Use of a nutritional lick block and higher feeding levels to reduce aggression and provide enrichment for sows in groups

There is evidence that providing enrichment may reduce aggression and fighting between sows at mixing (Schaefer et al. 1990), whilst the lack of substrate to allow opportunity for foraging and feel satiated once established in group housing can accentuate ongoing inter-sow aggression (Danielsen and Vestergaard 2001). It was hypothesised that the provision of a higher feeding level or the use of enrichment in the form of a supplemental block would reduce aggression at time of mixing.

A commercial dry sow diet [12.9 MJ digestible energy (DE)/kg, 0.40 g standardised ileal digestible lysine/MJ DE] was fed to all treatments which consisted of a control group fed at 2.3 kg/sow/d, a block enrichment group fed at 2.3 kg/sow/d and provided a 30 kg poured supplemental block (hard block, comprised of a range of ingredients including molasses, sugar beet pulp and magnesium oxide), and a group fed at 4.0 kg/sow/d. All treatments were floor fed once daily at 0700 h. Thirty-six multiparous sows (Landrace X Large White) were used across this study, re-randomised into three treatment groups (n = 6) for each of six replicates. Eighteen sows were used in each replicate, with 18 sows off test, to allow for completely unfamiliar groups at each replicate. This short-term assessment was appropriate given the 1–2 day timeframe associated with dominance aggression at mixing (Arey and Edwards 1998), and accounts for the period that sows can recognise each other (Spoolder et al. 1996). Each experimental replicate ran for 7 days with sows being housed initially in individual stalls for the first 3 days. At 0700 h on d 4 sows were shifted to their allocated group pen (1.5 m²/sow). Daily data collection began on d 4 after mixing. Measures taken during each 4-day observation period included the supplemental block weight, aggressive behaviours (push, chase, attack, bite and threat) and posture observations for 1 hour after feeding. Data were analysed using the Univariate GLM procedure (Genstat, 15th Edition; UK).

The presence of either the supplement block or higher feeding level had a significant positive effect on chase behaviour (Table 1). Sows fed the high feed level or provided with a supplemental block spent more time lying (P = 0.038) and less time standing (P = 0.006), and they also tended to spend less time involved in foraging behaviour than the control treatment (P = 0.084). The provision of a supplement block or a higher feeding level of 4.0 kg/d appears to provide a method to modify the behaviour of the sow at mixing, increasing the time spent at rest (lying) and reducing the exhibition of foraging behaviour.

Table 1.  Mean time (min) sows’ spent engaged in behaviour and posture 1 h after feeding over the 4 d of observation, for sows receiving 2.3 kg/d (Control), sows receiving a high-feeding level (4.0 kg/d, High Feed), or sows receiving a supplement block in addition to 2.3 kg feed/d (Block)