SAC Research

To investigate the early life experiences of pigs which grew up to become aggressive, pigs born into 16 litters were investigated. Behaviour and growth were measured at key stages between birth and two weeks after weaning. At the end of this time, aggressiveness was measured in two ways: using a standard individual test and by mixing pigs into new groups.

We have found that certain individual pigs are more aggressive than others in different situations and over a period of time.

These differences in aggressiveness can partly be explained by genetics (see Information Note: Is pig aggression inherited?), but early environment might also play a role.

Problem families...
We have found that certain litters produce more aggressive pigs than others, although we were unable to find anything which explained variation in aggressiveness within a litter. For example no relationships were found with birth order, weight, or teat order.

With a 'harsh' upbringing . . .
Features of aggressive litters included:

• Large litter size at birth
• Low birthweight (see graph)
• Piglets active during the first 8 hours after birth
• Piglets grew poorly over the first 6 days (see graph)

These results suggest that aggressive litters may have had poor nutrition before and in the days after birth, leading to increased activity after birth as piglets struggled to feed at the udder.

Consequences for pig producers
Although more research is needed, piglets from large, slow-growing litters were likely to become aggressive later in life.

Fostering of piglets between litters might reduce this problem, and when purchasing replacement breeding stock, pigs from smaller litters could be selected.

The Scottish Government