1. RUMINANT DIGESTIVE TRACT

2. Stomach Small intestine Large intestine Reticulum, rumen & omasum
Fermentation
Absorption of fermentation endproducts
Abomasum
Secretion of hydrochloric acid and pepsinogen
Small intestine
Similar to non-ruminant
No sucrase
Large intestine
More important in browsing species

3. CARBOHYDRATE DIGESTION IN RUMINANTS
Starch
Structural CHO
Methane Undegraded Small intestine
(Digestion similar to NR)
Fermented
Volatile fatty acids (VFA)
Liver & peripheral tissues
Energy and fat synthesis

4. PROTEIN DIGESTION IN RUMINANTS
True protein
NPN
Undegraded Small intestine
Metabolizable
Degraded protein
Recycled via
saliva
(20% of dietary N) NH Microbial
protein
NH3
Liver
Urea Kidney Excreted

5. LIPID DIGESTION IN RUMINANTS
Fat
Undegraded Small intestine
(Digestion similar to NR)
Degraded
Glycerol
VFA Long chain FA Saturated FA
Liver & peripheral tissues
Energy and fat synthesis

6. What is the primary volatile fatty acid produced in the rumen fed a high forage diet?
Acetic acid
Butyric acid
Lactic acid
Conjugated linoleic acid
Propionic acid

7. CHEMICAL ANALYSIS OF FEEDSTUFFS Pages 87-93

8. FEED ANALYSIS SYSTEMS Feed analysis systems
Needed to rationally group feed nutrients and requirements
Makes analysis relatively easy and cost-effective
Feed analysis systems
Proximate analysis system (Weende system)
Developed in 1864 at Weende Experiment Station in Germany
Detergent analysis system (Van Soest system)
Developed in 1964 at USDA Beltsville Research Center

9. PROXIMATE ANALYSIS COMPONENTS
Dry matter (DM)
Ash
Crude protein (CP)
Ether extract (EE)
Crude fiber (CF)
Nitrogen-free extract (NFE)

10. FEED NUTRIENTS

11. Dry matter (DM) DM,% = wt after drying/wt before drying x 100
% moisture = 100 – DM,%
Example
Ending weight = 550 grams
Beginning weight = 750 grams
What is the % Dry Matter?
What is the % Moisture (water)?
73.3% Dry matter
26.7% Moisture (water)

12. Problems with the DM method
Errors from losses of volatile components
Major issue for fermented feeds
Toluene distillation or freeze drying
Drying at 100o C destroys some nutrients and sample for further analysis
Freeze drying
Dry at lower temp for longer time for sample needing further analysis (will still need to run DM on portion of sample)

13. Significance of Dry Matter
Considerable variation in the DM, % of feedstuffs
Corn grain, 88% DM
Alfalfa hay, 90% DM
Alfalfa silage, 45% DM
Alfalfa pasture, 26% DM
Whey, 7%
Other nutrients are present within the dry matter
Affects expression of concentrations of nutrients in feedstuffs
Example Crude protein, %
DM,% Wet basis DM basis
Dried distillers grains
Modified distillers grains
Wet distillers grain

14. Significance of Dry Matter
Affects storage properties of feedstuffs
DM,%
<30
30-60
60-75
68-75
>82
Putrefaction
Ensiled forages
Mold & heating
High moisture grains
Dry grains and baled forages

15. FEED NUTRIENTS
Ash

16. Ash
Material remaining after oxidation of a sample in a muffle furnace.
% Ash = wt after ashing/sample wt x 100%
% Organic matter = % ash
Problems
No indication of amounts of individual minerals
Some minerals (Sulfur, Selenium, Zinc, Iodine are lost)
Significance
May indicate soil contamination or adulteration of feedstuff or diet.

17. What is in organic matter?
Nitrogenous compounds
Protein
Fat soluble vitamins
Starch
All of the above
None of the above

18. FEED NUTRIENTS
Organic Matter

19. FEED NUTRIENTS
Crude Protein

20. Crude protein (CP) Measures the nitrogen in a sample
Kjeldahl N – acid base titration
N analyzer – combustion, measures nitrogen
% Crude protein = %N x 6.25
What is % N?
Most proteins contain 16% N; therefore every 100 mg of protein contains 16 mg nitrogen.
100 mg protein / 16 mg nitrogen = 6.25
CP,% = measured mg N/100 mg sample x 100 mg protein/16 mg N
= measured mg N/100 mg/sample x 6.25

21. Question
Why have some foreign feed companies added the compound to some feed ingredients?
Increase the energy concentration
Increase the crude protein concentration
Supply an essential amino acid
Supply a required vitamin

