Livestock Nutrition

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Livestock Nutrition

• Feed Quality and Feed Analysis

Original Power Point Created by Dallas
Myers Modified by Georgia Agricultural Education
Curriculum Office June 2002
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Objectives

• Describe quality Characteristics of grains and
  other feeds.
• Describe methods of harvesting quality hay and
  silage.
• Describe the analysis of feedstuffs.
• Describe methods of measuring the value of feeds.
• Describe regulations relating to the manufacture
  and sale of feed stuffs.

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Feed Quality

• Quality of feed affects its value for animal
  nutrition.
• Quality factors include palatability and nutrient
  content.
• Improper harvesting or handling will reduce
  quality.
• Palatability refers to how well the animal will
  accept feed.

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Feed Quality

• If an animal does not find a feed palatable it
  will not eat enough, make good gains, grow
  properly or produce meat, milk or eggs.
• Feeds on produced on well fertilized soils will
  produce feed, especially roughages, that is of a
  higher quality.
• Vitamins, amino acid content and minerals will
  also be affected by soil type.

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Harvesting Hay for Quality

• Quality of hay is affected by harvesting and
  handling methods.
• Stemmy hay with fewer leaves is of lower quality,
  because the leaves contain the most nutrients and
  are the easiest digest.
• Shattering is the loss of leaves due to
  harvesting and handling.

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Harvesting Hay for Quality

• Legume hays will shatter easier than grass hays.
• Moisture content of hay must be reduced so it can
  be stored without spoiling or serious loss of
  nutrients.
• Field forages must not contain more than 18-22
  moisture for baling.
• Factors affecting moisture content include,
  humidity and movement of air, fineness of forage
  and how compact the bale is.

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Harvesting Quality Hay

• Shattering, leaching and bleaching are 3 things
  that cause loss of quality during harvesting.
• When forages get too dry, leaves tend to shatter.
• Forage that is rained on while curing will suffer
  loss of quality by leaching, (loss of water
  soluble nutrients.
• Bleaching occurs when the forage has cured to
  long in extremely hot temperatures.

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Harvesting Quality Hay

• Forages should be cut as soon as possible after
  reaching the early bloom stage of maturity.
• If hay is not conditioned it will require two
  days of drying before it is ready to bale.
• Conditioning breaks the stems, reducing the
  amount of time that it takes dry the hay.

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Harvesting Quality Hay

• Hay should be baled as soon as possible after it
  reaches a safe moisture level for storage.
• Delays in baling at this point will increase the
  chances of losing nutrients to bleaching and
  leaching.
• If small square bales are not stored under cover
  they will lose quality due to moisture, causing
  musty and moldy bales.
• Rain and snow can easily soak a small bale stack
  through and through

10
Producing Quality Silage

• When high moisture crops are stored under
  anaerobic, without air, conditions, a
  fermentation process occurs that produces silage.
• Crops may be stored is vertical or horizontal
  silos.
• Vertical silos require less land, less spoilage
  and require less labor for unloading.

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Vertical Silos

• Can be either conventional or gas tight.
• Conventional are constructed of concrete staves,
  metal, or cast in place concrete.
• At time of ensiling crop should contain 25-35
  moisture.
• If crop is to high or low in moisture, spoilage
  will be high.
• Gas tight silos are constructed to eliminate air,
  ensure preservation and storage of forages with a
  range of approximately 25-75 moisture.

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Horizontal Silos

• Trench, bunker and stack are the three types of
  horizontal silos.
• A trench silo is usually dug into the side of a
  hill, a concrete bottom is recommended due to mud
  and water.
• Filling is accomplished with dump trucks or
  wagons.
• After filling the pit is covered with a
  polyethylene sheet and weighted with dirt,
  concrete blocks or boards.

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Horizontal Silos

• Bunker silos are posts and boards with a side
  lining of building paper or plastic.
• Bunker silos are above ground, while pit or
  trench silos are below ground.
• Bunkers silos are usually made with a concrete
  floor as well.

