/watch?v=HR9yFOnihdc&feature=related
• Ground hays are, as a rule, quite dusty
and may not be consumed readily.
– Adding moisture helps.
• Chopping produces a physical texture of a
more desirable nature for ruminants or
horses than does grinding.
– Chopped hay does not lend itself as well to
incorporation into mixed feeds as does
ground hay.
Figure 11.11 The effect of baling (left), grinding in a hammer mill (center), or grinding and pelleting (right)
on the volume of alfalfa hay after processing. Each pile contains 5 lb of hay.
ROUGHAGE PROCESSING
Dried, Dehydrated Roughages
• Alfalfa meal is produced in the U.S., mostly
for export, and some is produced in Europe.
• Dehydrated alfalfa, Bermuda grass, and other
forages are harvested at an early stage of
growth when protein content is high and the
fiber content relatively low.
– Also a high content of carotene and xanthophylls.
• Cost is relatively high, so it is used in limited
amounts for poultry or swine as a source of
carotene, vitamins, or unidentified growth
factors.
ROUGHAGE PROCESSING
Dried, Dehydrated Roughages
Figure 11.12 One example of a commercial dryer used for drying and dehydrating feeds.
EFFECT OF PROCESSING ON
NUTRITIVE VALUE - Heating
• Heat
– dry a feedstuff to a point allowing storage without
refrigeration, use of preservatives, or ensiling.
– Reduce microbial content (sterilization)
– Alter the chemistry (denature proteins, gelatinize
starch, inactivate toxins)
• With regard to proteins, excessive heating in the
presence of sugars may result in browning.
– As a consequence of the Maillard reaction, lysine
reacts with the sugars and becomes partially
unavailable to the animal.
NUTRITIVE VALUE - Heating
• Overheating fish or animal proteins makes them less
efficient.
• Heating of cereal grains to a moderate degree for
short periods of time may result in a slight
improvement in protein utilization for ruminants.
– But little if any improvement for nonruminants.
• Heating legume seeds results in an improvement in
protein quality, degrading anti-quality factors.
– Soybeans
• Increase the metabolizable energy value
• Reduces solubility of soy protein for less degradation of protein
in the rumen.
Nutritive Value - Heating
• In cereal grains, heat, especially with moisture,
results in partial gelatinization of the starch.
– More efficient utilization of grains, particularly if
mechanical rupture of starch granules takes place,
especially for ruminants on high-grain diets.
• Any treatment that increases exposure to air,
heat or light normally results in some
deterioration of most of the vitamins.
– Fat-soluble vitamins and thiamin, pantothenic acid,
folic acid, and biotin are particularly susceptible to
destruction by heat and light.
NUTRITIVE VALUE - Grinding and
Pelleting
• Grinding results in a substantial reduction in
particle size and exposure of much more
surface area to the action of chemicals, as well
as to the digestive juices.
• Storage of ground grains or other feedstuffs
results in destruction of readily oxidized
nutrients.
– Unsaturated fats, especially in the presence
of trace minerals such as iron and manganese.
• Digestibility of nutrients in pelleted feeds is
usually increased when retention time in the
digestive tract is the same.
HIGH-MOISTURE GRAIN
• Harvesting grains earlier may avoid losses to bad
weather or, in the case of sorghum grains, large
amounts of damage from birds.
– Early-harvested corn or sorghum may be expected
to have a moisture content of 25% to 30%.
– It is then necessary to dry, ensile, or treat them
with chemicals if the grains are to be stored.
– Early harvested grain requires less energy to grind or
roll, and are quite palatable to livestock.
– Protein & starch fractions are more soluble and more
completely digested, or digested at a more rapid rate
by ruminants.
Economics of Processing
• Relatively higher energy costs have increased
interest in minimizing feed processing costs or
obtaining maximum return per unit of cost for
processing or preservation.
Costs in megacalories of fossil
fuel (oil, coal, gas) per ton of
processed feed have been
estimated and are shown at
right.