Use of recorded nursing grunts during lactation in two breeds of sows. I. Effects on nursing behaviour and litter performance

Abstract

The impact of exposing lactating sows and their litters to recorded sow nursing grunts played at different intervals during lactation was studied. Yorkshire × Landrace (YL) and 25% Meishan (MH) primiparous sows were divided into three groups (n = 14): (1) no playback, (2) playbacks at 35-min intervals (GR35), and (3) playbacks at 40-min intervals (GR40). Recordings were played from day 110 of gestation to day 27 of lactation. Nursing behaviours, incidence of nursings without milk ejection (NPN), nursing interval and proportion of nursings induced by playbacks were measured on days 6, 18 and 26 of lactation. Litter size was standardized to 10 ± 1 piglets within 48 h of birth and piglets were weighed weekly. Mean nursing intervals, excluding NPN, were shorter for MH than for YL sows (P < 0.001). The increase in mean nursing interval between days 6 and 18 was greater in GR40 than in GR35 or controls (P < 0.01) and, when excluding NPN, the mean nursing interval decreased in GR35 on day 18 (P = 0.01). The occurrence of NPN decreased as lactation advanced (P < 0.001) and was lower for MH than YL sows on day 26 (P < 0.001). Between days 6 and 18, the proportion of nursings initiated by playbacks increased (P < 0.05) and the duration of milk ejection decreased (P < 0.001). In MH sows, controls had longer milk ejections than GR35 (P < 0.05) whereas, in YL sows, controls had shorter milk ejections than GR40 (P < 0.05) and GR35 (P = 0.06). Piglet growth was not affected by treatments or breed (P > 0.1). In conclusion, exposing sows and their litters to recorded sow nursing grunts played at 35-min intervals reduced nursing intervals on day 18 of lactation only, without affecting piglet performance. Key words: Auditory stimulus, behaviour, lactation, litter performance, Meishan, sows