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Horizontal Silos

• Stack silos require a small investment and may be
  used for emergency storage of surplus silage.
• Silage is spread in shallow layers using
  tractors, the sides should slope 60 degrees.
• During filling the silage is packed with a
  tractor.
• When filling is completed, the top of the stack
  is rounded off, black plastic 4-6 mil thick, is
  used to cover the stack.
• The slack should be always taken out of the
  plastic with the weights on the side.

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Physiological Changes in Silo

• The most commonly used silages are corn and
  sorghum.
• Crop should be at 62-68 moisture before
  ensiling.
• If crop is too wet it will not produce lactic
  acid but butyric acid, causing a sour feed with
  high nutrient loss.
• If it is too dry it will mold easily.

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Physiological changes

• It takes about 21 days for the fermentation
  process to complete.
• Living cells continue to burn plant sugars, use
  oxygen, and give off carbon dioxide, water and
  heat.
• Acetic acid is produced early in the process and
  plant pH changes from 6.0 to 4.2.
• After 3 days, the formation of acetic acid slows
  down and lactic acid is formed.

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Physiological changes

• Formation of lactic acid continues for about
  another 2 weeks and the temp decreases.
• Bacterial action stops when pH reaches 4.
• If conditions are have been right, the silage is
  now fairly stable, and will remain so for a long
  period of time.
• The ideal temp is 80-100 degrees, if temp is
  lower butyric acid is formed, causing foul odor
  and breaking down the protein.
• Higher temps cause caramelized silage is formed,
  it is sweet tobacco smelling, it is higher is
  palatability but low in nutrient value

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Harvesting Crops for Silage

• Corn should be harvested at the dough to hard
  dent stage, 32-38 moisture.
• Grasses and legumes should be wilted to below 65
  moisture.
• Grasses should be ensiled in the early heading
  stage and legumes at about one tenth bloom.
• Small grains are harvested for silage in the boot
  to early milk stage for best results.

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Silages

• Grass and Legumes should be chopped at one
  quarter inch.
• Dry matter losses are kept to a minimum when
  grasses and legumes are stored in the silo at
  50-65.

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Adding Dry Matter and Preservatives

• Many things are added to silages to reduce
  moisture, aid in curing and increase
  palatability.
• Dry grain, is added to reduce moisture, however
  it may not be economically feasible.
• Chemicals increase palatability but also may not
  be financially feasible.

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Important other Factors

• Rapid filling, even distribution, packing and
  prompt covering of silages.
• Legumes that are higher in protein will spoil
  quicker.
• Grass silage does not keep well in trench or
  bunker silos.
• Corn silage should be chopped to 1/4 -3/8 of an
  inch.
• Corn should be filled quickly and evenly.

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Feed Samples for Analysis

• Sample must be carefully secured to accurately
  represent a much larger quantity of feed.
• Less than one quart of feed is usually submitted.
• There are many was to sample, hand, harvest, core
  and bulk feed. Moisture content should always be
  consistent as possible.

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Proximate Analysis of Feedstuffs

• Feed using chemical and mechanical means is
  separated into 6 components.
• Water content, crude protein with Kjeldahl
  process, crude fat, crude fiber, minerals, and
  Nitrogen free extract.

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Limitation of Proximate

• No indication of palatability, digestibility,
  toxicity or nutritional value.
• Feeding trials with live animals are necessary to
  determine actual worth of a feed for practical
  feeding purposes.
• Organic components of the feed, crude proteins,
  amino acids, ether extract and cell wall may vary
  in individual fees as much as 15 more or less
  than the table values.

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Feed Composition Basis

• All feeds contain moisture, depending upon the
  form fed, time harvested and storage time.
• As fed means the data is calculated on the basis
  of the average amount of moisture found in the
  feed as it is used on the ranch.
• 100 dry matter basis means that the data
  presented is calculated on the basis of all the
  moisture removed from the feed.

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Van Soest Method

• Neutral detergent soluble is lipids, sugars,
  starches and proteins.
• Neutral detergent fiber is the more insoluble
  material found in the cell wall.
• Consists of cellulose, lignin, silica,
  hemicellulose and some protein.
• Acid detergent fiber consists of cellulose,
  lignin and some silica.