PP26 Whole Animal Bone and Fat Development 2

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PP26Whole Animal Bone and Fat Development 2

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

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Factors Affecting Whole Body Growth

• Genetics
• Genotype Environment Phenotype
• Growth differences dictated by genotype
• Charolais vs. Jersey
• Quarter Horse vs. Shetland
• Poodle vs. St. Bernard

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Charolais
Jersey
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Quarter Horse
Shetland
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Poodle
Saint Bernard
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Factors Affecting Whole Body Growth

• Growth Differences dictated by selection and/or
  domestication
• Example results in an increased ability of
  animal to produce muscle
• Lack of environmental stressors
• Increased availability of nutrients
• Best shown when comparing very diverse biological
  types within a species

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Genetics

• Bone or Skeleton
• Total skeletal mass influenced by breed and
  mature size
• Large framed animals are taller and heavier at
  maturity
• Grow more rapidly, but mature later
  physiologically
• Deposit fat at a later age, but only upon
  attainment of mature size will there be an
  increased propensity to fatten with excess
  nutrients
• Increases in skeletal size is a result of
  increased long bone growth

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Genetics

• Muscle
• Same number of muscles between and within breeds
• Increased total muscle mass with increased mature
  size
• Associated with increased skeletal growth
• Do not confuse with muscling appearance
• Remember beef breeds have increased number of
  muscle fibers

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Genetics

• Fat
• Most fat deposition follows muscle and bone
  development
• Depends on where animals is on its growth curve
• Fat differences related to time of onset of
  fattening and maturity
• Small framed animals fatten at younger ages and
  lighter weights
• Larger framed animals fatten at older ages and
  heavier weights
• Breed differences relative to the location in
  body where fat is deposited
• Dairy breeds have greater KPH and intermuscular
  fat than beef breeds, which have greater greater
  subcutaneous fat

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Factors Affecting Whole Body Growth

• Species
• Composition is greatly affected by speciation
• Primarily due to increased selection pressures
• Ability to deposit different tissues at different
  rates
• Relative proportions of each body part have
  changed

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Factors Affecting Whole Body Growth

• Nutrition
• Influence on growth rate and body size is
  dependent on
• Animals location on growth curve
• Growing phase (2) vs. Mature phase (3)
• Level of nutrition relative to animals
  maintenance requirements
• Excessive, Met, Below

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Growth dependent on nutrition
Size
Birth Maturity Time
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Nutrition

• Low nutrition nutrient requirements not being
  met
• Below normal muscle and bone growth
• Virtually no fat deposition
• Shifts growth curve to right
• Excess nutrition nutrients higher than required
  for maintenance
• Faster than normal growth and development of
  muscle and bone
• Excess energy partitioned to fat
• Shifts growth curve to left

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Factors Affecting Whole Body Growth

• Sex
• Growth and composition are dependent on sex
• Intact males are capable of higher body weights
  than castrates and females
• Intact males attain compositional maturity at
  later chronological ages than castrates and
  females
• Intact males are generally heavier at any given
  chronological age

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Growth dependent on sex
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Sex

• Muscle
• Changes appear to be related to form and function
• Intact males have greater proportion of muscle
  located in forequarter, specifically in the neck
  and thorax, which are associated with secondary
  sex characteristics
• Increased androgen receptors in these tissues
• Females have increased proportion of muscle in
  pelvic limb and abdominal wall
• Males have larger muscle fiber diameters and
  females and castrates
• Hormonally driven with dramatic effects
• Male gtgt Castrate gtgt Female
• Androgens have greater capacity and prolonged
  impetus for muscle growth

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Weight of tissue, kg
Muscle growth
Weight of carcass, kg
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Sex

• Skeleton
• Unclear if sex class has a direct effect on bone
  growth
• Not know if estrogen and testosterone receptors
  are located on compact or spongy bone
• Indirect effect through multiple mechanisms
  associated with hormone actions (steroids)
• Steer epiphyseal plates slow to close causing
  them to be taller
• Not the case in geldings (species differences)

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Weight of tissue, kg
Bone growth
Weight of carcass, kg
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Sex

• Fat
• Hormonally regulated through steroids with
  dramatic effects
• Example animals at equal slaughter weights
  ranked from leanest to fattest
• Beef Male, Castrate, Female
• Sheep Male, Castrate, Female
• Swine Male, Female, Castrate

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Fat increases
Weight of tissue, kg
Puberty- slow bone muscle growth
Fat growth
Weight of carcass, kg
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Factors Affecting Whole Body Growth

• Sex
• Intact females mature earliest of sex classes,
  whereas castrates are intermediate
• Pigs (exception) gilts mature later and reach
  heavier weights than castrates
• Gilts are leaner than barrows at same
  chronological age (why is un clear)
• Maybe associated with estrogen secretion
  enhancing muscle development

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Factors Affecting Whole Body Growth

• Frame size
• Function of skeletal growth and rate of
  maturation
• Large frame animals reach heavier weights at a
  given compositional maturity
• Takes longer time to reach a given compositional
  maturity than small frame animals
• Considered later maturing animals
• Small frame animals are considered early
  maturing animals

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Angus Charolais Hereford
Small frame
1200 lb has fat of Angus 1,000
lb Frame 3
Large frame
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Large frame
Small frame
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Less Fat
Late maturing
Early maturing
Greater Fat
Weight Constant Basis
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Frame Size Differences

• At a constant chronological age, early maturing
  animals contain a higher percentage of carcass
  fat than late maturing animals
• At a constant weight, later maturing animals are
  leaner, while earlier maturing animals are more
  mature, fatter and further along on the growth
  curve

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Small Frame
Large Frame
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Factors Affecting Whole Body Growth

• Selection
• Dairy vs. Beef
• Selection for muscle is inversely related to milk
  production
• Selection has not changed muscle distribution
• Reduction in muscle fiber numbers in milk breeds
  (occurs in prenatal stage)
• Less muscle fibers uniformly throughout carcass
  during prenatal development

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Increased Bone
Holstein (Friesian)
Hereford
Increased Fat
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Weight of tissue, kg
Bone growth
Weight of carcass, kg
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Dairy- less muscle fibers
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Weight of tissue, kg
Muscle growth
Weight of carcass, kg
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Weight of tissue, kg
Fat growth
Weight of carcass, kg
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Factors Affecting Whole Body Growth

• Selection
• Wool vs. Meat (sheep)
• Strong inverse relationship between production of
  wool (Marino) vs. meat (Suffolk)
• Fine wool breeds are larger framed, fatten at
  heavier weights than meat breeds
• Meat breeds have superior conformation as
  measured by muscle bone ratios

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Suffolk - meat
Marino - wool
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Factors Affecting Whole Body Growth

• Selection
• Maternal vs. Meat (Pigs)
• Maternal (Landrace and Yorkshire) compared with
  meat type (Pietran and Duroc) breeds
• Same compositional differences as observed in
  cattle
• Has not altered distribution of muscle

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Pietran - meat
Yorkshire - maternal
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Distribution muscle not altered
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Factors Affecting Whole Body Growth

• Fat vs. Lean (Poultry)
• Mainly affects abdominal and subcutaneous fat,
  little difference in intramuscular fat
• In contrast to livestock species, selection has
  increased distribution of muscle
• Increase in breast muscle as proportion of total
  carcass muscle

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Little effect on intramuscular fat
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Factors Affecting Whole Body Growth

• Gender effects drive nutrient partitioning
• Why do females fatten sooner?
• Decreased bone growth due to increased estrogen
• Muscle growth starts to decrease and more
  nutrients available for fat
• In males, androgens have greater capacity and
  prolonged impetus for muscle growth