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Feeding Strategies for Dairy Cattle

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Dairy Technology. Nutrition Guidelines for High Producing Herds. Dry Matter intake. 4 - 5% of bodyweight. Neutral Detergent Fibre (NDF) 26 - 30% of DM. Forage NDF. – PowerPoint PPT presentation

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Title: Feeding Strategies for Dairy Cattle


1
Feeding Strategies for Dairy Cattle
2
Rumen Function
  • Rumen functions as flow-through fermentation
    chamber
  • Microbes (starch and fiber digesters)
  • Feed mixing (rumen contractions mix feed, water,
    microbes and saliva)
  • 1-3 rumen cycles per minute)
  • Eructation (remove gases)
  • 30-50 liters per hour
  • Eructated at 200 cm/second (bloat)

3
Rumen Microbes
  • Microbes as a feed source
  • about 50 protein
  • Over 80 digestibility
  • Closer to amino acid profile of milk than any
    other protein source
  • For cow producing 100 lbs milk, 80 of protein
    needs CAN be met by microbial protein (5
    lbs/day)
  • Depends on quality of feeding program (large
    range)
  • DIRECTLY DETERMINES PROFITABILITY OF FEEDING
    PROGRAM

4
Microbial Requirements for Maximal Growth
  • Fluid-based media (water source)
  • Proper temperature (104-106 in rumen)
  • Constant source of substrate (determined by
    feeding program)
  • Proper pH (6.0 target for rumen)
  • Above 6.2 for fiber digesters
  • Below 5.8 for starch digesters

5
Rumen Environment
  • Depends on feeding program
  • Water availability and quality (and temp)
  • Maintains fluid-based media
  • Feed availability and quality
  • Maintains substrate availability
  • Rumen temperature increases with increased forage
  • pH varies dependent on two factors
  • Rate of acid production and rate of removal from
    rumen
  • Rate of buffer production

6
Rumen pH
  • Acid production
  • Primarily VFAs
  • Acetate primarily from fiber digesters (fat
    synthesis in cow)
  • Propionate from all microbes (glucose synthesis
    in cow lactose in mammary gland)
  • Butyrate from starch digesters (rumen epithelium
    energy source and some fat synthesis)
  • Also lactate from specific starch digesters
  • strong acid (high dissociation constant) with
    slow absorption rate from rumen

7
Rumen pH
  • Dilution and flushing effects
  • Water intake flushes acids through digestive
    system
  • Absorption rate
  • The surface area of the rumen (papillae length
    and integrity) and blood flow to the rumen wall
    determine the rate at which acids leave the rumen
  • Buffer production
  • Buffer provided primarily from saliva (sodium is
    primary buffer in saliva)
  • High-producing cows can produce up to 50 gallons
    a day of saliva
  • Cannot replace with feed sources (palatability
    issues)

8
Saliva Production
  • Directly determined by feed intake and
    cud-chewing activity
  • More remastication, more saliva
  • Level of remastication determined by amount of
    feed ingested and particle size of feed ingested
  • Balance between slow rate of digestion (excessive
    particle size) and rumen acidosis (inadequate
    particle size)

9
Feeding Order
  • Feeding forage before feeding concentrates (in
    component-fed herds where forages and
    concentrates are fed separately) will buffer
    rumen before large amounts of acids are produced
  • More stable rumen environment
  • Better forage digestibility, faster rate of
    passage, and increased cow performance compared
    to feeding forages after concentrates

10
Rumen Acidosis
  • Inadequate particle size
  • Decreased remastication
  • Decreased saliva production
  • Decreased pH in rumen
  • Forage digesters Starch Digesters
  • Decreased Digestibility and Rate of Passage

11
Rate of Passage
  • Directly affects level of feed intake
  • Decreased gut motility decreases rate of passage
  • The reverse is not necessarily true
  • Increased forage intake increases rumen
    contractions but decreases rate of passage
  • Decreased digestibility of feeds decreases rate
    of passage
  • Can be feed quality issue or microbe issue
  • Rumen environment affects feedstuff
    digestibility!!!

12
Microbes and Digestibility
  • Each class functions at optimal pH and
    temperature
  • Forage digesters above 6.2
  • Starch digesters below 5.8
  • Above or below optimal environment, digestion
    slows, microbial growth and reproduction slow
  • Dead microbes dont digest anything
  • Also dont grow or reproduce!

