Livestock Nutrition

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Livestock Nutrition

• Chapter 3
• Energy Nutrients

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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Sources of EnergyConcentrates

• 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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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Sources of Energy Byproducts

• These include the following
• Dried citrus pulp.
• Dried beet pulp.
• Potato meal.
• Dried sweet potatoes.
• Cotton seed hulls.
• Beet tops.

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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.

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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.

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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.

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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
  10-15 of the ration.

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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.

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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.

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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.

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Effects of Energy Deficiency

• 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.

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Effects of Energy Deficiency

• 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.

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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.