Sheep Gestation Calculator

Calculate Lambing Date

Understanding Sheep Gestation

Sheep Pregnancy Duration

The average gestation period for sheep is 147 days (approximately 5 months or 21 weeks), commonly remembered as "five months less five days." While the standard is 147 days, normal pregnancies range from 144 to 152 days depending on breed, nutrition, ewe age, number of lambs, and season. Most ewes lamb within 2-3 days of the expected date when accurately bred or artificially inseminated.

Factors Affecting Gestation Length

Breed: Most breeds follow the 147-day standard, though minor variations exist. Finnsheep and other prolific breeds sometimes lamb slightly earlier (145-146 days). Large breeds like Suffolk may go to 148-150 days. Number of Lambs: Ewes carrying singles often carry 1-2 days longer than those with twins or triplets. Ewe Age: Yearling ewes (first-time mothers) sometimes lamb 1-2 days earlier than mature ewes. Nutrition: Undernourished ewes may lamb early or have weak lambs. Season: Fall-bred ewes typically have more consistent gestation than spring-bred ewes.

Sheep Pregnancy Stages

Signs of Impending Lambing

Days 135-145 (1-2 Weeks Before)

• Udder Development: Udder enlarges significantly, becomes firm and shiny. "Bagging up" indicates lambing within 7-14 days
• Abdominal Shape: Belly drops as lambs position for birth. Ewe appears hollow just ahead of hips
• Pelvic Changes: Ligaments around tail head soften, creating hollow depressions on either side
• Behavioral Changes: Ewe becomes more restless, may separate from flock, seeks quiet corners
• Vulva Swelling: External genitalia enlarge and redden

Days 145-147 (24-48 Hours Before)

• Ligaments Completely Soft: Tail head area very soft, can easily lift tail
• Pawing and Nesting: Ewe paws bedding, circles repeatedly, lies down and stands frequently
• Appetite Loss: Many ewes go off feed 12-24 hours before lambing
• Vocalization: Increased bleating, especially in first-time mothers
• Milk Let-Down: Colostrum can be expressed from teats—indicates imminent lambing
• Isolation: Ewe leaves flock, seeks isolated spot

Active Labor (Imminent Lambing)

• Lying Down Repeatedly: Ewe repeatedly lies down, gets up, turns in circles
• Contractions Visible: Rhythmic abdominal contractions, ewe strains
• Water Bag Appears: Translucent sac visible at vulva (may rupture before visible)
• Active Pushing: Strong contractions, ewe vocalizes with each push
• Lamb Appears: Nose and front hooves visible in normal presentation

Pregnancy Management by Stage

Days 0-45 (Early Pregnancy)

Nutrition: Maintain normal feeding—good quality hay or pasture. Avoid obesity or extreme thinness. Target body condition score 2.5-3.5 (scale 1-5). Management: Minimize stress during implantation period (first 3 weeks critical). Avoid mixing groups, rough handling, dog chasing, or extreme weather exposure. Ram Management: Leave ram with ewes 45-60 days for multiple breeding cycles. Remove ram after breeding period ends.

Days 46-100 (Mid Pregnancy)

Pregnancy Check: Ultrasound at day 45-80 confirms pregnancy and number of lambs with high accuracy. Useful for sorting ewes by litter size for differential feeding. Nutrition: Continue maintenance feeding. Ewes carrying multiples need slightly more than singles but major nutrition increase comes later. Health: Trim hooves, deworm according to farm protocol. Address any health issues before late pregnancy.

Days 101-130 (Late Pregnancy)

Critical Nutrition Period: Fetal growth accelerates—70% of fetal growth occurs in final 6 weeks. Gradually increase grain/concentrate from day 100-110 onward. Ewes carrying twins/triplets need significantly more nutrition than singles. Provide high-quality alfalfa or legume hay. Vaccination: Give CD&T booster at day 110-120 to pass immunity to lambs. Monitoring: Watch for pregnancy toxemia (ketosis)—especially in ewes carrying multiples, thin ewes, or obese ewes. Housing: Provide shelter from extreme weather, especially cold and wet conditions.

Days 131-147 (Pre-Lambing to Lambing)

Lambing Area: Move ewes to clean, dry lambing area with fresh bedding. Separate from main flock if possible. Monitoring: Check ewes at least 3 times daily for lambing signs. Some farms use cameras or lamb alert devices. Supplies Ready: Have clean towels, iodine, feeding tubes, lamb milk replacer, lubricant, and other supplies prepared. Shearing: Many farms shear ewes 6-8 weeks before lambing (crutching around udder/tail area minimizes—improves hygiene, easier for lambs to find teats). Nutrition: Provide free-choice quality hay. Gradually reduce grain 2-3 days before expected lambing to prevent udder congestion.

Lambing Process

Normal Lambing Timeline

Stage 1 labor (cervix dilation): 2-6 hours, ewe shows restlessness, pawing, isolation. Stage 2 (lamb delivery): 30 minutes to 2 hours from water bag to first lamb. Single lambs usually born within 30-60 minutes of active pushing. Twins: second lamb typically follows within 15-45 minutes. Triplets: third lamb within 15-30 minutes of second. Stage 3 (placenta): Expelled within 6-12 hours, usually much sooner.

