Assessing long-term behavioural effects of feeding motivation in group-housed pregnant sows; what, when and how to observe

Abstract

Main aim of this study was to elucidate behavioural elements that can be used as a tool to measure satiety in group-housed pregnant sows. In addition, the best time (time of day and time on treatment) and observation method were addressed. In two batches, eight groups of five artificially inseminated nulliparous sows were housed in 17.9 m 2 pens with feeding stalls. Sows were fed at 07:30 and 15:00 h and either had access to a restricted amount of a low-fibre diet (R) or an unrestricted amount of a high-fibre diet (40% sugarbeet pulp) during 30 min (S). Behaviour was scored by focal sampling in five 3-week time periods since the start of the treatments, during 1 h after the morning meal and 1 h before the afternoon meal. All behavioural elements, that are potentially influenced by satiety were scored, including, e.g. social behaviours and tail postures. Data were reduced by excluding or combining behavioural states that had a variation coefficient larger than 100 or a mean appearance of less than 1% of the scoring-time in the R-group (pooled data). Remaining (groups of) behavioural elements that differed between treatments ( P<0.05) were considered to be relevant and were used to reveal relevant periods. Data of the selected periods ( P<0.05 for most selected elements) were used to analyse the morning and afternoon scoring separately. The states Inactive, Self-directed behaviour (combination of, e.g. Sham-chewing and Teeth-grinding), Substrate-directed behaviour (combination of, e.g. rooting and licking substrates), Standing, Moving and Lying lateral and the events Alert and Biting were selected and differed between treatments. In general, S-sows showed less activity than R-sows. Events did not differ between treatments in most separate periods and were, therefore, excluded from further analysis. Differences between treatments in the selected states were only found in the last four periods. Except for Moving (afternoon only) states differed between treatments both in the morning and the afternoon. Differences in the afternoon were, however, more pronounced. It is concluded that at least Inactive, Self-directed behaviour and Substrate-directed behaviour should be used in future ethological studies on satiety in group-housed pregnant sows. These can be scored by scan sampling. The postures Standing and Lying lateral are interesting as well. Observations from 6 weeks after the start of the dietary treatments are most useful and may be done just after feeding, but also several hours after feeding.