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AVS466 Dairy Cattle Nutrition Introduction


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

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

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

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

Farm Nutrient Cycle
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
  • 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

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

Feeding is Costly
  • Feed represents
  • 40-60 of the total operating costs on dairy
  • 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

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

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
  • Spreading out fixed/overhead costs over more lbs.
    of milk.
  • Marginal costs go down
  • High production doesnt cause stress

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Marginal Costs
  • Marginal cost to produce and additional lb of
  • 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

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

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

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

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

Chemical Analysis Scheme
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?

Chemical Structure of Amino Acid
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

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

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

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

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
  • Microbial protein is much higher quality protein
    than the feed components from which it was
  • 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.

Essential AA Profiles
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

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
  • 45 Nitrogen
  • 281 protein
  • Other nitrogenous compounds - Nitrates etc.
  • Use questionable in high producing cows

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

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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

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

  • 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
  • Structural Slow Nonstructural - Rapid
  • Compatible combination important for good rumen

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
  • Butyric acid 4 Carbons
  • Rumen as ketone beta-hydroxybutyric acid
  • Most used by the rumen wall

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

  • 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

  • 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

Chemical Structure of Glucose
  • 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

Chemical Structure of Starch
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.

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

Structure of Pectins
Linear and branched chains galacturonic acid
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

Structure of Cellulose
Beta bonding
Plant cell wall
  • 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
  • Forms a net like structure around other cell wall

Structure of Lignin
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

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

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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

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

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
  • NEL of Grass 1.085-(0.0150 X ADF) 
  • In this case NEL is a function of ADF!

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?

Source of Energy is Important
Which is better?
  • 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

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