3.2. Grower period Few behaviour categories showed significant differences during the grower period, as
shown in Table 3. The percentage of observations spent drinking over the total growingrfinishing period was different between treatments. Pigs from the flatdecks
spent a greater percentage of observations rooting in total than those from straw pens, but there was no difference between treatments with regard to straw-directed behaviour
Ž
. P s 0.441 . Pigs from deep-straw pens initially showed a tendency to spend more time
sitting inactive, but this did not persist.
4. Discussion
4.1. Weaner period 4.1.1. BehaÕioural differences between flatdecks
Space allowance, at the levels examined here, did not appear to have a significant Ž
. influence on behaviour. Bure 1984 found increased ‘‘abnormal’’ behaviour in small
Ž
2 2
. flatdecks 0.18 m rpig vs. 0.30 m rpig . However, in the current study, enrichment
appeared to have a much larger influence than space. 4.1.2. BehaÕioural differences between straw pens
There was less straw-directed behaviour in the Straw-Flow pen than in the deep-straw pen, and there were also differences in activity, rooting and playing. These results show
that only a small amount of straw was required to occupy a significant proportion of time, but the quantity supplied here was not sufficient to provide exactly the same
Ž .
benefits as deep-straw. Arey 1993 also reported a tendency for straw-directed be- haviour to increase with the quantity of straw provided. Pen-directed behaviour and
pig-directed behaviour were similar between the two systems, the extra straw-directed behaviour in the deep-straw being accounted for by lower inactivity.
4.1.3. BehaÕioural differences between straw-pens and flatdecks Only 50 g of straw per pig per day, as was available in Straw-Flow, resulted in large
behavioural differences compared to the flatdecks, with regard to straw-directed, pen-di- Ž
. rected, pig-directed social and nonsocial behaviours, nosing, rooting, chewing, and
Ž .
sitting inactive. Van Putten and Dammers 1976 found time spent rooting to be greater among pigs remaining in a bedded farrowing pen than among those transferred to
Ž .
flatdecks at weaning 46.7 and 21.2 respectively . Supplying ‘‘straw in baskets’’ to Ž
pigs in slatted pens has also been shown to decrease tail biting Bure and Koomans, .
1981 . Straw is therefore utilised by pigs as a source of enrichment in a barren environment, serving as a behavioural substrate for a range of different activities.
However, it is not practical for use in fully slatted pens because of detrimental effects on liquid manure management. When compost, which did not block the slurry channels,
was supplied on a board to pigs in flatdecks, ‘‘abnormal’’ behaviour was decreased Ž
. Bure et al., 1983 . The characteristics of the behavioural substrate available are
Ž .
important: when pigs in flatdecks were offered ‘‘toys’’ tyre and chains , they occupied only 0.11 of recorded observations, while pigs in a bedded pen spent 5.48 of
Ž .
observations interacting with straw Britton et al., 1993 . Generally, Straw-Flow shared the behavioural advantages of the deep-straw pen, with
Ž .
fewer potentially damaging to self and others behaviours than the flatdecks examined here. However, the differences in play and other behaviours suggest that deep straw does
provide welfare benefits over and above those of Straw-Flow. This supports the health Ž
. and productivity benefits associated with deep straw reported by Kelly et al. 1998 and
Ž .
Kelly et al. 2000 . Other authors have reported similar behavioural advantages for Ž
straw-based weaner systems relative to flatdecks for example, Bure, 1984; Sebestik et .
al., 1984; McKinnon et al., 1989; Schouten, 1991 . 4.2. Grower period
The pigs in Straw-Flow experienced the least change in environment following transfer to the grower pens. There was a greater area per pig, but the same amount of
available straw per square metre as in the weaner pens. Straw-Flow was therefore the reference group for this period. Pigs from the deep-straw system experienced less straw
than previously and were therefore having to adjust to the ‘‘loss’’, while pigs from the flatdecks gained a solid floor and straw, thus discovering a novel manipulable substrate.
Ž There were behavioural indications greater time sitting inactive, less straw-directed
. behaviour in the first week following transfer to the grower pens that the pigs from the
deep straw pen were relatively ‘‘deprived’’ of straw. However, these tendencies did not Ž
. persist. Boe
1993 found that straw-directed behaviour was increased during the
growing period among pigs weaned into flatdecks compared with those from bedded pens. This was not the case in this study, although total time spent rooting did show
significant differences related to previous housing treatments. The frequency of straw-di- Ž
. rected behaviour during the grower phase was similar to that reported by Pearce 1993 ,
who found that growing pigs on Straw-Flow spent 24.63 of observations in straw-di- Ž
. Ž
. rected behaviour. Sachsenmaier
1984 reported more dog-sitting
sitting inactive , suckling and restlessness when pigs were transferred from enriched to barren pens. In
this trial, pigs from the flatdecks seemed to be taking advantage of the available straw, while pigs from deep-straw took time to adjust to ‘‘less-enriched’’ housing. The most
dramatic effects of early experience reported in the literature relate to loss of enrichment Ž
. i.e. moving from bedded to barren housing , and did not involve commercial systems.
Instead, large and complex housing was compared with fully slatted fattening pens Ž
. Beattie et al., 1993 . It is therefore suggested that since the Straw-Flow grower pens in
the present study were not an extreme environment, residual weaner-treatment effects were not observed. A cross-over study involving pigs from each weaner house being
transferred to either barren or enriched housing might reveal stronger differences.
5. Conclusions
