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Growth and Development
Dr. Randy Harp
Growth:
• Growth is an increase in mass– Tissues
• Bone• Internal organs• Muscle• Fat
• True Growth??
Growth:
• Growth is an increase in mass– Tissues
• Bone• Internal organs• Muscle• Fat
• True Growth?Everything except Fat
Normal Postnatal Growth Curves of Bone, Muscle, and Fata
GrowthUnits
Time Units
a Adapted from Boggs, et al, 1998
Bone
Fat
Muscle
Birth
Maturity
Normal Growth Curve of Cattlea
GrowthUnits
Time Unitsa Adapted from Berg & Butterfield, 1976
Birth
Maturity
900 lbs
1100 lbs
1400 lbs
Age:
1) Physiological Age
1) Chronological Age
Age:
1) Physiological AgeDevelopment of the animal relative to maturity
1) Chronological AgeActual Age in days
Fat Tissue Depots:
1) Subcutaneous Fat
2) Internal Fat
3) Intermuscular Fat
4) Intramuscular Fat
Fat Tissue Depots: (order)
1) Subcutaneous Fat ~ Backfat (3rd)
2) Internal Fat ~ KPH (1st)
3) Intermuscular Fat ~ Seam fat (2nd)
4) Intramuscular Fat ~ Marbling (4th)
Normal Postnatal Growth Curves of Bone, Muscle, and Fata
GrowthUnits
Time Units
a Adapted from Boggs, et al, 1998
Bone
Fat
Muscle
Birth
MaturityMarbling
Visual Indicators of Finish
Visual Indicators of Finish
Visual Indicators of Finish
BF .70REA 13.5
YG 3.3
BF 1.50REA 10.6
YG 6.0
Visual Indicators of Finish
Types of Growth:
1) HyperplasiaIncrease in cell number
Occurs during Prenatal growth
Research indicates that cell number is set
2) HypertrophyIncrease in cell size after birth
Benefits to altering growth:
1) Increase in the amount of product to sell
2) Change composition of saleable product
Methods to alter growth:
1) NaturalA) Genetics
British vs European/Continental Breeds
British ~ “Maternal”
Earlier rate of maturity
Less muscle more fat
Continental ~ “Growth and Carcass” “Terminal”
Later rate of maturity
More muscle less fat
F1 Progeny Heterosis
Factors Affecting Growth:
1) Natural B) Nutrition:
1. Types of growing/finishing cattle
a. Grass Cattle - growing
b. Finishing- growing/fattening
Methods to alter growth:1)
2) Adminstered ~ Growth Promoting Agents
A) Implants
- Made of naturally occurring hormones
- Estrogen, Progesterone
Ralgro, Synovex, etc.
- Synthetics Trenbolone Acetate (TBA)
What Implants do:
1) Improved Feed Efficiency
2) Increased Average Daily Gain
3) Increased Dry Matter Intake
4) Increase in Body Mass
What Implants do:
1) Improved Feed Efficiency 15%
2) Increased Average Daily Gain 10%
3) Increased Dry Matter Intake 5-10%
4) Increase in Body Mass 15-20%
Efficiencies and increase in wt gain can result in
50 -150 dollars advantage over non-implanted
Methods to alter growth:1)
2) Administered ~ Growth Promoting Agents
A) Implants
B) Beta Agonists
Beta Agonists:
Ractopamine HCl -
Cattle ~ OptaflexFed last 28-42 days 100 – 300 mg / dayImprovement: 1) Performance
F/G, ADG same DMI 2) Dressing Percent 3) Carcass wt 4) No adverse affect on
Marbling 5) Tenderness affected at 300 mg
Zilpaterol HCl –6.8 g/ton to provide 60-90 mg/hd/dayFed as Showmaxx via layman ORFed in feedlots in concentrate form supervised by a DVM