13
Feed Quality and Digestibility
  • NDF cell wall material
  • Inversely related to intake
  • 1 increase drops feed intake, milk production
  • ADF cellulose, lignin, ash
  • Inversely related to energy content and
    digestibility
  • Both ADF and NDF positively related to
    remastication and saliva production
  • Must balance needs of cow with needs of rumen
  • Relative Feed Value (RFV) incorporates ADF and
    NDF values to estimate potential intake value
  • Does not include protein in this value
  • Forage value increases 1/ton per unit of RFV
  • PEAQ estimates RFV prior to harvest

14
Fiber Requirements
  • ADF 19 of ration
  • NDF 28 of ration
  • 27 in TMR
  • 29 if particle size inadequate
  • Particle size
  • Top box (gt 0.75) about 8-10 of ration
  • Bottom box (lt 0.3) less than 50 of ration
  • Middle box (0.3 0.75) the rest of the ration

15
Forage for Dairy Rations
  • Forage is the foundation of any ration
  • Most variable component
  • Greatest possibility of having negative impact on
    performance
  • Greatest single factor limiting success of ration
    balancing

16
Forage Harvest Issues
  • Weather fluctuations influence harvest date
  • Harvest date affects forage quality
  • Digestibility decreases 0.5 each day cutting is
    delayed
  • Intake decreases 0.5 each day cutting is delayed
  • Effects are additive feeding value decreases 1
    each day cutting is delayed

17
Fig 17-8. Purchased hay is delivered to an Iowa
dairy farm (Courtesy of Mark Kirkpatrick)
18
Fig 20-5. This extended pile of silage is covered
with plastic that is held in place with
half-tires until it is ready to be fed out
(Courtesy of Howard Tyler)
19
Fig 20-6. Under adverse conditions, plastic
coverings protecting silage can be damaged or
lost, resulting in spoiled or moldy silage
(Courtesy of Howard Tyler)
20
Forage Digestibility
  • Increase rate of digestion by increasing surface
    area
  • Too small of particles does not allow
    remastication
  • Long-stem forage enhances saliva production and
    stabilizes rumen environment
  • Too large of particles slows down digestion and
    decreases rate of passage
  • Decreases feed intake and milk production
  • Must balance particle size needs of rumen with
    intake effects on cow

21
Regulating Feed Intake
  • Physical capacity of rumen
  • Neural control
  • NDF fraction
  • Intake decreases when passage of feedstuffs slows
  • Acidosis
  • Unstable rumen

22
Non-structural Carbohydrates (NSC)
  • Sugars and starches
  • Produce VFAs
  • Rapidly digested
  • Can change rumen pH quickly!!
  • Meet energy needs of microbes
  • Require about 38-40 in ration for this need
  • Can be a challenge in high-fat diets
  • On paper, energy needs of cow are met, but ration
    is actually energy deficient for optimal rumen
    microbial synthesis

23
Fats
  • Increase energy density in ration
  • Do not supply energy to microbes!!!!!
  • Unpalatable, tend to decrease feed intake
  • Over 3 in ration will suppress feed intake
  • Can supplement with rumen protected fats
  • Suppress microbial function
  • Form soaps in rumen
  • PUFAs greater negative effect than SFAs
  • Decrease fiber digestibility, slow rate of
    passage
  • Oilseeds are slow-release form of fat, less
    negative effects in rumen

24
Protein Fractions
  • Dietary proteins classified based on solubility
    in the rumen
  • A
  • NPN, instantly solubilized/degraded
  • B1 B2 B3
  • Potentially degradable
  • C
  • Insoluble, recovered in ADF, undegradable

25
Rumen Degradable Protein (RDP)
  • About 60 of protein in the ration should be
    rumen degradable (RDP) to meet needs of microbes
  • 30 of the protein should be rumen soluble for
    component-fed herds
  • 45 should be rumen soluble in TMR-fed herds
  • Soybean meal is rumen soluble
  • Corn gluten is an insoluble protein source

26
Rumen Ammonia
  • Formed from the breakdown of rumen degradable
    protein
  • RDP broken down to ammonia and carbon and then
    re-formed into higher quality microbial proteins
  • Should be between 2 and 5 mg/dl
  • High ammonia reflects problem with formation of
    microbial proteins

