Transcript Livestock Nutrition

Livestock Nutrition
Chapter 3
Energy Nutrients
Objectives
Define terms of associated with energy.
Describe the energy nutrients.
List sources of energy nutrients.
Describe the functions of energy nutrients.
Describe symptoms of deficiencies of
energy in the ration.
Terminology
• Calorie, (cal)- the
amount of heat energy
required to raise the
temperature of one
gram of water form
one degree C3.
• Kilocalorie, 1,000
calories.
• Mega calorie,
1,000,000 calories.
Terminology
• Gross Energy (GE)- the total amount of heat
released when a substance is completely oxidized
in a bomb calorimeter.
• Digestible Energy (DE)- The gross energy of feed
consumed minus the gross energy excreted in the
feces.
• Metabolizable Energy (ME)- The gross energy of
the feed minus the energy in the feces, urine, and
gaseous product of digestion.
Terminology
• Heat Increment (HI)- that portion of the ME
which is used for digestion or metabolism
of absorbed nutrients into body tissue.
• Net Energy, (NE)- the metabolizable energy
minus the heat increment. Used for growth,
maintenance, production, work, fetal
development and heat production.
Energy Nutrients
• Carbohydrates and lipids ( fats and oils) are the
major sources of energy in livestock rations.
• Carbohydrates are the most important because
they are readily available, easily digested & lower
in cost.
• Proteins are seldom fed for their energy content
because of the higher cost of this source.
Carbohydrates
• Organic compounds made of carbon,( C ),
Hydrogen (H), & Oxygen (O).
• Each C2H2O molecule is made up of 40% C, 7%
H and 53% O2.
• Carbohydrates found in plants include starch,
sugars, hemicellulose, cellulose, pectin's, gums, &
lignin.Sugars are the most easily digested while
cellulose and lignin are more difficult.
• Carbohydrates in the feed are changed to simpler
forms.
Carbohydrates
• 75% of all the dry matter in plants is
carbohydrates.
• More easily digested forms of carbohydrates are
generally found stored in the seeds, roots and
tubers of the plant.
• Hemicellulose and cellulose are converted to
glucose.
• Because hemicellulose and cellulose require more
energy, they are less efficient sources of energy for
the animal.
Carbohydrates
• Carbohydrates are divided into two groups,
FIBER & NITROGEN-FREE EXTRACT.
• Fiber because of the lignin, cellulose and
hemicellulose it is less of an efficient feed
than NFE.
• The NFE group includes sugar, starch and
some hemicelluloses.
Carbohydrates
• Starch is made up of many molecules of glucose.
• Grains have a high feeding value because the
starch is easily digested.
• Ruminant animals because of bacterial action in
the Rumen can utilize large portions of coarse
roughage.
• Non-ruminants have less ability to utilize energy
from fiber.
• The young of all species require more easily
digested feeds.
Lipids (fats & oils)
• Lipids are 77% C, 12% H & 11% O.
• Because there is more carbon and hydrogen
and less oxygen in the molecule, lipids
supply approximately 2.25 times as much
energy as an equal weight of carbohydrates.
• Lipids are classified as simple, compound
and derived.
• Simple lipids are true fat and waxes.
Lipids
• Compound lipids are esters, which contain groups
in addition to an alcohol and fatty acid.
• Derived lipids are from simple or compound
lipids, separated by hydrolysis.
• Fatty acids are either saturated or unsaturated.
• Fats are used to raise the energy level of the diet
and/or improve the flavor, texture and palatability
of the feed.
• Rations for adult ruminant animals should contain
no more than 3-5% fat and 15-20% fat for
nonruminants.
Sources of Energy
Concentrates
• A major source of energy nutrients is the
grains and grain byproduct.
• These feeds are called energy concentrates
or basal feeds when their crude protein is
less than 18% in the air-dry state.
Shelled Corn
• One of the highest energy feeds available.
• The most widely grown and used feed grain crop.
• Corn produces more #’s of TDN/acre than any
other.
• It is an economical and superior source of energy.
• Consideration must be given to amount to feed,
frequency and combinations with other feeds, in
order to get the most efficient use of this high
energy feed source without causing digestive
problems.
Corn & Cob Meal
• Contains about 10% less energy than
shelled corn because of the fiber content in
the cob.
• All species can utilize it, however, when
feed to growing-fattening hogs because they
do not have the ability to digest and use
much of the cob content.
Ground Snapped Corn
• Made up of the grain, cob and shucks and is
considerably higher in fiber and lower in
TDN than shelled corn.
• Comparable to oats.
• Very seldom used because of the high labor
requirement in harvesting it.
Corn Starch and Corn Oil
• Fairly pure forms of starch and oil.
• Generally not used in commercial
enterprises however, they are sometimes
used in the purified diets of experimental
animals.
Oats
• About 85% of the energy of shelled corn.
• Higher in crude protein than shelled corn and add
fiber and bulk to the ration.
• Help the rumen maintain bacterial and protozoa
function.
• Not a good fattening feed but are used extensively
in rations for horses, young growing stock, show
stock and breeding animals.
• Usually fed rolled, crimped or ground.
Barley
• Almost equal to corn in energy value, but lies
between corn and oats in fiber content.
• Used in a ration in a manner similar to oats.
• Barley may replace up to 50 % of the corn in
rations for fattening animals.
