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AVS466 Dairy Cattle Nutrition Introduction

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Greater chance of metabolic problems such as acidosis, ketosis, milk fever, laminitis etc. ... put on a per unit of milk basis the incidence of many of these ... – PowerPoint PPT presentation

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Title: AVS466 Dairy Cattle Nutrition Introduction


1
AVS466 - Dairy Cattle Nutrition Introduction
  • David Marcinkowski
  • Extension Dairy Specialist

2
Class Website www.umaine.edu/animlvet/AVS466/ind
ex.htm
  • It can also be reached from my staff page on the
    AVS website

3
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4
Nutrition Affects Everything
  • Production
  • Economics
  • Health
  • Reproduction
  • Growth
  • Labor
  • Genetic Expression
  • Agronomic Systems
  • Impact on nutrient cycles
  • NPK

5
Farm Nutrient Cycle
6
Nutrient Cycles
  • More nutrients (N, P, K) enter the farm in the
    form of feed than fertilizer
  • Can create build up that leads to problems
  • Maine dairy producers buy a lot of grain off farm
  • Nutrients tend to build up in the soil over time.
    It takes 1 - 2.5 acres of land just to get rid of
    the nutrients from one cow. 
  • Pollution potential.
  • N run off into water supplies, ammonia into the
    air
  • P and K build up in soils
  • P runs off with erosion - Eutrophication
  • Much research interest in decreasing excretion of
    these nutrients by gaining better digestion with
    erosion

7
Blame the Nutritionist!
  • Nutrition is so important, blame everything on
    nutrition. 
  • Some problems on the farm are caused by
    nutrition, but many more are caused by
    management, reproduction, genetics, etc.

8
Feeding is Costly
  • Feed represents
  • 40-60 of the total operating costs on dairy
    farms.
  • 70-80 of the cost of raising heifers.
  • Costs include feed that is purchased from other
    sources., but also seed, fertilizer, lime,
    fencing, gas, oil, equipment, repairs, chemicals,
    labor and building (silos etc.)
  • Witter Center feed costs
  • 5.61 per lactating cow per day
  • 1683 per cow per year
  • 7.48 per cwt of milk produced
  • about 67,000 per year for the milking herd

9
High Milk Production With Low Feed Costs
  • Dairy producers always striving for more
    production with less costs
  • Shouldnt they be striving for greater profit?

10
High Production Benefits
  • More milk means more income
  • More milk means more costs
  • More milk means more profit
  • Spreading out maintenance costs over more lbs of
    milk
  • Spreading out fixed/overhead costs over more lbs.
    of milk.
  • Marginal costs go down
  • High production doesnt cause stress

11
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12
Marginal Costs
  • Marginal cost to produce and additional lb of
    milk
  • More production means dilution of the maintenance
    requirement so marginal cost goes down
  • Maintenance costs 1/day
  • Milk production variable costs 10 cents/lb
  • Marginal cost goes down
  • 1 lb/day - 1 1(0.10) 1.10
  • 2 lb/day - 1 2(0.10) 1.20 (0.60)
  • 10 lb/day - 1 10(0.10) 2.00 (0.20)
  • 11 lb/day - 1 11(0.10) 2.10 (0.191)
  • 100 lb/day - 1 100(0.10) 11.00 (0.11)
  • 101 lb/day - 1 101(0.10) 11.10 (0.1099)
  • Milk sells for 15 cents / lb
  • Never want to do anything that reduces milk
    production!

13
High Production Problems
  • Generally increased production is the animals
    response to a reduction in stress
  • Better housing More milk
  • Production increases the risk of problems
  • As production goes up the tightrope gets narrower
  • But if management is there we dont have to see
    more problems
  • Greater chance of metabolic problems such as
    acidosis, ketosis, milk fever, laminitis etc.
  • Greater chance of other health problems-
    mastitis, reproduction, culling etc.
  • When put on a per unit of milk basis the
    incidence of many of these health problems is
    actually less

14
Law of Diminishing Returns
  • As production increases
  • Ration becomes more sophisticated and expensive
  • More difficult to squeeze all nutrients into a
    volume the cow can consume
  • At some point the law of diminishing returns
    kicks in
  • Point exists when an increase in feed cost for an
    additional pound of milk is greater than the
    return form the pond of milk

15
Nutrient
  • Definition
  • A dietary essential for one or more species of
    animal
  • All animals do not require the same nutrients
  • Laboratory analyses determines the nutrients we
    feed
  • Fiber vs ADF
  • Ruminants have simpler dietary nutrient
    requirements because many are supplied by the
    rumen bugs

16
Nutrient Categories
  • Protein
  • Carbohydrates
  • Lipids/Fats
  • Minerals
  • Vitamins
  • Water

17
Chemical Analysis Scheme
18
Protein is Required to
  • Principle component of body tissues
  • Enhance feed intake and energy use
  • Enzymes
  • Supply N to the rumen microbes
  • Ammonia, Amino acids, Peptides
  • Supply amino acids for synthesis of
  • Milk protein
  • Tissue protein
  • Enzymes, hormones etc.
  • What are proteins and amino acids?

