Swine Gestation Calculator

Calculate Farrowing Date

Understanding Swine Gestation

Swine Gestation Period

The average gestation period for pigs is 114 days, commonly remembered using the "3-3-3 rule": 3 months, 3 weeks, and 3 days. This consistent timeline makes pig breeding and farrowing highly predictable compared to other livestock. Normal gestation ranges from 112 to 116 days, with most sows farrowing within 1-2 days of the expected date when bred naturally or through artificial insemination.

Factors Affecting Gestation Length

Breed: Commercial breeds (Yorkshire, Landrace, Duroc, Hampshire) all follow the standard 114-day gestation with minimal variation. Litter Size: Larger litters may result in slightly shorter gestation (112-113 days), while small litters may go slightly longer (115-116 days). Parity: Gilts (first-time mothers) sometimes farrow 1 day earlier than experienced sows. Nutrition: Properly nourished sows carry to term; undernourishment can cause premature farrowing. Season: Heat stress in summer may slightly shorten gestation.

Swine Pregnancy Stages

Signs of Approaching Farrowing

Days 110-112 (2-4 Days Before)

• Udder Development: Mammary glands enlarge significantly, become firm and warm to touch
• Vulva Changes: Vulva swells and reddens
• Behavioral Changes: Increased restlessness, may become aggressive or protective
• Appetite Changes: Some sows go off feed 12-24 hours before farrowing

Day 113-114 (12-24 Hours Before)

• Nesting Behavior: Sow gathers and arranges bedding materials, paws and roots
• Milk Let-Down: Colostrum/milk can be expressed from teats—indicates farrowing within 12-24 hours
• Temperature Drop: Rectal temperature may drop 1-2°F below normal (102.5°F)
• Increased Vocalization: Grunting, restless behavior
• Lying on Side: Sow lies on side frequently, exposing udder

Active Farrowing

• Contractions Visible: Rhythmic abdominal contractions every 10-15 minutes initially
• Water Bag: Amniotic sac may appear (often breaks unnoticed)
• First Piglet: Usually born within 2-3 hours of active labor starting
• Subsequent Piglets: Born at 15-20 minute intervals on average
• Duration: Complete farrowing typically takes 2-6 hours

Pregnancy Management by Stage

Days 0-30 (Breeding to Implantation)

Nutrition: Feed maintenance ration (4-5 lbs/day for commercial sows). Overfeeding during this period can reduce embryo survival. Management: House in groups or individual stalls. Minimize stress—no mixing with unfamiliar pigs, avoid temperature extremes, reduce handling. Confirmation: Observe for return to heat at 18-24 days post-breeding. If no heat observed, assume pregnant. Ultrasound possible from day 18-20.

Days 31-90 (Early to Mid-Gestation)

Nutrition: Maintain at 4-6 lbs/day depending on body condition. Target body condition score 3.0-3.5 (scale of 1-5). Pregnancy Check: Ultrasound at day 30-35 confirms pregnancy with high accuracy. Health: Vaccinate and deworm according to herd protocol. Most farms vaccinate at day 60-80 for diseases like E. coli, erysipelas, parvovirus. Exercise: Group housing provides social interaction and exercise—improves farrowing performance.

Days 91-110 (Late Gestation)

Nutrition: Increase feed gradually from day 90 onward, reaching 6-8 lbs/day by farrowing. Higher fiber diets reduce constipation risk. Move to Farrowing Room: Transfer sows to farrowing crates/pens at day 110-112. Allows acclimation before farrowing. Hygiene: Wash sows thoroughly before moving into farrowing rooms to reduce pathogen transfer to piglets. Comfort: Ensure proper temperature (60-65°F for sows), good ventilation, clean dry bedding.

Days 111-114 (Pre-Farrowing)

Monitoring: Check sows at least twice daily for farrowing signs. Some farms use video monitoring for continuous observation. Reduce Feed: Cut feed to 2-3 lbs on day 113 to reduce constipation and facilitate farrowing. Supplies Ready: Have towels, iodine, heat lamps, feeding tubes, oxytocin, and other farrowing supplies prepared. Staff Availability: Ensure experienced staff available to attend farrowings 24/7 during expected farrowing window.

Farrowing Process

Stage 1 Labor (Preparation)

Lasts 2-6 hours. Sow shows restlessness, nesting behavior, occasional straining. Contractions increase in frequency and intensity. Sow typically lies on her side. Most sows farrow lying down, though some may stand between piglet deliveries.

Stage 2 Labor (Piglet Delivery)

First piglet usually born within 2-3 hours of stage 1 labor starting. Average litter size: 10-14 piglets (varies by breed, parity, and genetics). Piglets born at approximately 15-20 minute intervals—faster than cattle, slower than sheep/goats. Total farrowing duration: 2-6 hours typically. Piglets born in amniotic sac (usually breaks during passage). Both anterior (head first) and posterior (tail first) presentations are normal in pigs.