• The grain content of the ration may be decreased
by 10 % if barley replaces all of the corn.
• To improve palatability it is usually steam rolled,
crimped or coarsely ground.
Wheat
• High in both energy and protein it is generally not
used in livestock rations because of the high value
as a small grain crop on the cash market.
• Wheat is similar to corn in composition and
feeding value.
• If and when it is used in a ration it is included at
low levels in a mix with other grains because it is
rapidly digested and may cause digestive
disturbances.
Grain Sorghum
• There are many varieties, milo, kafir and
various hybrids.
• Smaller than shelled corn and may replace
up to 100% of the corn in a feedlot ration.
• Generally rolled or ground when included
in a ration.
Rye
• Rye is usually used for bread for human
consumption and has limited use as a livestock
feed.
• It is not as valuable as corn, whet or grain
sorghum.
• Ergot contaminated rye can be toxic to livestock.
• The use of rye in livestock rations should be
limited to no more than one-third of the ration.
• It should be coarsely ground or rolled to increase
palatability.
Sources of Energy
• Forages (roughages) can supply some of the
energy needs in the livestock ration, although they
are not as concentrated a source of energy as the
grains.
• Value of forages for livestock feed is highly
dependent on time of harvesting.
• As forage plants mature, the crude fiber content
(cellulose and lignin) increases, which lowers the
digestibility of the feed.
• When forages are harvested as silage, more of the
nutritional value of the plant is preserved.
Corn Silage
• Corn silage, which contains almost 50%
grain on a dry matter basis, is an excellent
energy source for certain classes of
livestock.
• Sorghum and small grain silages are lower
in energy content than corn silage.
Straws
• Oat, barley and wheat are low in energy
value and are not used as a major source of
energy.
• It may be used if additional fiber is needed
in the ration.
Pastures
• Properly managed pastures can be a good
source of nutrients.
• Rotating and fertilizing pastures to get the
best yield and nutritional value.
• Quality of pasture must be closely watched
and supplemented with good quality stored
forages when necessary.
Sources of Energy Byproducts
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These include the following:
Dried citrus pulp.
Dried beet pulp.
Potato meal.
Dried sweet potatoes.
Cotton seed hulls.
Beet tops.
Dried Citrus Pulp
• The remaining pulp, after the fruit is
removed, can also come from cull fruit.
• Can be fed dried or wet.
• High in fiber content but it is considered an
energy feed.
• It usually limited to not more than 20-25%
of the ration.
Dried Beet Pulp
• Primarily used in dairy cattle rations but is
occasionally used in rations for horse, beef
and sheep.
• Adds bulk to rations.
• Makes rations more palatable, mild laxative.
• Should not replace more than 20% of the
grain in a ration.
Sources of Energy---Fats
• A byproduct of packing plants, and poultry
processing plants.
• Commercial feed mixes will contain 1-7% animal
fat.
• Animal fat in the feed reduces the dustiness of the
feed.
• Often treated with antioxidants to prevent the feed
from becoming rancid in storage.
• Beef and dairy rations can contain up to 5% while
swine rations may have up to 20%.
Sources of Energy---Molasses
• Common types of molasses are cane or blackstrap,
beet, citrus and wood.
• Molasses is used in rations for cattle, sheep and
horses but is seldom used in swine rations,
because it causes scouring.
• Improves palatability, aids rumen microbial
activity, reduces dust and serves as a binder when
feeds are pelleted.
• Molasses is usually limited to not more than 1015% of the ration.
Functions of Energy
• Energy nutrients are needed for the maintenance
of life in the animal.
• Maintains basal metabolism.
• Basal metabolism is defined as the heat production
of the animal while it is at rest and not digesting
food.
• Beating of the heart, maintenance of blood
pressure, transmission of nerve impulses,
breathing and work of other internal organs.
Functions of Energy
• When animals are on full feed they seldom reach
lower critical temperature unless the weather is
extremely cold.
• It is only after all the maintenance needs of the
animals are met that energy nutrients can be used
for growth or production.
• Fattening livestock requires a large amount of
energy nutrients.
• Energy not used for other needs is deposited as
fats within the body tissues.
• The deposition of fats makes the meat tender,juicy
and gives it a better flavor.
Functions of Energy
• When feeding horses, the amount of energy
needed for no body weight change and the normal
activities of the nonworking horse is called the
maintenance requirement.
• A number of factors affect the amount of energy
needed, intensity and duration of work, condition
and training of the horse, the ability and weight of
the rider, degree of fatigue of the horse and
environmental conditions in which he is
performing.
Effects of Energy Deficiency
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Slow growth of young.
A delay in the onset of puberty.
A decrease in milk yield in lactating females.
A shortened lactation period.
A Los in body weight.
Several kinds of reproductive problems including
reduced fertility and delayed estrus.
Effects of Energy Deficiency
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In sheep, a reduction in wool quantity and quality.
A higher mortality rate.
A lowered resistance to disease.
Weakness, generally poor condition, and unthrifty
appearance.
• Hypoglycemia.
• A loss of subcutaneous fat.
• A reduction in levels of blood glucose, calcium,
and sodium.
Do the Following Review
Questions
• Numbers 1, 2, 3, 5, 6, 8, 9, 10, 11, 12, 14,
18, 19, 20, 22, 23, 24, 25, 27, 28, 29, 30.