19
Chemical Structure of Amino Acid
20
Protein
21
Amino Acids
  • Essential and Nonessential
  • Nonessential - synthesized by body
  • Essential - 10 Essential AAs
  • Necessary for the animal
  • Must come from diet
  • Not a concern in most ruminant diets because
    essential AAs are synthesized by rumen bugs
  • However in higher producing animals we see a
    response to adding certain AAs

22
Protein Terminology
  • Intake protein IP - What the cow eats
  • Crude Protein Calculated from Nitrogen content
    of feed
  • Proteins are 16 N
  • Multiply N content of feed by 6.25 (100/16)
  • Soluble and Insoluble - refer to breakdown in
    water or rumen fluid
  • SIP Quickly available to rumen bugs

23
Protein Terminology
  • Degradable and Undegradable - refers to whether
    it breaks down in the rumen or not
  • Degradable - Broken down in rumen and used by the
    rumen bugs
  • DIP or RDP
  • Undegradable protein is also referred to as
    bypass protein
  • UIP or RUP

24
Protein Terminology
  • Microbial protein - refers to protein produced by
    the bugs in the rumen
  • Calculated from the ration NSC and degradable
    protein available to the bugs
  • If you have a balance of these two you maximize
    rumen microbial activity

25
Two Proteins Available to Cattle
  • True protein - AAs
  • Non-protein nitrogen NPN
  • Any form of available nitrogen
  • Rumen microbes use both sources for the
    production of microbial protein
  • Microbial protein supplies 50 of cows protein
    requirement
  • Microbial protein is much higher quality protein
    than the feed components from which it was
    produced
  • As a result you don't have to worry too much
    about the amino acid (AA) content of the diet or
    providing the essential AA in diet.

26
Essential AA Profiles
27
Proteins in Rumen
  • Proteins hydrolyzed to AAs and peptides
  • Protein degradability
  • Not all bypass protein is equal
  • of dietary protein that is broken down
  • Amino acids have one of two fates
  • Incorporation into microbial protein
  • Deamination to ammonia and VFA
  • Important because some microbes need ammonia
  • Ammonia is used to make other AAs
  • But this process wastes energy because VFA used
    for energy

28
NPN Non Protein Nitrogen
  • Utilized by rumen microbes to make AAs
  • Produces ammonia in the ruminant
  • Several forms
  • Ammonia
  • Urea Most common
  • Rumen has high urease activity Broken down
    Quickly
  • 45 Nitrogen
  • 281 protein
  • Other nitrogenous compounds - Nitrates etc.
  • Use questionable in high producing cows

29
Rumen Ammonia
  • Two Fates
  • Used to form AAs and proteins
  • Process needs carbon skeleton to form AA
  • Carbon comes from sugar or VFA
  • Energy needed
  • Balance of P and CHO important
  • Imbalance causes more ammonia to be absorbed
  • Absorbed by rumen into blood
  • Liver converts to urea
  • Recycled or excreted in urine
  • Conversion requires energy

30
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31
Limitations of Microbial Protein Synthesis
  • Two most likely limitations
  • Energy available
  • NH3 available
  • These need to be synchronized
  • For diets containing urea, may also need
  • Sulfur (for S-containing AA)
  • Branched-chain C-skeletons
  • MO cannot make branched-chain C-chains
  • These normally not a problem

32
Matching Protein and Energy Sources
33
Energy
  • Not a nutrient
  • Obtained from several sources
  • Carbohydrates - CHO
  • Fats - 2.25 times the energy
  • Proteins Via deamination

34
Carbohydrates
  • Major source of energy for cattle
  • Makes up more than 65 of DM in feeds
  • Broken down in rumen to VFAs, methane, carbon
    dioxide and water
  • Two types
  • Structural and Nonstructural
  • Tremendous differences in the speed with which
    structural and nonstructural breakdown in the
    rumen.
  • Structural Slow Nonstructural - Rapid
  • Compatible combination important for good rumen
    digestion

35
Volatile Fatty Acids VFAs
  • Acetic acid 2 Carbons
  • Absorbed by the rumen wall
  • Oxidized throughout the body to generate ATP.
  • Proprionic acid 3 Carbons
  • Removed from portal blood by the liver.
  • In the liver, proprionate used for
    gluconeogenesis
  • Butyric acid 4 Carbons
  • Rumen as ketone beta-hydroxybutyric acid
  • Most used by the rumen wall

36
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37
Carbohydrate Forms
  • Sugars
  • Starches
  • Pectins
  • Hemicellulose
  • Cellulose
  • Lignin
  • 1-3 Nonstructural
  • 4-6 Structural

38
Sugars
  • Glucose, Fructose, Sucrose, Galactose etc.
  • Most easy form to digest
  • Quickly utilized by rumen bacteria within minutes
  • Little to none bypasses the rumen
  • Water soluble
  • Located mainly in the plant cell cytoplasm
  • Present in whole grains and forages

