Sheep Gestation Calculator

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A ewe that bred on 13 Dec 2024 has an approximate lambing date of

Friday, May 9, 2025

The due date could fall between 6 May and 12 May. Learn more about the Key Gestation Milestones.

147 Days Until Birth
Photo of calculator author Wes NolteCreated by Wes Nolte.Last updated Jun 10, 2024. References.

How to use the Sheep Gestation Calculator

Using the Sheep Gestation Calculator is straightforward and intuitive. To begin, select the date when the ewe was bred from the calendar input. Once the breeding date is selected, the calculator will automatically compute the expected lambing date. Additionally, it provides a range of possible dates to account for natural variations in gestation length, typically between 144 and 150 days.

Sheep Gestation Milestones

Here's a list of key milestones in sheep pregnancy, broken down by stages:

PhaseTimeCharacteristics
Fertilization and Early PregnancyWeeks 1-2 Starting 13 Dec
  • Mating and Fertilization: Successful mating leads to fertilization.
  • Embryo Formation: Fertilized eggs form embryos and travel to the uterus.
Embryo ImplantationWeek 3 Starting 28 Dec
  • Implantation: Embryos implant in the uterine lining.
  • Early Signs of Pregnancy: Slight behavioral changes might be noticeable.
Fetal DevelopmentWeek 4 Starting 4 Jan
  • Veterinary Confirmation: A vet can confirm pregnancy through palpation or ultrasound.
  • Visible Physical Changes: Enlargement and darkening of nipples; slight abdominal enlargement.
Rapid Growth PeriodWeeks 5-6 Starting 4 Jan
  • Ultrasound Viability: Heartbeats are detectable via ultrasound.
  • Significant Physical Changes: Noticeable increase in the mother's abdominal size; increased appetite.
Preparation for BirthWeek 7 Starting 25 Jan
  • Fetal Development Completion: Lambs develop most features by now.
  • Nesting Behavior: The mother may start looking for a place to give birth.
Pre-Labor StageWeek 8 Starting 1 Feb
  • X-ray Viability: An X-ray can show the number of lambs.
  • Physical Readiness: The mother's body prepares for labor; she may show signs of discomfort.
Final Week and LaborWeek 9 Starting 15 Feb
  • Labor Signs: Restlessness, nesting, loss of appetite, temperature drop.
  • Labor and Delivery: The onset of labor leading to the birth of lambs.
Post-Birth9 May
  • Immediate Postpartum: Ensuring all lambs are nursing and the mother is caring for them.
  • Veterinary Check-up: Post-birth check-up for mother and lambs.
Additional Milestones
  • Health Monitoring: Regular health check-ups throughout pregnancy.
  • Diet and Nutrition Adjustment: Increased and adjusted feeding as the pregnancy progresses.
  • Lambing Preparation: Setting up a comfortable birthing area before the due date.

How Do You Calculate a Sheep's Due Date?

Sheep in a field

Calculating a sheep's due date primarily revolves around the date of mating. Here's a simple step-by-step process to calculate a sheep's due date:

  1. Determine the Date of Mating: Record the date(s) when the ewe was bred. If there were multiple matings, note all the dates.
  2. Understand the Average Gestation Period: The average gestation period for a sheep is about 147 days, but it can range between 144 and 150 days.
  3. Use the First Mating Date as a Starting Point: If you know only one mating date, use this date. If there are multiple mating dates, you can either use the first date or an average of the dates for a rough estimate. Using the first mating date is commonly advised for simplicity.
  4. Add 147 Days to the Mating Date: Count 147 days forward from the mating date to estimate the due date.
  5. Consider the Range: Keep in mind the normal variation in gestation length (144 to 150 days). This means the ewe could deliver a few days before or after the calculated due date.
  6. Monitor for Signs of Approaching Lambing: As the estimated due date approaches, look for signs of labor like nesting behavior, restlessness, or loss of appetite.

Pregnancy Durations For Sheep

The gestation period for sheep is generally consistent. The average gestation period for sheep is about 147 days, but it can range from 144 to 150 days.

Sheep Pregnancy Reference Table

Below is a reference table showing the due date for all days of the year.

Sheep gestation and lambing table for the entire year

References

  1. NSA Next Generation - Start your own flock
  2. MSD Veterinary Manual - Management of Reproduction: Sheep
  3. New Mexico State University - Reproduction in Sheep