Handling Feeds (Processing, Mixing, Storage) 10 -8-12

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%

What are primary reasons for processing feed?

1. Alter physical form2. Alter particle size3. Prevent spoilage4. Improve palatability5. All of the above

Reasons to process feed

1. Alter physical form2. Alter particle size3. Prevent spoilage4. Isolate particular portion of plant5. Improve palatability6. Inactivate toxins or anti-nutritional factors7. Ease of handling8. 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

CrackingGrinding

SoakingHigh Moisture Grain Reconstitution

PoppingMicronizing

Steam rollingSteam flakingSoakingExtrusion (add pressure)Pelleting (add pressure)

Dry Wet

Cold

Ho

t

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 11.3Top. One type of a roller mill used forprocessing grain.

Right. The large corrugated rolls thatphysically 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.

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

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.

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

Corn soy diet

Avg. weight (g)

407 471 461

Feed/Gain 2.06 1.90 1.96

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

Forage : Concentrate

VFA, molar % 60:40 40:60 20:80

Acetate 66.9 62.9 56.7

Propionate 21.1 24.9 30.9

Butyrate 12.0 12.2 12.4

Methane, Mcal/d 3.1 2.6 1.8

Alfalfa Hay – Physical FormVFA, Molar, % Long Course grind Fine grind Pelleted

Acetate 62.5 56.8 47.5 18.2

Propionate 23.8 27.1 28.5 45.7

Butyrate 10.8 13.6 23.9 32.8

Diet Effects on VFA production

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, low-quality roughages produce performance in young cattle or lambs almost comparable to that yielded by high-grain feeding.

ROUGHAGE PROCESSING Pelleting

• 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.

• Long term feeding of finely ground, pelleted rations for long periods of time may be detrimental to the rumen. – Animals can 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 considerable advantage – stacking and storage

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 - form handled readily by mechanical equipment.– a more uniform product

– 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. – fat or molasses is sometimes sprayed on bales before they are

ground – reduce dust.

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 is typically more palatable for ruminants or horses

• However, chopped hay does not lend itself as well to incorporation into mixed feeds as does ground 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.

Impacts on Nutritive Value

NUTRITIVE VALUE - Grinding and Pelleting

• Grinding results in reduction in particle size and exposure of much more surface area – Increase in digestibility

• Storage of ground grains or other feedstuffs results in destruction of readily oxidized nutrients (fats, vitamins).– Unsaturated fats, especially in the presence

of trace minerals such as Fe and Mn.

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 useful.

• 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:

– Starch gelatinization: more efficient utilization of grains, particularly if mechanical rupture of starch granules takes place, especially for ruminants on high-grain diets.

– Slight improvement in protein utilization for ruminants.

– But little if any improvement for nonruminants.

• Any treatment that increases exposure to air, heat or light normally results in some deterioration of vitamins. – Fat-soluble vitamins, thiamin, pantothenic acid,

folic acid, and biotin are susceptible to destruction by heat and light.

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 themwith 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.