22. Problems with crude protein procedure – will not indicate protein quality, source of nitrogen, digestibility
Sources of N:
True protein
Chains of amino acids bound by peptide linkages
Can meet the protein requirements of either non-ruminant or ruminant animals
Non-protein nitrogen
Forms
Free amino acids
Nucleic acids
Ammonia
Urea
Biuret

23. What form(s) of crude protein can be used to meet the crude protein requirement of a 120 lb growing gilt?
Chains of amino acids
Ammonia
Biuret
Urea
All of the above

24. What form(s) of crude protein can be used to meet the crude protein requirement of a 800 lb growing steer?
Chains of amino acids
Ammonia
Biuret
Urea
All of the above

25. Crude protein says nothing about the digestibility of a protein
Example:
% Crude protein % Protein Digestibility
Soybean meal
Feather meal

26. Heat Damage of Proteins
When overheated (heat damaged)
protein will bind to cell wall carbohydrates particularly across lysine
Reasons for this:
Molding of forages
Over-heating during processing
Over-drying of grains or soybeans
Referred to as the Maillard or Browning Reaction
Results
% Crude protein % Protein Digestibility
Well-preserved alfalfa hay
Heat-damaged alfalfa hay

27. FEED NUTRIENTS
Ether Extract

28. Ether extract (EE)
Reflux ether through sample (solvent pulls lipid out)
% EE = (Sample wt-residue after reflux)/Sample wt) x 100%
Also called crude fat
Problem with procedure
Ether extract consists of:
True lipids
Fats and oils
Non-nutritional ether soluble components
Fat-soluble vitamins
Chlorophyll
Pigments
Volatile oils
Waxes

29. FEED NUTRIENTS
Crude Fiber

30. Crude fiber (CF)
Extract with dilute acid, then dilute base, the residue weighed then ashed.
% CF = (residue wt - Ash wt)/sample wt x 100%
Theoretically represents:
the structural carbohydrates (Cellulose and hemicellulose)
Limited digestibility in ruminants
Poor digestibility in non ruminants
Lignin
Indigestible by ruminants and non ruminants
Problems with procedure
Poor recovery of components
% recovered
Cellulose 90
Hemicellulose 50-60
Lignin (very large error rate)

31. FEED NUTRIENTS
NFE

32. Nitrogen-free extract (NFE)
No actual analysis
Calculation by difference
%NFE = %DM – (%ash+%CP+%EE+%CF)
Theoretically represents:
Starch
Sugars
Problems:
Contains all of the errors from other analyses
Largest error is unrecovered lignin will be placed in NFE

33. WHY IS PROXIMATE ANALYSIS SYSTEM STILL USED?

34. DETERGENT ANALYSIS SYSTEM

35. Uses of the Van Soest system
Predict intake (NDF)
Predict digestibility of forage (ADF)
Determine heat damage (ADF)
Determine Net Energy (NE) and Total Digestible Nutrients (TDN)
Determine degradability of protein in rumen

36. Neutral detergent fiber (NDF)
Consists of hemicellulose, cellulose, lignin, cell wall bound protein and insoluble ash
Significance:
Highly related to feed intake (index of “gut fill”)
Acid detergent fiber (ADF)
Consists of cellulose, lignin, poorly digested protein, and insoluble ash
Highly related to forage digestibility and energy concentration
Combination of DDM (determined from ADF) and DMI (determined from NDF) is used to determine Relative Feed Value (RFV)
Useful for hay marketing

37. Heat Damaged Forages
Typically occurs during ensiling when air gets into the mass.
Result is aerobic rather than anaerobic fermentation
Increase in temperature
Protein and carbohydrate combine = unavailable protein (Maillard reaction)
Determined by ADIN (Acid Detergent Insoluble Nitrogen)
Analysis = ADF; Total N; N in the ADF fraction

38. General Guidelines on Heat Damage
0 – 10% Unavailable protein = little heat damage
11 – 25% Unavailable protein = moderate to severe damage
> 26% Unavailable protein = Severe heat damage
Example: Alfalfa silage
Total N = 3.05% ADIN = 0.25%
3.05 – 0.25 = 2.80% N available
2.80 / 3.05 x 100 = 91.8% nitrogen available or 8.2% unavailable

39. N bound to NDF and ADF is used to determine rumen degradable, rumen undegradable, and indigestible fractions
Rumen degradable protein = Total CP – (NDFCP, % of CP x Total CP)
Rumen undegradable protein = (NDFCP, % of CP xTotal CP) –
(ADFCP, % of CP x Total CP)
Indigestible protein = (ADFCP, % of CP x Total CP)