NUTRITIONAL REGULATION OF GROWTH

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NUTRITIONAL REGULATION OF GROWTH

• ANSC 590 ANIMAL GROWTH AND DEVELOPMENT

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NUTRIENT PARTITIONING

• Plane of nutrition
• Homeostasis
• Maintenance
• Growth
• Production
• Repro, milk, finishing, etc.

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NUTRIENT PARTITIONING

• Dietary energy
• Energy density
• Order of priority for energy on physiological
  systems
• Nervous, circulatory, respiratory, digestive, and
  reproductive
• Skeletal, muscle, adipose

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NUTRIENT PARTITIONING

• Adipose tissues
• Mesenteric
• Perirenal
• Subcutaneous or intermuscular
• Intramuscular or marbling

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NUTRIENT PARTITIONING

• Homeorhesis longterm coordination of nutrient
  partitioning
• Positive energy balance
• When food is plentiful to take care of
  maintenance, growth and fattening
• Feed efficiency is in favor of greater muscle
  deposition
• Efficiency is in favor of lactation over dry cow
• Negative energy balance when animals dont have
  adequate energy for maintenance and production
  needs
• Loss of weight and reduced performance

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Undernutrition

• Pre-natal fetal concentration of nutrients are
  greater than that of maternal plasma
• Low birth weights are often due to
  undernourishment during fetal development
• Table 11. 1 and 11.2
• Ex. Runt piglets

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Undernutrition

• Runt pigs- less weight with smaller vital organs,
  less DNA in skeletal muscle with less muscle
  fibers. Thus, they grow slower, produce less
  muscle and deposit fat faster or sooner and
  ultimately less feedgain ratios

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Postnatal

• Increased metabolic activity at the time of birth
  for maintaining body temp
• Glycogen and white adipose fat tissues are called
  upon for energy
• Colostrum is essential for energy and for immune
  response
• Milk production plays an integral role in plane
  of nutrition versus growth

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Postnatal

• Weaning- ultimate stress and nutrient change
• Creep feeding
• Ad libitum versus limited feed
• Limited provides less fat intake and deposition
• Yet, has little effect on muscle accretion
• Table 11.5

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Compensatory Growth

• Compensatory growth after a period of nutrient
  restriction
• If fed a high level of nutrition late in
  production after being deprived of nutrients will
  deposit more fat
• If fed a low level of nutrition late in
  production, then they will produce leaner
  carcasses
• Figure 11.9 and table 11.6 7

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Dietary Protein

• Biological value
• Reference to protein quality
• Even though energy is sufficient, protein is
  essential for proper growth
• Tables 11.8,11.9, 11.10
• Yet, excess protein is metabolized for energy
  and/or excreted

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Dietary Protein

• Ruminants utilize microbial protein to satisfy
  part of protein requirements
• Amino acids synthesized to ammonia, CO2, and
  VFAs (these are required for microbial protein
  growth)- degradation
• Nitrogen is the key for microbial protein
  satisfaction (NPN can be a source)

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Dietary Protein

• Bypass protein protein that escapes the rumen
• Degradable versus non-degradable prot.
• Increased muscle accretion requires more protein

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Dietary Protein

• Non-ruminants
• Essential versus non-essential amino acids
• Limiting amino acids in basal diets
• Amino acid balance/supplementation
• Feed intake decreases with amino acid
  deficiencies
• Catabolism of unused a.a.s require energy which
  reduces efficiency
• Table 11.11

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Dietary Energy

• Requirements increase along with body size
• Composition of wt. gain dictates total dietary
  energy requirements and fg ratios
• Supplemental fats are added to give more nutrient
  density
• Non ruminants will assimilate fats to be similar
  type as to the type in the diet
• Soft and oily fat due to melting point and type
  of fats in the feed

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Feed Additives

• Ionophores- carboxylic polyether ionophores to
  increase growth efficiency in cattle
• Coccidiostats
• Antibiotics
• Subtherapeutic levels- changes microbes to
  improve efficiency

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Regulation of Protein Accretion

• Alters rates of protein synthesis and degradation
• Dependent upon nutritional regime versus plane of
  nutrition required
• Synthesis and degradation occurs at varying rates
• Synthesis is more sensitive than degradation
• Amino acid and insulin supplies are important in
  mediating muscle protein metabolism

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Regulation of Protein Accretion

• Protein accretion rates in liver appear to be
  regulated by nutritional status through changes
  in protein degradation rates rather than through
  changes in synthesis rates