PP32 Nutrient Partitioning for Growth

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PP32Nutrient Partitioning for Growth

• ANS 3043
• University of Florida
• Dr. Michael J. Fields

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Nutrient Requirements
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Nutrient Requirements

• Maintenance Requirements
• Maintain bodily functions with little or no
  physical activity
• Growth Requirements
• Body tissues muscle, bone, fat
• Depends on location of animal on its growth curve
• Fetal growth if needed

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Nutrient Requirements

• Production Requirements
• Work, lactation, wool, eggs
• Reproduction primarily mating behaviors in
  males
• Effects of environmental stressors
• Modify maintenance and growth requirements
• Climatic conditions, altitude, social behaviors,
  nutrient availability

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Nutrient Partitioning

• Utilization of nutrients is partitioned among
  various tissues and organs according to their
  metabolic rate and physiological importance
• Order of Priority (highest to lowest)

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Nutrient Partitioning

• Altering of Order of Priority
• Pregnancy fetus holds priority similar to vital
  organs of dam
• Species differences, some wild animals will abort
  fetus in order to survive
• Transition from non-lactating to lactating
• Change in priority of nutrients from tissue gain
  to supporting lactating

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Energy Balance

• Positive nutrients are plentiful for body
  maintenance, growth and fattening
• Negative nutrient intake is not sufficient to
  meet these needs
• Lactating dairy cow
• Cant eat enough to meet nutrient demands
• Mobilizes body energy reserves (fat as an energy
  source)

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Growth Rate Efficiency of Growth

• Species differe in their ability to convert feed
  to gain
• Simple stomach animals (grain base diet) have
  greater capacity to ingest metabolizable energy
  per unit of metabolic weight than ruminants
  (forage diet)
• Estimated feed conversions feed/gain
• Chickens 1.0-1.5 / 1
• Pigs 2.0-3.0 /1
• Cattle 5.0-7.0 / 1

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Nutrient Intake

• Prenatal
• Important role of placental in distribution of
  nutrients to fetus
• Fetus has equal priority to maternal organ system
• Under-nutrition results in decreased birth
  weights
• Common in litter bearing animals
• Decreases size of fetus and its organs (less DNA
  content in tissues)
• Decreased skeletal muscle is a result of fewer
  muscle fibers (less potential for postnatal
  muscle hypertrophy)

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Nutrient Intake

• Postnatal
• Requirements for lean growth are met sooner than
  for normal animals
• Grow slower and deposit fat earlier in growth
  curve
• Inferior feed to gain ratios

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Nutrient Intake

• Perinatal Period (during and after birth)
• Metabolic rates increase significantly
• Maintains body temperature of newborn
• Energy initially derived from muscle and liver
  glycogen
• Can also be derived from colostrum
• Some energy derived from brown adipose tissue
• Greater effect in wild species than livestock
  species
• Energy can also be derived from white adipose
  tissue in some species

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Nutrient Intake

• Weaning
• Dramatic changes in quantity and quality of diet
  consumed by animals
• Accompanied by transient decrease in growth
• Some mobilization of fat and possibly muscle
• Diets are balanced to meet protein and energy
  requirements for growing animals
• Easy to overfeed animals resulting in excess fat
  deposition
• Can have a negative effect on future
  productivity, particularly milk production
  because of excess fat in mammary gland
• More effective to limit nutrient intake or slow
  steady gain,
• does not influence muscle growth as long as
  energy and protein requirements are met

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Nutrient Requirements Postnatal Period

• Dietary Protein
• Quantity and quality must be considered together
• More important in monogastric than ruminant
• Ruminants utilize rumen microbial protein for
  some amino acids
• Diets with sufficient energy but insufficient
  protein for tissue deposition result in increased
  fat deposition (primarily monogastric)
• Complicated because animals cannot synthesize
  tissue proteins beyond their genetic potential
• Consumption of excess protein results in surplus
  protein being metabolized for energy or excreted

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Daily nutrient intake recommendations for horses
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Daily nutrient intake recommendations for horses
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Metabolizable protein and energy requirements of
dogs of different physiological sates
aMetabolizable protein, g per W0.75 per day bKcal
per W0.75 kg per day
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Nutrient Requirements Muscle Accretion

• Animals with increased muscle protein accretion
  rates require more protein
• Genetically selected animals
• Administered metabolism modifiers
• Example GH

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Nutrient Requirements Dietary Energy

• Energy required for maintenance increases with
  size
• Energy needed for growth varies with rate and
  composition of body weight gain
• Once energy intake is increased beyond point of
  maximum lean gain, fat gain will start to
  increase significantly because of excess energy
• Since fat contains more energy than protein, the
  energy requirement per unit of body gain
  increases with increased fat
• Composition of gain has a significant impact on
  total energy requirement
• Protein turnover also cost energy and results in
  an increase in energy wasting

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Maintenance requirements of pigs at different
weights
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Growth Rates

• High Growth Rates are a Function of
• Genetics increased genetic potential for
  increased lean growth and ability to convert feed
  to gain
• Sex class of animal (male, female, castrate)
• Location on growth curve self accelerating
  versus self inhibiting
• Need to monitor body weight gain based on body
  composition (lean vs. fat deposition)

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Growth Rates

• Example
• Boar vs. Gilt
• Boars have greater capacity for depositing
  protein, therefore boars have a higher dietary
  energy requirement
• Example Growth Stimulants
• Increased dietary protein deposition increases
  dietary energy requirements

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Compensatory Growth

• Growth exhibited by an animal after a period of
  nutritional stress
• Rate of growth is often greater than that
  exhibited by a genetically identical animal
  during normal growth (catch-up growth)
• Result of several homeostatic and homeorhetic
  effects
• Low basal metabolism during nutrient restriction
  due to decreased visceral weight
• Maintained for a time during realimentation and
  allows more dietary protein and energy for growth
  of major tissues rather than basal metabolism
• Increase in feed intake during realimentation
  contributes to increased growth

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Compensatory Growth

• Severity of nutrient restriction and stage of
  growth curve at which restriction takes place can
  influence how much compensatory growth occurs
• Nutrient restriction severe enough to delay
  catch-up period
• Nutrient restriction early in growth can result
  in long-lasting effects, which are greatest on
  early maturing tissues (bone) and less on later
  maturing tissues (fat)
• Can result in permanent stunting of animal with
  smaller mature body sizes
• Enhances onset of fattening

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Nutrient Partitioning of Energy
Prioritization of nutrients at different planes
of nutrition and weight loss levels.