39
Sugars
  • Many byproducts are low in sugars and starches
    because these are removed in the processing of 
    flour, alcohol and sweeteners.
  • Beet Pulp
  • Corn Gluten Feed
  • Brewers grain
  • Distillers Grains
  • Sugars are higher in forages and whole grains
  • Molasses is a good feed to increase sugar content
    of ration

40
Chemical Structure of Glucose
41
Starches
  • Sugar polymers
  • alpha bonds
  • Readily digested in the rumen
  • Breakdown less efficient than SI - Methane
  • Second best energy source for most rumen bugs
  • Hydrolysis to sugars by amylolytic bacteria
  • 50 may bypass rumen Rate of passage
  • Sugars and starches make up NSC
  • Feeds
  • Whole grains highest
  • Forages next
  • Most byproducts are low

42
Chemical Structure of Starch
                                                 
                                                  
     
43
Sugar and Starch Measures
  • Non-structural Carbohydrate
  • Determined Enzymatically with amylase 
  • Non Fiberous Carbohydrate
  • Determined by subtraction
  • NFC DM-NDF-CP-Fat-Ash
  • Includes pectins
  • Expressed as percent of DM
  • NSC and NFC often used interchangeably but they
    are different, because of pectin level.
  • These values will be similar in feeds that have
    little pectin.
  • way off on feeds like beet pulp that have a lot
    of pectin.

44
Pectins
  • Structural carbohydrate?
  • Intercellular glue
  • Linear and branched chains galacturonic acid
    molecules
  • High digestibility in rumen
  • Present in forages and some by products
  • Beet pulp, Citrus Pulp and Soy Hulls

45
Structure of Pectins
Linear and branched chains galacturonic acid
molecules
46
Cellulose and Hemicellulose
  • Cell wall components
  • Structural CHOs
  • Long branched chain polysaccharides
  • Hemicellulose contains pentose sugars (mainly
    xylan) and other compounds
  • Insoluble in water
  • Digestion requires cellulolytic bacteria
  • Slowly digested
  • Digestibility affected by lignin
  • NDF - both
  • ADF - just cellulose

47
Structure of Cellulose
Beta bonding
48
Plant cell wall
49
Lignin
  • Structural carbohydrate - Wood
  • Cell wall component
  • Indigestible by ruminants
  • Fungi
  • Slows digestibility of all other components
  • Present in ADF and NDF
  • Polymer of aromatic alcohols
  • Heavily crosslinked polymer of aromatic/phenolic
    alcohols
  • Forms a net like structure around other cell wall
    components

50
Structure of Lignin
51
Fiber Measures
  • Acid Detergent Fiber
  • Lignin and Cellulose
  • Cell wall of the plant
  • Digestibility is lower
  • Increases as the plant matures
  • Predicts energy level
  • Neutral Detergent Fiber
  • Total cell wall
  • ADF hemicellulose
  • Moderate digestibility
  • Dry matter intake control
  • Increases as plant matures
  • Both expressed as percent of the DM

52
Net Energy Measures
  • Energy level in a feed or ration can be expressed
    in a variety of ways.
  • TDN Total digestible nutrients
  • NFE Nitrogen free extract
  • Net Energy Basis
  • NEM
  • NEL
  • NEG
  • Expressed as Megacalories of Energy - Mcals

53
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54
Net Energy
  • Different types of livestock get different
    amounts of energy from a feed. Depending on
    whether the energy is used for
  • Maintenance
  • Production
  • Growth

55
How are they calculated?
  • The NEM is calculated by determining the amount
    of the feed required to keep an animal at a
    constant weight. 
  • The NEG value of a feed is calculated by
    determining the energy deposited as fat and
    protein in body tissue from feed consumed above
    that needed for maintenance. 
  • The NEL value of a feed is calculated by
    determining the energy utilized to produce milk
    from feed consumed above that needed for
    maintenance. 

56
Net Energy Regressions
  • The NEL content of a feed is difficult to
    determine experimentally, so NEL is not measured,
    but calculated. Usually as a function of
    something that can be measured such as TDN or
    ADF.
  • NEL of Grass 1.085-(0.0150 X ADF) 
  • In this case NEL is a function of ADF!

57
Source of Energy is Important
  • Ground Corn vs Corn Gluten Feed
  • Both have NEL of .89 Mcals/lb
  • GC 9 NDF CGF 45 NDF
  • Which is best?

58
Source of Energy is Important
Which is better?
59
Lipids
60
Fats
  • Also known as Ether Extract
  • Highest energy per lb
  • Chemical structure
  • Fatty acids - Hydrocarbon chains
  • Glycerol
  • Majority absorbed in small intestines
  • Few converted to VFAs
  • Too much fat in the diet inhibits rumen digestion
    of cellulose
  • Fatty Acids inhibit bacteria
  • Coats fiber to prevent breakdown

61
Chemical Structures of Fats
Fatty Acid                                   
Triglyceride
Palmitic Acid 16 Carbons Stearic Acid 18
Carbons Oleic Acid 181 Linoleic Acid 182
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