Learning, memory and regulation of the stress response are mediated by the hippocampus. Biologically
relevant hippocampal-dependent tasks that develop and integrate cognitive processing of this region may
not be available to piglets in some current production systems. Additionally, weaning piglets at less than two
weeks of age may make them particularly vulnerable to disruptions during cognitive development. We
measured the effects of a spatial maze task (MT) on the stress response of piglets at weaning (12 days of age)
and subsequent fear response (at 7 weeks of age). Twenty-seven pigs from four litters were assigned to one
of three treatments: maze task (MT), isolation control (IC), or control with sow (SC), then combined into
same sex groups with each treatment represented. Each group was tested four times per day from 5–11 days
of age. MT piglets navigated the MT in order to return to the home farrowing crate containing the sow and
litter. IC piglets were isolated for the same length of time taken for the MT piglet in their group to navigate
the MT. SC piglets controlled for handling and were returned to sow as MT entered the MT. Saliva was
collected immediately pre- and post-MT on day 11 to measure cortisol concentrations, which were lower
pre-MT (F(1, 8) = 5.65, P = 0.04). Weaning at 12 days of age increased cortisol concentrations 2 h postweaning
(F(4, 75) = 5.67, P < 0.001). When exposed to a modified Morris water maze (MWM), a
significant interaction of sex and treatment was found with MT males and IC females faster at solving
the MWM than male IC pigs (x2(2) = 9.14, P = 0.01). Lower cortisol concentrations were seen pre-water
maze versus post-water maze (F(1, 19) = 27.62, P < 0.001). At 50 days of age, fear response of pigs was
examined using three fear-related tests (open field test (OFT), novel object test (NOT), and human approach test (HAT), each consisting of 1 m acclimation and 4 m testing. In the HAT, MT animals had a tendency to
touch the unfamiliar person more quickly (F(2, 19) = 2.51, P = 0.10), and more times than animals in other
groups (F(2, 49) = 6.31, P = 0.008). MT may result in less fear of novel persons and ameliorate cognitive
deficits in male pigs, suggesting benefits of exposing young pigs to environments requiring spatial learning.

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