Raising Replacement Heifers

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Raising Replacement Heifers

• David Marcinkowski
• Dairy Cattle Technology
• AVS346

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Age at First Calving
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Increase First Lactation Milk Yield for Changes
in Body Weight

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Effect of Age at First Calving on Milk per Day
Since Birth

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Calculating Growth Rate

• Endpoint
• 1400 lb at 2 year old
• Starting Point
• Birth Weight 85 lbs
• Gain 1315 lb in 730 days
• 1315/730 1.80 lbs/day
• Weight at 6 months? 1 year? Breeding? Etc.
• 85182.5(1.8)413.5 lb
• 85365(1.8)742 lb
• 85((730-280)(1.8)895 lb

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How Fast is Too Fast?
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Monitoring Heifer Growth Rate
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Growth rates of Holstein replacement heifers from
high producing Wisconsin herds.

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Evaluating Heifer Growth

• Weight Curve
• Associated with available energy
• Height Curve
• Associated with available protein
• Deviations from standard growth curves tell you
  what is lacking and when!

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Holstein Growth Chart - Average Farm
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Holstein Growth Chart - Witter Farm
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Costs to Raise Heifers
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Replacement Heifer Budget Summary
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Rate of Daily Gain and Age at Calving
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Heifer Raising Costs at Different Growth Rates
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Ration Guidelines
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Postpubertal Growth

• Burst of duct development
• Each estrous cycle
• Estrogen
• Responsible for duct growth
• Progesterone
• Works with estrogen
• Secretory tissue

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Prepubertal Development

• Isometric growth
• Birth to 3 months
• Fat connective tissue
• Allometric growth
• Duct growth
• Growth hormone stimulated
• High grain diets-negative effect
• Reduced secretory tissue

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Mammary vs. Body Growth
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Decreased pre-pubertal mammary tissue
differentiation due to

• Excessive energy intake
• Depression of circulating ST levels

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Heifer Reproduction

• Calves from heifers make up 30-35 of the
  replacements
• Heifers have the highest genetic potential
• Conception rates 20-30 than in cows
• Growth rates are the key profitability
• Drawbacks
• Time
• Handling facilities
• Use synchronization
• Prostaglandins, CIDRs and MGA

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Target Breeding Ages, Weights and Heights

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Heifer Reproduction

• Achieve adequate growth rates
• Breed at
• 13-15 months of aged
• Proper weight (750-850)
• Proper height (48")
• Synchronize heats
• Use AI
• 80 conception rate