NUTRITIONAL
REGULATION OF
GROWTH
ANSC 590 ANIMAL GROWTH
AND DEVELOPMENT
NUTRIENT PARTITIONING
Plane of nutrition
 Homeostasis
 Maintenance
 Growth
 Production

 Repro,
milk, finishing, etc.
NUTRIENT PARTITIONING
Dietary energy
 Energy density
 Order of priority for energy on
physiological systems

 Nervous,
circulatory, respiratory, digestive,
and reproductive
 Skeletal, muscle, adipose
NUTRIENT PARTITIONING

Adipose tissues
 Mesenteric
 Perirenal
 Subcutaneous
or intermuscular
 Intramuscular or marbling
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 don’t have
adequate energy for maintenance and production needs

Loss of weight and reduced performance
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
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
feed:gain ratios
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
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
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
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

Dietary Protein
Ruminants utilize microbial protein to
satisfy part of protein requirements
 Amino acids synthesized to ammonia,
CO2, and VFA’s (these are required for
microbial protein growth)- degradation
 Nitrogen is the key for microbial protein
satisfaction (NPN can be a source)

Dietary Protein
Bypass protein – protein that escapes the
rumen
 Degradable versus non-degradable prot.
 Increased muscle accretion requires more
protein

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
Dietary Energy




Requirements increase along with body size
Composition of wt. gain dictates total dietary
energy requirements and f:g 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
Feed Additives
Ionophores- carboxylic polyether
ionophores to increase growth efficiency in
cattle
 Coccidiostats
 Antibiotics

 Subtherapeutic
levels- changes microbes to
improve efficiency
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
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