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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.
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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 Maturity Muscle Fat Growth Units Birth Bone Time Units a Adapted from Boggs, et al, 1998
Maturity Growth Units Birth Time Units a Adapted from Berg & Butterfield, 1976 Normal Growth Curve of Cattlea 1400 lbs 1100 lbs 900 lbs
Age: • Physiological Age • Chronological Age
Age: • Physiological Age Development of the animal relative to maturity • Chronological Age Actual Age in days
Fat Tissue Depots: • Subcutaneous Fat • Internal Fat • Intermuscular Fat • Intramuscular Fat
Fat Tissue Depots: (order) • Subcutaneous Fat ~ Backfat (3rd) • Internal Fat ~ KPH (1st) • Intermuscular Fat ~ Seam fat (2nd) • Intramuscular Fat ~ Marbling (4th)
Normal Postnatal Growth Curves of Bone, Muscle, and Fata Maturity Marbling Muscle Fat Growth Units Birth Bone Time Units a Adapted from Boggs, et al, 1998
Visual Indicators of Finish BF 1.50 REA 10.6 YG 6.0 BF .70 REA 13.5 YG 3.3
Types of Growth: • Hyperplasia Increase in cell number Occurs during Prenatal growth Research indicates that cell number is set • Hypertrophy Increase in cell size after birth
Benefits to altering growth: • Increase in the amount of product to sell • Change composition of saleable product
Methods to alter growth: • Natural A) 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: • Natural B) Nutrition: 1. Types of growing/finishing cattle a. Grass Cattle - growing b. Finishing- growing/fattening
Methods to alter growth: • Adminstered ~ Growth Promoting Agents A) Implants - Made of naturally occurring hormones - Estrogen, Progesterone Ralgro, Synovex, etc. - Synthetics Trenbolone Acetate (TBA)
What Implants do: • Improved Feed Efficiency • Increased Average Daily Gain • Increased Dry Matter Intake • Increase in Body Mass
What Implants do: • Improved Feed Efficiency 15% • Increased Average Daily Gain 10% • Increased Dry Matter Intake 5-10% • 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: • Administered ~ Growth Promoting Agents A) Implants B) Beta Agonists
Beta Agonists: Ractopamine HCl - Cattle ~ Optaflex Fed last 28-42 days 100 – 300 mg / day Improvement: 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/day Fed as Showmaxx via layman OR Fed in feedlots in concentrate form supervised by a DVM