27
Microbial Crude Protein (MCP)
  • Protein produced by microbial synthesis in the
    rumen
  • Primary source of protein to the ruminant animal
  • Microbes combine ammonia nitrogen and
    carbohydrate carbon skeleton to make microbial
    crude protein
  • Diet affects the amount of nitrogen entering the
    small intestine as microbial crude protein

28
Factors Limiting Microbial Protein Synthesis
  • Amount of energy
  • ATP
  • Available nitrogen
  • NPN
  • Degraded feed intake protein nitrogen (RDP)
  • Available carbohydrates
  • Carbon residues for backbone of new amino acid
  • Microbial crude protein synthesis relies on
    synchronization of carbohydrate (for carbon
    backbones) and nitrogen availability (for amino
    group)

29
Microbial Protein Synthesis
  • Synchronization of carbohydrate and N
    availability
  • NPN supplementation
  • Carbohydrates used for carbon skeleton of amino
    acids

Carbon backbone (from CHO fermentation)
30
Microbial Protein Formation
Dietary Starch Sugar
Dietary Cellulose Hemicellulose
rapid
slow
Dietary NPN
Carbon Skeletons
Sulfur
Other Co-factors
rapid
Microbial Proteins
NH3
ATP
Amino Acids
slower
Dietary Insoluble RDP
very slow
Dietary Soluble RDP
31
Synchronous Feeding Challenges
  • Soluble protein sources (SBM) are rapidly broken
    down to ammonia which is primarily used by fiber
    digesters (cellulolytic bacteria)
  • Insoluble protein sources (corn gluten meal) are
    slowly broken down to peptides which are more
    effectively used by starch digesters (amylolytic
    bacteria)
  • For example, feeding NPN in a ration high in
    structural carbohydrates (high forage diet)
    results in ammonia moving to blood rather than
    forming microbial protein

32
Nitrogen Recycling
  • Excess NH3 is absorbed through the rumen wall to
    the blood
  • Quickly converted to urea in the liver
  • Excess NH3 may elevate blood pH
  • Ammonia toxicity
  • Costs energy
  • Urea (two ammonia molecules linked together)
  • Relatively non-toxic
  • Excreted in urine
  • Returned to rumen via saliva (rumination
    important)
  • Efficiency of nitrogen recycling decreases with
    increasing nitrogen intake

33
Nitrogen Recycling
  • Nitrogen is continually recycled to rumen for
    reutilization
  • Ability to survive on low nitrogen diets
  • Up to 90 of plasma urea CAN be recycled to rumen
    on low protein diet
  • Over 75 of plasma urea will be excreted on high
    protein diet
  • Plasma urea enters rumen
  • Saliva
  • Diffuses through rumen wall from blood

Urease
Urea
Ammonia CO2
34
Feed Protein, NPN and CHO
RUP
Feed Protein
AA
Feed Protein
RDP
NH3/NH4
NH3
SMALL INTESTINE
Feed NPN
Bacterial N
MCP
MCP
AA
NH4 loss
RUMEN
Salivary N
Liver
ATP
Blood Urea
35
Ruminant Digestion and Absorption
  • Post-ruminal digestion and absorption closely
    resembles the processes of monogastric animals
  • However, amino acid profile entering small
    intestine different from dietary profile

36
Recycled urea
Salivary Urea
NH3 UREA
LIVER
NPN
Non-utilized Ammonia
Dietary Nitrogen
NH3
PEPTIDES
AMINO ACIDS
LEVEL TO PROVIDE FOR MAXIMUM MICROBIAL GROWTH
POOL
AMINO ACIDS
65 OF PROTEIN
AMINO ACIDS
RDP
PROTEIN
MICROBIAL PROTEIN
SMALL INTESTINE
35 OF PROTEIN
RUP
Reticulo-rumen
37
Milk Urea Nitrogen (MUN)
  • Rumen ammonia that is absorbed into the
    bloodstream is converted to urea by the liver and
    ends up in milk and urine (some in saliva)
  • Optimal MUN levels between 12 and 14 mg/dl
  • High crude protein or a low NSCCP ratio
    increases MUN
  • High MUN (gt20 mg/dl) reflects rations with excess
    protein or inadequate NSC
  • MUN also increases with excessive body condition
    losses (more muscle protein breakdown) as occurs
    in early lactation
  • Must interpret MUN carefully in early lactation
    cows

