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

- Paper III -
2.2 Registration of indicators
2.2.1 Eating behaviour
Although eating speed may differ between sows (Brouns & Edwards, 1994), behavioural
observations of time spend eating is likely to give some indications of feed intake
(Andersen et al., 1999).
For each F-sow, it was recorded whether the sow was eating or not for each half minute
during feeding. A sow was considered eating if she, while chewing had her snout in the
trough or in contact with the floor (Csermely & Wood-Gush, 1990). However, if the sow
shortly lifted her head from the trough or floor still chewing, she was also considered eating.
The recordings began the moment the feed was supplied and stopped 25 minutes (50
recordings) after or until the last sow had stopped eating. Number of times the sow was not
eating compared to number of recordings (max 50) was calculated for each F-sow (% not
eating).
2.2.2 Back fat depth and back fat gain
Measurements of back fat depth is a method to assess the body condition of sows (Charettte
et al., 1996 fra livestock s. 4) and is possible to perform also under practical conditions
(pers.comm., Maes, 2004).
Back fat depth was measured on the F-sows by means of a digital ultrasound back fat indicator
LEAN MEATER ® (Baltic Korn A/S, Naestved, Denmark). All measurements were
performed in the home pen of the sow i.e. in a farrowing crate (at weaning and at farrowing)
or in a group of sows (three weeks after mating). The back fat was measured about 65
mm from either side of the backbone at the 10 th and 12 th (last) rib (conventionally known as
P2-measurements) and all three layers of fat was measured. Four measurements were performed
in all (two at each rib). The average value of the four measurements was used to
characterise the back fat depth of the sow. Observations with more than five mm deviations
between the lowest and highest measurement were excluded from the material (15 sows).
Back fat gain per day were calculated as the difference between back fat at the beginning of
the period and back fat at the end of the period divided with the number of days between
the two measurement days.
2.2.3 Fear tests
Three examples of fear tests believed to be possible to perform in commercial sow herds
were used in this study. These test are further discussed in Kongsted (2004a).
At weaning, when the F-sows were routinely moved from the service to the pregnancy department,
a human approach test (HA-test) (Rousing et al., 1999; Bonde et al., 2003) was
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