Review: Improving pig survival with a focus on birthweight: a practical breeding perspective

Area of Science:

• Animal Science
• Genetics
• Animal Welfare

Background:

• Piglet survival significantly impacts farm profitability and animal welfare.
• Preweaning mortality has a disproportionately large effect on profit compared to postweaning mortality.
• Litter size and individual piglet birth weight are negatively associated, affecting survival.

Purpose of the Study:

• To review the relationship between litter size, piglet birth weight, and pig survival.
• To explore genetic strategies for improving piglet survival in breeding programs.
• To identify optimal traits for genetic selection to enhance piglet survival.

Main Methods:

• Literature review of studies on piglet survival, litter size, and birth weight.
• Analysis of genetic strategies and their impact on pig survival traits.
• Evaluation of sow traits (litter size, average birth weight) versus individual piglet traits.

Main Results:

• Litter size primarily impacts mortality indirectly through its effect on average piglet birth weight.
• Average piglet birth weight within a litter is more influenced by environmental factors than individual genetics.
• For preweaning survival, the nurse sow's genetics are more influential; for postweaning survival, the piglet's own genetics are more critical.

Conclusions:

• Breeding programs should prioritize average litter birth weight (a sow trait) over individual piglet birth weight.
• Selection strategies should balance litter size and average birth weight to avoid negative outcomes.
• Combining litter-level average birth weight with individual piglet mortality data offers the most effective approach for improving piglet survival.