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