Calf Nutrition Issues and Factors Affecting Rumen Development Dr. Howard Tyler Department of Animal Science Iowa State University - PowerPoint PPT Presentation

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Calf Nutrition Issues and Factors Affecting Rumen Development Dr. Howard Tyler Department of Animal Science Iowa State University

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Title: Calf Nutrition Issues and Factors Affecting Rumen Development Dr. Howard Tyler Department of Animal Science Iowa State University


1
Calf Nutrition Issues and Factors Affecting Rumen
Development Dr. Howard TylerDepartment of
Animal ScienceIowa State University
2
Meeting The Nutrient Requirements of the Calf
  • A nutritionists nightmare
  • Entire pre-weaning period is transition period
    from non-ruminant to ruminant
  • proportions of nutrients provided by liquid vs.
    solid feeds in constant flux
  • physical capacity of rumen increases
  • potential for dry matter intake also increases
  • fermentative capacity of rumen increases
  • absorptive capacity of rumen increases
  • therefore, digestibility of solid feeds also
    changes as rumen develops

3
Energy Requirements
  • Approximately 20 kcal/pound of body weight in a
    thermoneutral environment for maintenance
  • Eighty pound calf requires ?1500 kcal maintenance
    and 850 kcal for 0.5 lb of gain (2350 kcal/day
    total)
  • Requirements increase 1 for every degree below
    500 F
  • High surface areabody mass ratio
  • Require 450 kcal more at 200 F (2800 kcal/day
    total)
  • Difference between ruminating calves and
    non-ruminating calves
  • Difference between small and large calves

4
Body Size and Growth Rate Affects Protein
Requirements
  • The size of the calf affects the protein
    requirements at any given level of intake
  • For 95 lb calf receiving 10 ounces of milk
    replacer twice daily, a 2020 milk replacer meets
    the protein needs
  • An 85 lb calf receiving the same amount of milk
    replacer needs 22.5 protein, and a 75 lb calf
    needs 25 protein
  • Less energy needed from maintenance in lighter
    calves, so more energy available for growth
  • Therefore, more protein required to support lean
    growth
  • Required proteinenergy ratio needed changes with
    rate of gain targeted and size of animal being fed

5
Factors Affecting Protein Requirements
  • Rate of gain determines amount of protein
    required
  • If facilities, genetics, and calf
    source/management permit rapid gain, then high
    levels of protein and energy required in diet
  • If facilities, genetics or calf source/management
    LIMIT rate of gain, then protein and energy must
    be reduced accordingly
  • The size of the animal affects the protein
    requirements at any given level of intake
  • Less energy needed from maintenance in lighter
    animals, so more energy available for growth
  • Therefore, more protein required to support lean
    growth
  • Frequency of feeding affects digestive efficiency
  • Natural suckling frequency allows greater intake
    than most hand-feeding systems can achieve
  • Required proteinenergy ratio changes accordingly

6
Imbalanced ProteinEnergy Ratios
  • If energy diverted to immune function (poor
    facilities), then it is NOT available for growth
  • Excess protein must be de-aminated and ammonia
    detoxified and excreted
  • Energy required (3 ATP per molecule of urea) and
    therefore even LESS energy available for growth
    and immunity
  • Overfeeding protein (in this case by underfeeding
    energy) impairs growth and may impair immunity

7
Is Mortality Rate an Issue? (Summary)
  • Under excellent management conditions, there is
    no evidence that calves fed higher levels of
    protein (appropriate for maximal growth rates)
    are at more risk or less risk for dying
  • Under marginal conditions, calves fed higher
    levels of protein may be at higher risk
  • Under highly challenging conditions, calves fed
    higher protein levels are at higher risk of dying
    than calves fed conventionally
  • This begs the question do calves on
  • a higher plan of nutrition have a stronger
  • immune system or a weaker immune system?

