Increasing sows’ comfort: do lying mats contribute positively to sow welfare?

Soft flooring may contribute to positive welfare, including comfortable lying behaviour in sows, especially considering the high prevalences of lameness in sows. Rubber mats may function as a practical and less expensive alternative to straw for providing a comfortable lying surface. We hypothesised that providing rubber mats to group-housed sows would improve their lying comfort, and that this would be reflected in their behaviour and lying posture. In total, three groups of 21±4 sows were monitored during three reproductive cycles. From day 28 until d108 of gestation, the sows were housed in group pens with an electronic feeding system (EFS). The floor of the pen consisted of 15.9 m2 solid, rubber-covered lying area (A), 15.9 m2 solid, concrete lying area (B), 8.0 m2 slatted, rubber-covered walking area (C) and 10.6 m2 solid floor around the EFS (D). The behaviour of the sows was recorded (scan sampling, with an interval of 30 minutes between 5.00-19.00 h and a scan at 23.00 and 3.00 h) during two periods in the reproductive cycle: just after moving them to the group housing (d28-d31, period (1) and around mid-gestation (d50-d54 (period 2). In addition, sows’ gait was observed on d28 and d50. The effect of rubber lying mats on lying behaviour was analysed, regarding gait score. A preliminary data analysis was performed on the proportion of time in one of the areas and on the proportion of lying posture within an area. Preliminary results (based on 78% of the total recorded data) showed that the sows performed less inactive behaviour (e.g. standing immobile, lying and sitting) in period 1 than in period 2 (86.4 vs 93.3%; P=0.02), irrespective of being lame or not (P>0.1). Sows were inactive for 96% of the time they spent in area A or B. Inactivity was less prevalent in area C 38.0% (P<0.01) and area D 56.5% (P<0.01). Lying posture (sternal, semi-lateral and lateral lying) did not differ between lame vs non-lame sows (all P>0.36), nor for observation period (all P>0.08). Time spent lying sternal did not differ between the 4 areas (1.3%; P>0.3). Semi- lateral lying was less common in area C than in A, B and D (7.9 vs 28.8, 27.5, 25.4%; P<0.0001). Lateral lying was more common in areas A or B (64.6%) as compared to area C (13.1%, P<0.01) or D (19.4%, P<0.01). In conclusion, under the conditions of the present experiment, covering solid concrete floors with 20 mm rubber mats did not improve lying comfort as it did not affect lying preference or lying posture of lame and non-lame sows.