A comparison of postural changes and maternal responsiveness during early lactation in Landrace and Minpig sows

Maternal behaviour is one of the instinct behaviours associated with offspring survival. Minpig is a local breed in the Northeast of China known for its strong maternal sense. In this study, sows of Minpig (n = 30, parity 2–8) and Landrace (n = 21, parity 2–8) were farrowed in individual pens with access to a yard. Sow behaviour was videotaped for 72 h in the second and third week after parturition. The results showed that the Minpig sows and Landrace sows were different in piglet-crushing behaviour (rolling, lying down from a sitting position or a standing position), lateral recumbency, ventral recumbency, and sitting and nursing behaviour (frequency of nutritive nursing and proportion of nursing terminated by the sow). The Minpig sows lie down at higher frequencies from a standing position, but crushing resulting from this movement in the Minpig sows was much less common than in the Landrace sows with only 10 crushing incidents compared to 32, respectively. Crushing occurred most often when the sows changed from the ventral recumbency position to lateral recumbency. In the present study, the total number of occurrences of piglet crushing by the Minpig sows was significantly lower (P < 0.05) than that of the Landrace ones (17 vs. 74). The results indicate that the Minpig sows provided more chances for piglets to escape successfully when the piglets were trapped by her body, leading to 76.5% of the Minpig piglets successfully escaping compared to 18.9% of the Landrace piglets. To explore the reason behind the above results, the carefulness of the sows during standing-to-lying and the responsiveness of the sows to piglet distress calls were investigated. Compared with the Landrace breed, the Minpig   sows scored higher in standing-to-lying carefulness (F¯Minpig=2.4994, F¯Landrace=2.1238, P < 0.01) and higher in responsiveness to piglet distress calls (F¯Minpig=1.7343, F¯Landrace=0.294, P < 0.001). In conclusion, the data suggest that the Minpig sows show stronger maternal instincts through their behavioural postures and their carefulness with piglets compared with the Landrace breed, and this difference may play an important role in the further exploitation of local breeds for the swine breeding program in China.