Abstract

Assessing cognitive capabilities of animals is key to understanding their welfare needs.
This is especially the case during major life events or following a change in conditions,
when cognition and welfare needs may change or fluctuate. One such major life event is
gestation, when a female’s physical and physiological environment can change
significantly. In livestock, pregnant females are also frequently subjected to an
environmental change, as they are typically separated from other conspecifics. The aim of
this thesis was to investigate the impact that gestation and early life environment may have
in pigs. This thesis includes two main studies, the first of which focuses on the impact of
pregnancy on cognition and mood, investigating memory, problem solving and personality
throughout pregnancy. This is also the first study, to my knowledge, to use a cognitive
bias approach to assess changes in mood during pregnancy in a non-human animal. In
doing this it was found that there is a significant shift in the pigs’ mood state between
pre/early and mid/late gestational stages, suggesting that they became increasingly
pessimistic as they progressed through pregnancy. The second study investigates how two
key early life factors, the size and sex ratio of the litter an individual is born into, may
influence its later body and tail injury scores as well as cognitive bias when the pigs are
placed in mixed groups in either a barren or enriched environment. A key finding from this
study is that the sex ratio of the litter an individual originates from can have an effect on
its body scores after leaving its litter-mates. It was also found that litter size and relative
weight of the individual within the group can impact upon tail injury scores, though the
nature of the effect also depends on the pigs’ housing environment. Results correlate with
previous findings that litter size is associated with litter sex ratio. Overall this thesis
provides an initial insight into the impacts of pregnancy on a mother’s cognitive bias and
suggests that environmental factors in utero and in early life can influence welfare in later
life.