Sow output in Ireland has increased from 21.6 pigs per sow per year in 2003 to 24.5 in 2013. These increases were obtained primarily through an increase in litter size.

However, increasing litter size is negatively correlated with still births, birth weight, birth weight variation, piglet viability, pre-weaning survival and lifetime performance. Piglets weighing less than 800g at birth have a 32 per cent survival rate compared with 97 per cent for piglets weighing more than 2kg.

Several management interventions may help reduce mortality from large litters:

Gestation feeding

Adding fat to the late gestation/lactation diet can increase milk yield and colostrum fat content. This increases survival (+17 per cent) of low birthweight piglets (up to 1kg). However excessive backfat can have the opposite effect.

Stockperson

If the interval between piglets born exceeds 30 minutes the sow should be checked. The farrowing process may be accelerated by injecting the sow wit oxytocin (doses should not exceed 0.5ml). Newborn, low viability piglets should be assisted immediately to suckle the sow to receive colostrum and/or be given an energy-booster.

Inducing farrowing

Sows can be induced by injecting a prostaglandin analogue, instigating sows to farrow around 27 hours later. This should be restricted to overdue sows as inducing farrowing prematurely reduces piglet viability and colostrum quality.

Temperature

Too high a temperature will reduce sow feed intake. Too low a temperature the piglet will not only suffer from hypothermia, but decreased intake of colostrum increasing the likelihood of starvation. Farrowing house temperature should be reduced to 20°C when the youngest piglets are more than two days old.

Colostrum

Piglets need colostrum within six to 12 hours of birth. Immune defence in piglets is immature at birth meaning they depend on the transfer of maternal antibodies from colostrum for immune protection.

The number of piglets should not exceed the number of functional teats. Limit the number of piglets suckling first litter sows to 10. Creep feed may also be placed in the farrowing pen from 14 days.

Cross fostering

Cross fostering should be carried out as soon as possible after birth. Standardise litter size within the first 24 hours ensuring that piglets on each sow are of similar weight.

Crushing

Piglets huddle close to the sow and littermates during the first three days of life. It is advisable to enclose the litter in a creep area before feeding the sow. After feeding and within one hour of locking them in, the litter must be released.

Did you know?

• 60 per cent of foetal growth occurs in the last 30 days of gestation.
• Farrowing house temperature should
• be increased to 24°C before the first piglet is born.
• Farrowing should be complete within five hours; exceeding six hours can double incidence of stillbirths.
• After stillbirths crushing is the second biggest cause of piglet mortality.
• Pre-weaning mortality can be reduced (18 per cent) and stillbirths halved with good supervision. However, excessive disturbance can stress sows, prolonging farrowing and increasing pre-weaning mortality.
• Cross fostering can reduce pre-weaning mortality by 40 per cent.
• Colostrum antibody levels drop 50 per cent within six hours of the first suckling.

The author, Kathryn Reid, is PhD student on the OPTIPIG project investigating methods for optimising annual sow output by increasing the number of viable piglets born alive and minimising pre-weaning piglet mortality through sow nutritional strategies. She is supervised by Dr Peadar Lawlor and Dr Keelin O’Driscoll of Teagasc and Dr Elizabeth Magowan of AFBI and Professor John O’Doherty of UCD.

April 2015