Reproduction performances and conditions of group-housed non ...

- Paper IV -
ing compared to number of recordings (max 50) was calculated for each sow (% not eating).
Three fear tests were performed as indicators of fear. One Human Approach test (HA-test)
were performed when sows were routinely moved at weaning (Rousing et al., 1999; Bonde
et al., 2003). The sow had to pass a human (research technician) at a passage of 10 metres
long and about one meter wide. The human was placed halfway. If the relation between the
time required to approach the person compared to the total time required to pass the 10 metres
were more than 0.67 then the sow was categorised as fearful. Two Forced Human Approach
tests (FHA-tests) were performed in the home arena of the sows (Andersen et al.,
2003, Pedersen et al., 2003) three weeks after mating. The sows’ reaction was categorised
into reaction 1 to 6 and 1 to 3 respectively with low score indicating fleeing behaviour.
Only sows, which scored 1 or 2 in the first and 1 in the second test, were categorised as
fearful.
Involvements in aggressive interactions, skin lesions and lying behaviour during resting
periods were used as indicators of stress. The total number of aggressive interactions the
individual sow participated in together with the number of lost interactions the first hour
after weaning was recorded. The total number of skin lesions on head, ears, neck and
shoulders were recorded for each sow at mating and three weeks after. Every five minute
during resting period at weaning and three weeks after mating for 25 minutes, it was registered
whether the sow was lying solitary (defined as lying/sitting in a distance of 20 cm or
more from other sows) or socially. If the sow was lying alone more frequently than socially,
the sow was categorised as lying solitary.
2.4 Statistical analysis
When analysing the effect of the indicators on the interval from weaning to first mating,
pregnancy chance, culling risk and litter size, the following model was applied:
E(Yijk)= µ+αI(ijk)+γI(ijk) W +γI(ijk) AM +δI(ijk) W +δI(ijk) AM + Ai + Bi(j)+
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∑
u=1
βu xuijk
Where Yijk is the observation for herd i, batch j and sow k. αI(ijk) is the effect of parity group
I(ijk) (1, 2-3 and >3 parity). I(ijk) is an indicator function given the parity of observation
ijk. The indicator functions are specific to each effect, however, to keep Eq. (1) as simple as
possible this I() notation is used throughout. γI(ijk) W and γI(ijk) AM is the effect of fear category
(j,k =fearful, confident) at weaning and three weeks after mating respectively, δI(ijk) W and
δI(ijk) AM the effect of lying behaviour (l,m=lying solitary, lying socially) at weaning and
(1)