PP25 Whole Animal Bone and Fat Development 1

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PP25Whole Animal Bone and Fat Development 1

• Chapter 9 pg 149-178
• ANS 3043
• University of Florida
• Dr. Michael J. Fields

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Changes in Whole Body Form

• Manifested differently depending upon the way the
  body and components are studied
• Components that are more important
  physiologically grow and develop earlier
• Priority of development General Structures
• head gt neck gt thorax gt loin
• Priority of development Tissues
• CNS gt bone gt muscle gt fat

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Small head
Large head
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First
Last
4 Restricted diet takes longer to mature
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Changes in Whole Body Form

• Body changes with age and growth
• Carcass weight
• Body length
• Backfat
• Longissimus area
• Chemical fat
• Kidney fat (develops first)
• Intramuscular fat (develops last)
• Metatarsus (bottom develops first)
• Pelvis (top of pelvis develops last)

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Compare 300 lb to 120 lb so each animal on
similar basis
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Changes in Whole Body Form

• Changes on an absolute basis (cumulative weight
  of muscle, bone and fat over time)
• Maximal growth of each tissue occurs at different
  times
• Fat is most variable of tissues and increases
  dramatically during late growth
• Changes on a percent basis (as a percent of total
  carcass weight)
• Provides an idea of compositional maturity of
  animal

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Level to decline
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Changes in Whole Body Form

• Changes in chemical composition
• Absolute basis
• Water, protein, fat and ash all increase with age
• Percent basis (percent of total composition)
• Water, protein and ash decrease with age
• Fat increases with age

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Water
Fat
Protein
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Less
Increase
Less

Less
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Changes in Specific Tissues

• Percentage Basis
• Muscle
• Water 68-85
• Greatest in early life and decreases with age
• Absolute and percentage protein increases with
  age
• Sarcoplasmic
• Myofibillar

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Less
More
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Changes in Specific Tissues

• Adipose
• Water content high in early development and
  decreases with age
• Protein content is greatest in early development
  and decreases later
• Differences in maturity of aidpose tissue depots
• Kidney gt Mesenteric gt Subcutaneous gt
  intermuscular gt intramuscular

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Changes in Specific Tissues

• Bone
• Water content is high early in development and
  decreases with age
• Protein content is greatest early and decreases
  later in life
• Absolute mineral content increases with age, but
  decreases on a percentage basis
• Fat content tends to increase in spongy bone but
  not compact bone

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Changes in Specific Tissues

• Connective Tissue
• Absolute amount increases with age (associated
  with muscle and tendons)
• Collagen and elastin increase significantly with
  muscle development but decrease on a
  percentagebasis (dillution effect)
• With muscle atrophy (senescence) percentage of
  connective tissue increases with age

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Changes in Specific Tissues

• Minerals (absolute amounts)
• Total amount increases with age
• Not universal for all minerals
• With age, sodium increases and potassium
  decreases
• Calcium and phosphorous both increase

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Allometric Growth

• Growth of a tissue or component in relation to
  the whole
• Tissues grow at different rates dependent on when
  bulk of growth occurs in relation to whole body
• Derived from dissection and weighing of
  individual tissues of components and plotting the
  log weight of tissue or component against log
  weight of total carcass or live weight
• Y axb

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Allometric Growth

• Y axb
• Y log weight of carcass or animal
• a constant (literature)
• x log weight of tissue or component
• b growth coefficient of tissue or component
• Dictates slope of line and whether it increases
  (positive) or decreases (negative) with the
  weight of the whole

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Fat (faster growth)
Muscle (similar growth)
Bone (slower growth)
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Allometric Growth

• b gt 1
• Tissue or component is growing at a faster rate
  than the whole and has a high growth impetus and
  is considered a late developing tissue (i.e.
  total fat)
• b lt 1
• Tissue or component is growing at a slower rate
  that the whole and has a low growth impetus and
  is considered an early developing tissue (i.e.
  total bone)
• b 1
• Tissue or component is growing at a similar rate
  as the whole and has an average growth impetus
  (i.e. total muscle)

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Allometric Growth

• Application of allometric curves muscle example
• Muscle grouping in body of cattle
• Major Muscle Groupings
• Proximal Pelvic Limb Distal Pelvic Limb
• Proximal Thoracic Limb Spinal Column
• Neck-Thorax-Thoracic Limb Abdominal

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Allometric Growth

• Late Developing Muscles (high b)
• Abdominal muscles associated with functional
  demand of rumen
• Neck to thoracic limb associated with increased
  weight bearing duties and potential increase from
  secondary sex characteristics
• Proximal pelvic limb reflective of larger
  muscles of hind limb

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Allometric Growth

• Early Developing Muscles (low b)
• Distal aspects of thoracic and hind limbs
• Proximal thoracic limb
• Similar Developing Muscles (average b)
• Muscles surrounding spinal column

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Allometric Growth

• Types of Allometric Growth Curves
• Monophasic
• Muscle or tissue that has growth coefficient that
  is constant over time
• Diphasic
• Growth coefficients generated over shorter
  periods of time
• Yield dramatically different and sometimes
  contrasting growth coefficients
• Example In early postnantal fat development b
  lt 1
• b gt 1 as fat deposition dramatically increases

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Allometric Growth

• Diphasic growth curves provide more insight into
  how tissues or components grow in relation to the
  whole body

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Fat
Subcutaneous
Kidney