DAIRY FEEDS AND FEEDING

1
DAIRY FEEDS AND FEEDING

• PROXIMATE ANALYSIS OF FEEDSTUFFS

2
I. Proximate Analysis

• A. Developed over 100 years ago at the Weende
  Experiment Station in Germany.
• B. It is a system for approximating the value of
  a product for feeding purposes, without actually
  using it in a feeding trial.
• C. It is based on the separation of a sample of
  a feed into nutritive fractions through a series
  of chemical tests which will reflect the feeds
  feeding value.

3
D. The different fractions are

• 1. Water (Moisture)
• 2. Crude Protein
• 3. Crude Fat (Ether Extract)
• 4. Crude Fiber
• 5. Nitrogen-Free-Extract
• 6. Mineral Matter (Ash)

4
II. Procedures of Proximate Analysis

• A. Obtaining a sample to Test
• 1. Collect a small amount from several locations
  within a lot of feed.
• 2. Finely grind or chop the sample and mix it
  thoroughly.
• 3. Keep sample pure.

5
B. Testing Procedures

• 1. Water or Moisture
• a. Weigh a small amount of the sample.
• b. Dry in an oven until there is no further loss
  in weight.
• 1) Approximately 2 hours at 135O C for air dry
  samples
• 2) At 1000 C for approximately 8-24 hours
• 3) Today it is possible to use a Microwave oven
  for a much shorter period of time.
• c. Weigh sample again after drying.
• d. To calculate percentage of water/dry matter
• 1) Water (Moisture)
• Loss of Weight during Drying X 100 Water
• Weight of Sample before Drying
• 2) Dry Matter
• Weight of Sample after Drying X 100 Dry
  Matter
• Weight of Sample before Drying

6

• 2. Crude protein
• a. Determined by a process called Kjeldahl.
• b. This process actually determines the amount
  of Nitrogen (N) that is in a sample of feed which
  is then converted to an approximate Protein
  percentage.
• c. Most proteins contain approximately 16 N,
  with a range of 15 - 18 N.
• d. Called Crude Protein because a small amount
  of the Nitrogen in the sample may come from
• 1) Non Protein Amino Acids
• 2) Certain Vitamins
• 3) Urea
• 4) Biuret
• 5) Ammonia

7

• e. Procedure
• 1) Weigh out a small quantity of the feed sample
• 2) Determine the amount of Nitrogen in the
  sample through a chemical process. (sulfuric acid
  digestion)
• 3) Calculate the amount of protein in the sample
  by multiplying the amount of nitrogen by 6.25
  (since protein is 16 N, 6.25 times the amount of
  N in the sample would equal the total amount or
  100 of the protein in the sample).
• 4) Calculate the percentage of crude protein in
  the feed
• Amount of Protein in Sample X 100 Crude
  Protein
• Weight of Sample

8

• 3. Crude Fat (Ether Extract)
• a. Includes that portion of a feed sample that
  is soluble in ether.
• b. Called Crude Fat because an Ether Extracted
  sample may also include
• 1) Fat-Soluble Vitamins
• 2) Carotene
• 3) Chlorophyll
• 4) Oils
• 5) Pigments
• 6) Waxes
• 7) Resins
• c. Procedure
• 1) Weigh out a small quantity (sample.
• 2) Dry the Sample. (Same procedure as for
  Moisture determination)
• 3) Extract the sample with ether in a Soxhlet
  extractor for 4 hours.
• 4) Evaporate the ether from the extract and
  weigh what remains.
• 5) Calculate the Percentage of Crude Fat
• Weight of Crude Fat X 100 Crude Fat
• Weight of Sample

