Nursing and weaning behaviour of highly prolific sows in an organic production system

Amid growing concerns for animal welfare and an increasing demand for welfare-focused farming practices, this study investigated the nursing behaviour and weaning process of modern highly prolific sows in a Danish organic production system. The aim was to update our knowledge of the nursing behaviour and weaning process in modern hybrid sows in outdoor production systems. Thus, an observational field study was conducted applying ethological principles of observation. Twelve first-parity sows were observed one day a week during their lactation period between farrowing and abrupt enforced sow-piglet separation. The observed lactation period varied between 54 and 71 days for the individual sows (n = 12) due to varying farrowing times. In total, the sows were observed live for nine weeks at 6.3 hours (mean) daily live observation per sow. For the first seven weeks of observations, cameras were used to obtain 4.6 hours (mean) of daily camera surveillance per sow from inside their huts. During the observation period, the estimated hourly nursing bout rates declined linearly with −0.009 bouts per day (95 % CI: −0.013; −0.004). Yet, none of the observed sows (n/N = 0/12) completed the weaning process naturally before abrupt sow-piglet separation. The estimated mean probability of sows initiating nursing bouts decreased from 5 days (0.48, 95 % CI: [0.36, 0.61]) to 70 days (0.03, 95 % CI: [0.01, 0.06]). The estimated mean probability of sows terminating a nursing bout increased rapidly during the first three weeks of lactation and then remained stable around 0.75 for the rest of the observed lactation period (day 21 = 0.78, 95 % CI: [0.70, 0.85]; day 71 = 0.7, 95 % CI: [0.57; 0.81]). The proportion of nursing bouts performed with the sows standing was overall 0.063 with only four of the observed sows (n = 12) performing this behaviour. Thus, the modern hybrid sows displayed a progression in their weaning process but did not complete it before abrupt sow-piglet separation. Modern, highly prolific sows therefore seem motivated to nurse for longer periods than they most often are allowed in the existing production systems, which might cause welfare implications. • Modern sows in an organic production system displayed a gradual weaning process. • The sows did not complete the weaning process within 10 weeks of lactation. • Resemblance with the gradual weaning behaviour studied in semi-natural environments.