Effects of the maternal behavioral characteristics of lying down on piglet crushing in Minpig and Yorkshire sows

Abstract

Maternal crushing has been shown to be the main reason for piglet losses, which occur primarily during sow posture changes. Minpig is a local breed in China with good maternal instincts and lower nursing losses. However, little is known about the behavioral reasons for Minpig sows having fewer piglet losses due to crushing. The primary aim of this study was to compare the posture change, behavioral characteristics of lying down and sow responsiveness to crushing screams between Minpig and Yorkshire sows and investigate which component of behavioral characteristics of lying down movements influenced the probability of piglet crushing. This study was performed with a total of 37 sows, including 17 Minpig and 20 Yorkshire sows. The sow’s maternal characteristics before and during lying down were recorded and a total of 962 events during 72 h postpartum were analyzed. Data were analyzed using PROC GLM and PROC GENMOD of SAS software. The results showed that no difference was observed in the frequency of postural change from standing to lying (P = 0.799), but Minpig sows showed a lower frequency of piglet crushing (P = 0.029) and a lower probability of piglets crushing death (P = 0.052) than Yorkshire sows. Minpig sows exhibited more prelying turning around behavior than Yorkshire sows (P < 0.001). The probability of piglet crushing decreased with an increased frequency of prelying turning around in Minpig sows (P = 0.038), but this effect was not seen in Yorkshire sows (P = 0.396). The duration of sow hindquarter dropping was negatively correlated with the probability of piglets crushing in both breeds (Minpig, P = 0.009; Yorkshire, P < 0.001). Compared with Yorkshire sows, Minpig sows exhibited slower hindquarter dropping when the piglets were present in the danger zone (P = 0.038). Minpig sows exhibited a higher response score and a faster reaction to real piglet crushing (P = 0.007; P = 0.032) or the playback of piglet screams (P = 0.009; P = 0.019) than Yorkshire sows. Overall, more turning around, slower hindquarter dropping and a better responsiveness to piglet screaming might represent dominant elements characterizing Minpig sow behaviors, which are more conducive to piglet survival.