Normal Lamb Presentation

Anterior (head first): 60-70% of births—nose and front hooves first, most common and easiest. Posterior (hind feet first): 20-30% of births—hind feet first, normal but faster delivery needed. Lambs can be born in either presentation without assistance if positioned correctly.

Newborn Lamb Care

• Clear Airways Immediately: Remove mucus from nose and mouth with towel or bulb syringe if ewe doesn't lick clean
• Ensure Breathing: Vigorous rubbing with towel stimulates breathing. Hold lamb upside down briefly to drain fluid
• Navel Dip: Dip umbilical cord in 7% iodine immediately to prevent infection
• Colostrum Critical: Lambs must receive colostrum within 1 hour of birth (6 hours maximum). Test colostrum quality if available
• Warmth Essential: Hypothermia kills newborn lambs quickly. Dry thoroughly, provide heat lamp if cold, or warm in warming box
• Bonding: Keep ewe and lamb(s) together in individual jug (small pen) for 12-48 hours to establish bond
• Ear Tags: Identify lambs with farm ID system within 24 hours
• Tail Docking: If practiced, done at 24 hours to 1 week old using elastrator bands

When to Assist or Call Veterinarian

Common Lambing Problems

Malpresentations

Head back: Front legs present but no head—carefully push lamb back, bring head forward alongside legs. One leg back: Head and one leg visible—push lamb back, find retained leg, bring forward. Breech: Tail first with legs back—most difficult, requires pushing lamb forward, bringing both hind legs into canal. Transverse: Lamb sideways—requires repositioning to anterior or posterior presentation.

Pregnancy Toxemia (Ketosis)

Metabolic disease affecting ewes in late pregnancy, especially those carrying multiples. Causes: inadequate nutrition, obesity, stress. Signs: depression, separation from flock, staggering, blindness, grinding teeth, eventual coma and death. Prevention: proper nutrition in late pregnancy, avoid sudden feed changes or stress. Treatment: oral propylene glycol, IV glucose, corticosteroids (veterinary), immediate lambing may be necessary. Early intervention critical—mortality high once advanced.

Hypocalcemia (Milk Fever)

Low blood calcium, typically occurs just before or after lambing. More common in ewes with high milk production or poor nutrition. Signs: muscle tremors, stiff gait, inability to stand, coma if untreated. Treatment: IV calcium gluconate (veterinary), oral calcium if caught early. Response usually dramatic if treated promptly.

Common Questions

How long are sheep pregnant?

Sheep are pregnant for approximately 147 days (5 months or 21 weeks), with normal range of 144-152 days from breeding to lambing. This is commonly remembered as "five months less five days." Most ewes lamb within 2-3 days of the expected date. Accurately recording breeding dates—using marking harnesses on rams or noting witnessed breedings—allows precise lambing predictions.

Can you tell if a ewe is pregnant?

Yes, through several methods: Return to heat observation (17 days post-breeding—simple but unreliable), ultrasound (day 35-90, highly accurate, can detect number of lambs), blood test (day 30+, detects pregnancy-specific proteins), abdominal palpation (day 70+, requires experience), and visual observation (obvious abdominal enlargement after day 100, especially with multiples). Commercial farms typically use ultrasound at day 45-80 for early confirmation and to sort ewes by litter size.

How many lambs do sheep usually have?

Average litter size varies by breed and management: Most meat breeds: 1.5-2.0 lambs per ewe (mix of singles, twins, occasional triplets). Prolific breeds (Finnsheep, Romanov): 2.5-4.0 lambs per ewe (mostly twins, triplets, quadruplets common). First-time mothers (yearling ewes): typically have singles, occasionally twins. Mature ewes: higher twinning rates than yearlings. Proper nutrition increases lambing percentage—well-fed ewes on "flushing" ration before breeding have higher ovulation rates.

When should I move ewes to lambing area?

Move ewes to clean, prepared lambing area 1-2 weeks before expected lambing date (around day 133-140). This allows ewes to acclimate to new surroundings, reducing stress at lambing time. Moving too early wastes space and increases bedding needs; moving too late risks ewes lambing in main flock where lambs can be lost, chilled, or mismothered. Many farms use "batch" lambing systems where groups of ewes with similar due dates are moved together.

What is the most critical time in sheep pregnancy?

Two critical periods: Early pregnancy (first 3 weeks): Stress, poor nutrition, or rough handling during implantation can cause embryo loss. Late pregnancy (final 6 weeks): 70% of fetal growth occurs now—inadequate nutrition causes weak lambs, pregnancy toxemia, or stillbirths. Ewes need significantly increased energy and protein during this period, especially those carrying multiples. Proper management during these periods determines lambing success and lamb survival rates.

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Our calculator uses the standard 147-day gestation period to provide precise lambing date predictions, helping sheep farmers plan breeding programs and prepare for successful lambing seasons.