38
Microbial Protein Synthesis Summary
  • Requires that ammonia (from breakdown of RDP) is
    present at the same time as carbon skeletons
    (from the breakdown of either complex or simple
    carbohydrates)
  • Nutrient synchrony
  • Most crucial when meal feeding, less of a problem
    when rumen is always full of all feeds (TMR fed
    with 24-hour feed availability)

39
Rumen Undegradable Protein (RUP)
  • Protein that by-passes rumen degradation to
    meet the needs of the cow that are not met by
    microbial protein production
  • Should be about 40 of total nitrogen fed
  • Sources include heat-treated soybeans, fish or
    meat meal, distillers grains
  • Optimal LYSMET ratio is 31
  • Typically requires overfeeding protein to meet
    methionine needs of cow
  • Can meet needs with lower RUP and supplemental
    rumen-stable methionine supplements ()

40
Overview of Protein Feeding Issues in Ruminants
  • Rumen degradable protein (RDP)
  • Low protein quality in feed ? very good quality
    microbial proteins
  • Great protein quality in feed ? very good quality
    microbial proteins
  • Feed the cheapest RDP source that is practical
    regardless of quality
  • Rumen undegradable protein (RUP)
  • Not modified in rumen, so should be higher
    quality protein as fed to animal
  • May cost more initially, but may be worth cost if
    performance boosted enough

41
Ionophores
  • Change metabolism within rumen by altering
    microflora to favor propionic acid production
  • Bovatec and Rumensin
  • Fed to heifers to improve live weight gains and
    efficiency of feed utilization
  • Fed to cows to improve feed efficiency
  • Change rumen retention time?
  • May change RDP, RUP, amount of nutrients
    bypassing rumen
  • Ration composition affects profitability of
    ionophore inclusion

42
Water
  • Most overlooked nutrient on many farms
  • 4-5 lbs water required for every lb milk
  • Intake varies by
  • Weather (temperature, humidity)
  • Size of cow
  • Milk production
  • DM consumed
  • DM content of feed
  • Water temperature (effect on rumen function)
  • Water quality

43
Water
  • Necessary for maintaining body fluids and proper
    ion balance, digesting, absorbing, and
    metabolizing nutrients, etc.
  • Cows drink 100 to 200 lbs water per day
  • Heavy producers drink up to 400 lbs
  • Fresh clean water is crucial
  • Clean troughs routinely
  • Intensity of production dramatically affects
    water requirements

44
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45
Fig 14-18. Lactating cows may require over 50
gallons of fresh water daily to maintain high
levels of milk production (Courtesy of Iowa State
University)
46
Fig 14-19. Water quality is as crucial as water
availability (Courtesy of Howard Tyler)
47
Feeding Systems
  • Dictated or limited by facility design
  • Individual feeding systems
  • Component-fed herds

48
Individual Feeding Systems
  • Advantage
  • Ability to feed each cow to her individual needs
  • Disadvantage
  • Labor cost
  • Requirements for specialized housing or
    specialized feeding equipments

49
Component-fed Herds
  • Tie stall barns fed both roughage and
    concentrate feeds
  • Many dairy producers modify this version
  • Concentrates fed at milking time
  • Roughage portion fed at a feed bunk
  • Primary challenge is managing the feed order
  • Provide forage prior to concentrate
  • Frequent feedings are best

50
Fig 15-2. Concentrate is top-dressed on forage
for this component fed herd, allowing cows to
selectively consume ration components (Courtesy
of Iowa State University)
51
Basic Feeding Strategies
  • Feed a TMR instead of component feeding
  • Better feed intake
  • More stable rumen environment
  • Not always possible
  • Frequent feeding enhances feed digestibility
  • 24-hour feed accessibility for lactating cows
  • More stable rumen environment
  • Increase intake potential (exploit feeding
    behaviors)
  • Not always economically feasable

52
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53
Silage Gases
  • Two types of toxic gases can be created
  • Carbon dioxide and nitrogen dioxide
  • Nitrates in plant released as nitric oxide during
    aerobic phase of fermentation (12-60 hours) 1st
    10 days most dangerous
  • Nitric oxide combines with atmospheric oxygen to
    form nitrogen dioxide (heavier than air)
  • Invisible at low concentrations but still toxic
  • Yellowish-brown at high concentrations and very
    deadly smells like bleach
  • Combines with water in lungs to form nitric acid
    permanent lung damage
  • Symptoms resemble pneumonia

