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Calcimator

Calving Season Calculator

Calculate bull turnout dates based on your target calving window. Plan breeding season timing and calving spread.

Inputs

days
days
days

Results

Bull Turnout Month

5

Calving Spread

60 days

Bull Turnout Day22
Breeding End Month7
Last Calving Month5
How to Use This Calculator
  1. Enter Target Calving Start Month, January, and February.
  2. Set March, April, and May.
  3. Adjust June, July as needed.
  4. Review Bull Turnout Month and Calving Spread (days).
  5. Use Bull Turnout Day and Breeding End Month to inform your decision.

How the result changes with Gestation Period

Gestation PeriodBull Turnout MonthCalving Spread
273660 days
281560 days
290560 days
297560 days

What each input means

Target Calving Start Month
Month you want calving to begin.
Gestation Period
Average cattle gestation is 283 days. Varies by breed.
Breeding Season Length
Days bulls are with cows. Shorter = tighter calving window.
Desired Calving Window
Target number of days for all calves to be born.

What each result means

Bull Turnout Month
Month to turn bulls out with cows.
Bull Turnout Day
Approximate day of month for turnout.
Breeding End Month
Month to pull bulls.
Last Calving Month
Expected month of last calves.
Calving Spread
Total days in your calving window.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Target Calving Start Month = 3, Gestation Period = 283, Breeding Season Length = 60, Desired Calving Window = 60 = 4 input(s) provided
  2. Calculate Bull Turnout Month
    Bull Turnout Month = min(12
    5 = 5
  3. Calculate Calving Spread
    Calving Spread
    60 = 60
  4. Calculate Bull Turnout Day
    Bull Turnout Day = min(28
    22 = 22
  5. Calculate Breeding End Month
    Breeding End Month = min(12
    7 = 7

Engine last updated . Checked against 2 independently-derived tests how we verify calculators.

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