3. Results
Acute deprivation of straw resulted in gilts vocalising more and lying down for longer periods of time than gilts that were given their usual ration of straw. As expected,
gilts with access to straw continued to root at the straw and remained active for longer than gilts deprived of straw in the hour pre-treatment. This provided an appropriate
w Ž .
Ž . Ž .x
Fig. 2. Median scores for postures, stand a , lie b and change posture c , and the frequencies of scratching Ž .
Ž . Ž .
d , essential behaviours e and vocalising f by pigs housed in a bare or a strawed pen of the same size. The Ž
. error bars indicate the interquartile range lower bar: 25th percentile, upper bar: 75th percentile . Data are
Ž .
Ž .
presented for the hour post-treatment with saline open bars or PGF hatched bars . Bars with different
2 a
Ž .
letters a,b,c,d within each histogram are significantly different P - 0.05, post-hoc Mann Whitney test.
background with which to investigate the effects of PGF and saline on behaviour.
2 a
There was a significant effect of straw and PGF -treatment on all nesting behaviours
2 a
measured in the hour post-treatment. PGF -treated gilts housed with straw had the
2 a
Ž .
Ž highest frequencies of gather U s 1, P s 0.005, Fig. 1a , paw H s 19.2, P s 0.0002,
. Ž
. Fig. 1b and root H s 18.8, P s 0.0003, Fig. 1c . The scores for root and paw were
higher in PGF -treated gilts with access to straw than PGF -treated gilts housed in a
2 a 2 a
Ž .
bare pen U s 5, P s 0.04 . PGF -treated pigs without access to straw rooted for a
2 a
Ž .
Ž longer duration U s 4, P s 0.03 and had a higher frequency of pawing U s 0,
. P s 0.002 than saline-treated pigs housed without straw. Saline-treated pigs housed in a
Ž .
Ž .
straw pen had higher values for root U s 0, P s 0.004 and paw U s 3, P s 0.007 than saline-treated pigs housed in a bare pen. The duration of time gathering straw was
Ž .
higher in PGF -treated than saline-treated pigs U s 1, P s 0.005 . There was a
2 a
significant effect of treatment and housing condition on the amount of time spent Ž
. inactive
H s 13.7, P s 0.0003, Fig. 1d ; saline-treated pigs without access to straw Ž
. were inactive for 10 times longer than pigs in the remaining groups U s 2, P - 0.01 .
Saline-treated gilts housed in a bare pen were observed standing for the shortest Ž
. Ž
duration H s 12.0, P s 0.007, Fig. 2a and lying for the longest duration H s 12.0, .
P s 0.007, Fig. 2b . PGF -treatment resulted in significantly higher frequencies of
2 a
Ž .
Ž .
postural change H s 12.3, P s 0.006 and scratching
H s 17.6, P s 0.0005 , irre- spective of housing condition. There was no significant effect of treatment or straw on
Ž .
essential behaviours H s 2.6, P s 0.4 . There was a significant effect of both substrate Ž
. and treatment on the frequency of vocalisations H s 8.4, P s 0.04 , in which saline-
treated gilts housed in a bare pen vocalised the most and PGF -treated gilts in a strawed
2 a
pen vocalised the least.
4. Discussion
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