54
Dealing With Silage Gases
  • Use proper life-support equipment when entering
    an oxygen-limiting silo
  • Adequate ventilation through roof, open door and
    windows in silo rooms
  • Run blower on upright silos
  • at least 30 minutes

55
Silage Molds
  • Molds that grow when air reaches cured silage
    produce aflatoxins and mycotoxins
  • Organic Dust Toxic Syndrome or Pulmonary
    Mycotoxicosis
  • 4-12 hours after exposure
  • Severe flu-like symptoms for 1-5 days
  • Fever, chills dry cough, severe headache
  • Use mask to prevent molds on silage from entering
    lungs

56
Feeding Moldy Silage
  • Molds and mycotoxins dramatically affect intake
  • Normal spoilage decreases intake by 10-15
  • Higher rates of spoilage reduce intake even
    further
  • Discarding spoiled or moldy silage can increase
    intake, increase milk production and increase
    reproductive performance

57
Nitrate Toxicity
  • Causes
  • ? N fertilization (MUCH worse during drought
    conditions)
  • N in excess of plants reqts for protein
    synthesis
  • sudangrass, sorghum, pearl millet, corn, oats
  • weed-infested forage crops
  • pigweed, smartweed, ragweed, lambs quarter,
    goldenrod, nightshades, bindweed, thistle
  • Rapid accumulation after 1st rain following
    drought or following hard frost
  • Cut corn high for silage highest accumulation
    in lower portions of stalk
  • Toxin does not deteriorate with time!

58
Nitrate Toxicity
  • Nitrates ? Nitrites in the digestive tract
  • Nitrates combine with hemoglobin, form
    methemoglobin
  • Inadequate oxygen transport
  • Symptoms
  • Labored breathing, muscle tremors, staggering
  • Bluish membranes of eyes mouth
  • Chocolate-brown blood turns red when exposed

59
Nitrate Toxicity
  • Control - difficult to treat quick death
  • analyze suspected forages
  • lt 2500 ppm safe
  • 2500 - 5000 ppm caution
  • 5000 - 15000 ppm danger
  • gt 15000 ppm toxic
  • may feed toxic hay in a total mixed ration, if
    thoroughly ground mixed at lt 15 of the diet.
  • Dilute the toxin

60
Cyanide Danger
  • Drought stricken plants
  • Accumulate cyanogenic glycoside, hydrolyzes to
    form free cyanide
  • Danger increases when crops grown on heavily
    nitrogen-fertilized soil
  • Danger increases if frosting, wilting, trampling,
    or hail has occurred

61
Prussic Acid
  • Ingestion of plants containing hydrocyanic
    (prussic) acid
  • Interferes with oxygen transport
  • Blocks mitochondrial uptake of oxygen
  • Symptoms
  • Excessive salivation, rapid breathing, spasms
  • Rapid development of symptoms (10-15 minutes)
  • Dead animals with no symptoms!
  • Bright cherry red blood

62
Prussic Acid
  • Management
  • Graze sorghum only when the plant is gt 15 inches
    tall
  • Do NOT graze
  • During/after drought when plant growth is
    restricted
  • For 2 weeks after a killing frost (wait until
    forage is dry, 24-48 hours)
  • At night when frost is likely

63
What does it all mean???
  • You can take the exact same ration same
    feedstuffs, same amounts fed, same feeding
    program and by changing particle size of the
    forage component (long stem vs. 0.5 vs. finely
    ground), you can dramatically alter performance
    of the animal (milk, growth, etc.)
  • Did not change nutrients fed
  • ONLY change is rumen environment
  • Computer ration balancing program will not show
    you this!!!
  • Its not simply WHAT you feed that determines
    performance
  • What happens in the rumen is MOST important
  • Nutrients provided, physical form of nutrients,
    when they are fed, how often, what order they are
    fed, etc.

64
Nutrition Summary
  • Ration profitability directly depends on how
    cheaply and how efficiently you meet the needs of
    the rumen microbes
  • Post-ruminal feeding includes the most costly
    components of the ration and can be minimized by
    proper rumen management
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