A study by AFBI scientists found that piglets born later in the farrowing process are less likely to survive, irrespective of birth weight.
The project looked at more than 2,100 piglets born from more than 140 sows during four separate pig trials.
Scientists tracked the birth order of the piglets and placed them into three categories – early piglets which were born from first to fifth, middle piglets which were born from sixth to tenth, and late piglets which were born from the eleventh onwards.
Research found that piglets born from the eleventh in birth order onwards had a 77% chance of survival, compared to 83% for early piglets and 85% for middle piglets.
The study found that piglets born early in farrowing are more robust, meaning they are less likely to be stillborn, drink more colostrum and gain more weight in the first 24 hours of life.
The study also found that, as expected, piglets which survive lactation and the nursery period are heavier at birth (1.38kg) than piglets who do not survive (1.10kg).
However, the research showed that birth order had no relationship to birth weight and that late piglets tended to have the same weight (1.39kg) as early piglets (1.37kg).
The findings were presented at a research conference at AFBI Hillsborough on pig health, management, and environmentally sustainable production.
Dr Ramon Muns, head of AFBI’s Monogastric Research Group, said: “Most of the management after farrowing is based on trying to save pigs at a lower weight but what we found was that birth order can be equally important to body weight.
“The higher mortality observed among ‘late’ born piglets is not due to weight but more likely due to low oxygen levels during a long birth process and subsequent low vitality.
“Farmers already spend a lot of time in the farrowing room making sure that all piglets have the same chance of success.
“If we could bring the survival of ‘late’ pigs from 77% up to 83-84% survival (same level as in ‘early’ and ‘middle’ pigs), we would increase overall litter survival by 3 to 5% (almost one extra piglet assuming 16 total born piglets).
“One extra piglet per sow (using £50 as a reference/approximate price for a weaner, extra feed for the sow not accounted for) could result in an additional ≈£100 per sow per year.”