9

• 4. Crude Fiber
• a. This process will determine how much fibrous
  material is in a sample and should include
• 1) Hemicelluloses
• 2) Cellulose
• 3) Lignin
• b.Steps to determine Crude Fiber
• 1) Weigh out a small sample (
• 2) Oven Dry Sample
• 3) Extract the Sample with Ether to remove Crude
  Fat
• 4) Boil the remainder of the sample in dilute
  sulfuric acid for 30 minutes, and filter then
  boil in dilute sodium hydroxide for 30 minutes,
  and filter.
• This process will remove the proteins, sugars,
  starches, and more soluble hemicelluloses and
  minerals and also possibly some of the lignin, if
  present.
• 5) Dry the residue and weigh. This residue will
  consist of the Crude Fiber and the more insoluble
  mineral matter.
• 6) Ash (Burn) the residue to oxidize off the
  Crude Fiber and weigh the ash.
• 7) Calculate the amount of Crude Fiber in the
  sample by subtracting the weight of the ash in
  step 6 from the weight of the residue in step 5.
• 8. Calculate the Percentage of Crude Fiber as
  follows
• Weight of Crude Fiber X 100 Crude
  Fiber
• Weight of Original Sample

10

• 5. Mineral Matter (Ash)
• a. This process will determine the total amount
  of Mineral Matter present in a sample, not each
  individual Mineral.
• b. Procedure
• 1) Weigh out a small quantity of the sample into
  a crucible
• 2) Ash (Burn) in a furnace at red heat (6000 C)
  for several hours.
• 3) Weigh the Ash, which includes the minerals in
  the sample.
• 4) Calculate the percentage of Ash or Mineral
  Matter
• Weight of the Ash X 100 of Ash
• Weight of Sample

11

• 6. Nitrogen-Free Extract
• a. Includes mostly Sugars and Starches and some
  of the more soluble Hemicelluloses and more
  soluble lignin.
• b. NFE is determined by difference
• Water (Moisture)
• Crude Protein
• Crude Fat
• Crude Fiber
• Mineral Matter
• 1000 - (Total of Above s) Nitrogen-Free
  Extract

12

• 7. Vitamins
• a. The amount of Vitamins is not determined as a
  part of Proximate Analysis.

13
III. Ways of Expressing Compositions

• A. Percentage () Parts/Hundred Parts
• B. Parts Per Million
• 1. This just means that a feed contains so many
  parts of a certain component per 1,000,000 parts
  of that feed.
• 2. To convert to PPM simply move the decimal
  point four places to the right.
• Example 1.5 15,000 PPM
• 3. To convert PPM to simply move the decimal
  point four places to the left.
• Example 30,000 PPM 3

14
C. Milligrams per Kilogram (mg/kg)

• 1. This is basically the same as PPM since a
  Kilogram is equal to 1,000,000 Milligrams.
• 2. This is PPM in Metric

15
D. Milligrams per Pound (mg/lb.)

• 1. A pound equals 453,000 milligrams.
• 2. 453,000 will go into 1,000,000 2.202 times.
• 3. To change mg/lb., to PPM multiply by 2.202.
• 4. To change mg/lb., to multiply by 2.202 and
  divide by 10,000.\
• 5. To change PPM to mg/lb., divide by 2.202.
• 6. To change to mg/lb., multiply by 10,000 and
  divide by 2.202.

16
IV. Composition of feeds may be based on

• A. As Fed Basis or Fresh basis refers to feeds
  as they are actually fed.
• B. Air-Dry Basis Generally based on a 90 Dry
  Matter
• C. Oven-Dry Basis Based on a 100 moisture
  free basis (Completely Dry)

17
D. The different Bases

• As Fed Air-Dry Oven-Dry
• Water May be any Usually 10 0
• Crude Protein This is dry
• Crude Fat matter it
• Crude Fiber is always Usually 90 100
• NFE 100 minus
• Ash the water

18
E. Converting of one basis to another can be
accomplished through the use of ratios.

• of any component in a feed of the component
  in the
• on any basis feed on another basis
• DM in that feed on the same of DM in the
  feed on the
• basis same basis
• Example If a feed contains 5 crude protein on
  a fresh basis and 80 water, the percentage of
  crude protein on an air-dry basis would be
  calculated as follows

19
Air-Dry Basis

• 100 - 80 20 DM in the fresh feed
• 5 X
• 20 90
• 20X 5x90
• 20X 450
• X 450/20
• X 22.5 Crude Protein on an Air Dry Basis

20
Dry Basis

• 5 X
• 20 100
• 20X 5x100
• 20X 500
• X 500/20
• X 25 Crude Protein on a Dry Basis

21
THE END