Stage 3 (Placenta Expulsion)

Placentas pass intermixed with piglet deliveries or shortly after last piglet. One placenta per piglet, though may be interconnected. Complete expulsion within 2-4 hours of last piglet is normal. Sows may eat placental tissue—normal behavior but not necessary.

Newborn Piglet Care

• Clear Airways: Remove mucus from nose and mouth immediately. Vigorous rubbing with towel stimulates breathing
• Dry Piglets: Towel dry thoroughly, especially in cold weather. Hypothermia is leading cause of piglet death
• Navel Care: Dip navel in 7% iodine immediately after birth to prevent infection
• Warmth Critical: Provide heat source (heat lamp, heated mat). Newborn piglets need 90-95°F initially
• Colostrum Essential: Piglets must nurse within 1 hour of birth. Colostrum provides immunity—absorption decreases rapidly after 6 hours
• Iron Injection: Give 200 mg iron dextran injection at 1-3 days old to prevent anemia
• Teeth Clipping: Clip needle teeth within 24 hours if practicing (reduces facial lacerations on sows and littermates)
• Tail Docking: If practiced, done at 1-3 days old (controversial—some countries ban)
• Ear Notching/Tagging: Identify piglets with farm ID system within 24 hours

When to Assist or Call Veterinarian

Post-Farrowing Care

Immediate Post-Farrowing (0-24 Hours)

• Ensure All Piglets Nurse: Confirm each piglet has nursed within 2 hours. Assist weak piglets if needed
• Cross-Fostering: Equalize litter sizes—move piglets to sows with smaller litters or similar farrowing dates
• Sow Observation: Monitor sow for retained piglets, excessive bleeding, mastitis, or agalactia (milk failure)
• Placenta Check: Verify placenta fully passed. Count placental remnants (should equal number of piglets)
• Feed and Water: Offer small feed amount and plenty of water. Gradual return to full feed over 3-5 days

First Week Post-Farrowing

• Monitor Sow Health: Check udder daily for mastitis (heat, swelling, discolored milk), monitor body temperature, observe appetite
• Piglet Growth: Weigh piglets at day 3-7 to assess growth. Healthy piglets gain 0.5-0.75 lbs daily
• Creep Feed: Introduce creep feed at 7-10 days to prepare piglets for weaning
• Castration: Male piglets castrated at 7-14 days if practiced

Common Questions

How long are pigs pregnant?

Pigs are pregnant for 114 days on average (range 112-116 days). This is easily remembered with the "3-3-3 rule": 3 months, 3 weeks, and 3 days. Breed, litter size, and nutrition have minimal impact—gestation is remarkably consistent compared to other livestock. Accurately recording breeding date allows precise farrowing prediction, enabling proper preparation and supervision.

When should I move a pregnant sow to the farrowing room?

Move sows to farrowing rooms at day 110-112 of gestation (approximately 3-4 days before expected farrowing). This allows sows to acclimate to new surroundings, reducing stress at farrowing. Moving too early wastes farrowing room space; moving too late doesn't allow acclimation and may result in sow farrowing in gestation housing. Thoroughly wash sows before moving to reduce pathogen transfer to clean farrowing environment.

How many piglets do pigs usually have?

Average litter size is 10-14 piglets, though highly productive modern genetics can produce 14-18 piglets per litter. Litter size varies by: Parity (first litter typically 9-11 piglets; mature sows produce larger litters), genetics (some lines selected for prolificacy), nutrition and body condition, boar fertility, and season (slightly smaller litters in heat stress periods). Stillborn rate typically 5-8% of total born.

Can you check if a pig is pregnant?

Yes, multiple methods: Return to heat observation (21 days post-breeding—simplest, least reliable), ultrasound (day 18-35, highly accurate, requires equipment and training), blood test (day 30+, detects pregnancy-specific hormones), abdominal palpation (day 30-60, requires significant experience), and visual observation (abdominal enlargement obvious after day 80-90). Most commercial farms use ultrasound at day 30-35 for early pregnancy confirmation, allowing culling of open sows.

Why is accurate gestation tracking important?

Accurate tracking enables: Precise farrowing room allocation (avoiding overcrowding or empty space), proper timing of sow movements and preparations, appropriate staff scheduling for 24/7 farrowing attendance, batch farrowing management (grouping farrowings for efficiency), vaccination and health protocol timing, nutritional management adjustments, and maximizing facility utilization. In commercial operations, accurate records are essential for reproductive performance analysis and genetic selection decisions.

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Our calculator uses the standard 114-day gestation period to provide precise farrowing date predictions, helping pig farmers optimize breeding programs and prepare for successful farrowings.