Accommodation for the peri-parturient sow
Prior to giving birth, sows are normally confined in crates. One of the current aims in pig production is to develop an alternative farrowing system in which the sows are unconfined and grouped together. The aim of the new system is to improve the welfare of the sow and litter whilst maintaining high levels of productivity. Four studies were conducted to document the nest building and social behaviour of sows so that the system can be designed to suit their needs. The fifth study compared the productivity of unconfined individual and grouped sows with confined sows. Study 1. Six sows were housed in a pen which contained a sand floor and straw dispenser. Nine and a half hours before farrowing the sows displayed rooting, pawing and straw carrying and removed 23 kg straw to build a nest with hollow, straw lining and nest rim. Six sows were presented with similar nests. Nest building behaviour was affected by feeding behaviour. Study 2. Sixteen sows were presented with a hollow (H), a mattress (M), a nest box (B) which represented the 3 nest features and a control (C). Farrowing site preference was (H) 6, (M) 6, (B) 4 and (C) 0. In trial 2, (C) was replaced by a straw area (S), all 16 sows farrowed in (S) when it contained 4.5-18 kg straw. At 2.25 kg preference was (H) 1, (M) 3, (B) 1, (S) 3. Nest building behaviour was not affected by the amount of straw in (S).Study 3. Four previously confined and 3 unconfined sows were housed in a pen which included a straw (S), a central food (F) and a control (C) area. Entry into (S) and (C) was contingent on 10 panel presses. Food was delivered into (F) every 2 hours. The sows pressed the panel for (S) more than (C). Nest builidng behaviour was affected by feeding behaviour. Confined sows tended to show more behaviour associated with the straw. In trial 2, 5 sows were housed in pen which included a straw (S), a central (C) and a food (F) area. Cost of entry into (S) and (F) was gradually increased. Food was delivered into (F) every 45 mins. The fall in work rates for straw and food were similar as the cost was increased. The work rate for straw was increased 24 hours before farrowing. Study 4. Twenty-two sows were paired with an unfamiliar conspecific in pens which contained 2 strawed lying areas. As farrowing approached, the sows spent less time lying together and the aggressive behaviour of 12 dominant prepartal sows increased significantly. The level of aggression was significantly reduced in 11 dominant prepartal sows paired with unfamiliar conspecifics in modified pens and between 9 pairs of pre-partal sows which were familiar with each other. Sows were observed to lie together at farrowing and to farrow in more than one lying area. Study 5. Appetite and piglet mortality was compared for 43 sows in straw pens, 51 sows housed with pen-mates in straw pens and 50 sows in farrowing crates. Appetite was not reduced during the periparturient period or affected by pen type. There was no difference in the number of piglets which died during the first 24 hours after farrowing in the 3 pen types. Sows in farrowing crates tended to have more stillborn piglets.