Helping Low Birthweight Piglets Survive and Thrive

Genetic selection over the last several decades has increased the number of piglets born per litter. While this has improved pigs born alive, it has also increased variation in birthweight, resulting in a higher proportion of low birthweight piglets. These piglets are at a clear disadvantage from birth and contribute disproportionately to pre-weaning mortality, with most losses occurring within the first 72 hours [1,2]. Improving survival of these piglets represents an immediate opportunity to enhance both productivity and animal welfare.

What causes low birthweight piglets?

Low birthweight results from constraints during fetal development.

• Uterine capacity: as litter size increases, the fetuses must compete for space and nutrients within the uterus.
• Placental development: differences in placental size and function limit nutrient supply to some fetuses, resulting in impaired growth [3,4].
• Early differences in development: there can be variation in the timing of ovulation and fertilization, leading to variation in developmental stage of the embryos before implantation.
• Maternal factors: nutrition, body condition, heat stress, and health status all influence fetal growth.

Why do low birthweight piglets have an increased risk of mortality and disease?

Low birthweight piglets are at increased risk of morbidity and mortality because they are born with limited physiological reserves and reduced functional capacity.

• Poor thermoregulation
  Their small body size and higher surface area-to-volume ratio lead to rapid heat loss, increasing the risk of chilling [5].
• Limited energy reserves
  These piglets have fewer energy stores at birth, making them more susceptible to starvation if they do not establish nursing quickly [5].
• Reduced vigor
  Low-birthweight piglets are slower to stand and less able to locate and latch onto a teat, delaying nutrient intake.
• Lower colostrum intake
  Delayed or insufficient colostrum intake reduces passive transfer of immunity, increasing susceptibility to disease [6,7].
• Reduced competitiveness
  Smaller piglets are less able to compete with larger littermates, making it difficult to maintain consistent access to a teat and sustain nutrient intake.
• Increased risk of crushing
  Weaker piglets are less mobile and less able to avoid the sow, increasing their risk of being crushed.

Collectively, these challenges act simultaneously during the immediate postnatal period, creating a cascade of risk that can rapidly lead to mortality without timely and targeted intervention.

How do you identify low birth weight piglets that are at a high risk of mortality?

Low birthweight or growth-restricted piglets can often be identified at birth:

• Small size (commonly <2.5 lb; adjust for your system depending on the genetics of your herd)
• Thin body condition
• Narrow or "dolphin-shaped" head
• Wrinkled skin
• Weakness or delayed movement

Early identification allows you to act when it matters most—within the first few hours of life.

Management priorities: what to do and when

Before farrowing: prevention starts here

Management of low birthweight piglets begins well before farrowing, during pregnancy. Fetal growth and development are highly sensitive to the maternal environment, meaning that decisions made during this period directly influence the number and viability of piglets at birth.

Key areas of focus include:

• Adequate sow nutrition
  Ensure diets meet requirements throughout gestation, with particular attention to late gestation when fetal growth is most rapid.
• Body condition management
  Maintain sows in appropriate condition to support consistent nutrient supply to developing fetuses.
• Heat stress mitigation
  Minimize thermal stress, as elevated temperatures can reduce feed intake and impair fetal development.
• Farrowing management
  Monitor farrowing closely to reduce prolonged labor, which can further compromise the outcomes for the smaller piglets.

Improving the maternal environment during gestation supports fetal development, reduces within-litter variation, and ultimately decreases the number of at-risk piglets at birth.

At birth (0–6 hours): stabilize the piglet

Primary goal: keep the piglet alive and able to nurse

• Warm the piglet immediately
  Dry thoroughly and place in a warm area (~95°F / 35°C).
  → A cold piglet will not nurse.
• Ensure early colostrum intake
  Assist piglets to a teat and hold them in place if needed.
  Use split suckling to improve access.
  → Target intake within the first 6–12 hours [6].

6–24 hours: support intake and access

Primary goal: ensure consistent nursing

• Reduce competition within the litter
  Temporarily remove larger piglets (split suckling).
  Cross-foster after colostrum intake to create more uniform litters
• Monitor and intervene early
  Identify piglets that are:
• Not nursing
• Chilled or isolated
• Weak or inactive

Provide warming, nursing assistance, or supplemental energy as needed.

24–72 hours: maintain survival

Primary goal: prevent losses during the highest-risk period

• Confirm active nursing
  Ensure piglets are regularly accessing a teat
• Continue targeted support
  Provide additional assistance and monitoring for the smaller piglets
• Optimize the environment
  Maintain warm, dry, draft-free conditions
• Adjust litter structure if needed
  Use nurse sows or additional fostering strategies

 Most losses occur within the first 72 hours [1,2], and success depends on early, targeted intervention. Small piglets can survive—but only if their immediate needs are met quickly and consistently.

Key takeaways

• Low birthweight piglets are a major source of pre-weaning mortality
• The first 24–72 hours are critical
• Focus on:
  • Warmth
  • Colostrum intake
  • Reduced competition
  • Close monitoring

Timely, targeted management can significantly improve survival and long-term performance.

References

1. Marchant, J.N., Rudd, A.R., Mendl, M.T., Broom, D.M., Meredith, M.J., Corning, S. and Simmins, P.H. (2000). Timing and causes of piglet mortality. Veterinary Record, 147, 209–214.
2. Le Dividich, J. and Rooke, J.A. (2006). Nutrition and immunology of the neonatal pig. Proceedings of the Nutrition Society, 65, 275–286.
3. Quiniou, N., Dagorn, J. and Gaudré, D. (2002). Variation of piglet birth weight and consequences on subsequent performance. Livestock Production Science, 78, 63–70.
4. Milligan, B.N., Fraser, D. and Kramer, D.L. (2002). Within-litter birth weight variation and its relation to pre-weaning survival. Livestock Production Science, 76, 181–191.
5. Herpin, P., Damon, M. and Le Dividich, J. (2002). Development of thermoregulation and neonatal survival in pigs. Livestock Production Science, 78, 25–45.
6. Devillers, N., Le Dividich, J. and Prunier, A. (2011). Influence of colostrum intake on piglet survival and immunity. Animal, 5, 1605–1612.
7. Quesnel, H., Farmer, C. and Devillers, N. (2012). Colostrum intake: Influence on piglet performance and factors of variation. Livestock Science, 146, 105–114.