8
Does Higher Plane of Nutrition Higher
Functioning Immune System?
9
Does Higher Plane of Nutrition Higher
Functioning Immune System?
10
Does Higher Plane of Nutrition Higher
Functioning Immune System?
11
Does Higher Plane of Nutrition Higher
Functioning Immune System?
12
Challenges with Liquid Feeding Strategies
  • High energy intake from liquid feed delays
    initiation of starter intake and suppresses
    appetite for starter
  • high fat inclusions during cold weather
  • higher solids in the same volume
  • of milk replacer
  • higher volume intakes
  • Must balance accelerated growth with accelerated
    rumen development

13
Establish Microbial Populations
  • After birth aerobic bacteria colonize
  • Anaerobic bacteria soon dominate
  • cellulolytic and methanogenic first
  • lactate-fermenting exceed adult values then
    decline
  • protozoa introduction requires contact with
    mature ruminants
  • Influenced by access to solid feed and the
    composition of the ration

14
Water
  • Water availability may limit starter intake
  • free water necessary for development of rumen
    fermentative capacity
  • water in milk replacer bypasses rumen

15
The Rumen at Birth
  • At birth, the rumen and reticulum are under
    developed, sterile, and non-functional
  • Milk bypasses the reticulorumen by the esophageal
    groove
  • The reticulorumen comprises less than 1/3 of the
    entire stomach volume

16
The Rumen at Weaning
  • The rumen is the primary compartment (over ½ of
    stomach volume)
  • Size, metabolic activity, and blood flow have
    increased markedly
  • The rumen modifies both energy and protein prior
    to digestion by the calf

17
Absorptive Ability of Rumen Tissue
  • The rumen wall consists of two distinct layers
  • musculature
  • absorptive epithelium (mucosa)
  • The mucosa is responsible for absorbing VFA
  • Muscle is develops in response to material in the
    rumen
  • Development of the mucosa depends on the
    production of VFA
  • Roughage does NOT stimulate mucosal growth

18
Rumens of 4-Week-Old Calves
Milk and Hay
Milk, Grain, and Hay
19
What is the Right Balance?
  • Concentrates
  • VFA production
  • butyrate
  • High in energy
  • fermentable carbohydrates
  • Palatable
  • Forages
  • Low in energy
  • structural carbohydrates
  • Ruminal abrasion value (RAV)
  • Bulk
  • Rumination

20
Starter Without Hay
Textured
Commercial textured starter
CP - 23.58 ADF - 6.39
Ground
CP - 25.44 ADF - 6.44
21
Importance of Particle Size
  • Particle size of the diet influences
  • Palatability
  • Speed of digestion
  • Rate of acid production
  • Rumen retention time for digesta
  • Rumen pH via saliva production
  • Integrity of rumen papillae (RAV)

22
Starter With Grass Hay
Coarse 7.5 Hay
Hay of consistent particle size
CP - 23.08 ADF - 6.47
Coarse 15 Hay
Hay of consistent particle size
CP - 22.60 ADF - 7.43
23
Calf Starter with 7.5 Grass Hay
  • Increased body weight
  • Increased feed efficiency
  • Alters rumen VFA production
  • increased acetatepropionate
  • Creates a more stable rumen environment
  • Decreased starter costs
  • significantly improved feeding profitability
  • 4 lbs chopped hay per 50 lb bag of starter

24
Changes in Nutrients Utilized by Calves After
Rumen Development
  • VFA are produced in the rumen and become an
    important source of energy
  • Blood glucose declines
  • Ruminal bacteria increase in population and
    become a primary source of protein
  • 50 protein
  • 80 digestible
  • High biological value

25
Weaning Strategies
  • Level of calf starter intake correlates with
    maturity of rumen fermentative function as well
    as physical development of rumen
  • Weaning should be intake-based
  • Weaning reduces labor costs by 50 and costs of
    gain by 3 to 5-fold
  • earlier weaning of healthy calves is most
    profitable

26
Can A Ruminant Survive Without A Rumen???
  • Rumenectomies (early removal of the rumen) or
    prolonged milk feeding used to answer this
    question
  • Young ruminants will survive for a time without
    rumen fermentation
  • Animal viability decreases and sudden death
    occurs between 6 and 8 months of age
  • Can be reversed almost immediately by providing
    food to the rumen!!!
  • Ruminant animals hard-wired metabolically to
    function as ruminants
  • Must utilize the end-products of microbial
    fermentation

27
On raising calves
  • The first four weeks of its life the calf must
    receive the whole of its mothers milk, because
    in this period the nutrition contained in the
    milk in so small volume can be replaced by no
    other equally nutritious and as easily digestible
    means of food.
  • After four weeks the milk may be replaced by that
    means of fodder which nutritious substance next
    to it in equal weight of dry volume, in the
    greatest possible amount.

USDA, 1847
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