Behavior of sows exposed to auditory enrichment in mixed or collective housing systems

Abstract

This study investigated the effect of auditory environmental enrichment on the behavior of pregnant and lactating sows housed in mixed (cage until 35 days after insemination and then collective pens) or collective housing (cage until 72 hours after insemination and then collective pens) during the gestation period, as well as the behavior of their litters. A sample of 56 sows of a commercial strain between second and sixth parity was submitted to the treatments from artificial insemination to piglet’s weaning (21 days). The sows were assigned in 2 × 2 factorial randomized block designs in the treatments: mixed housing-control (MH-C), collective housing-control (CH-C), mixed housing-music (MH-M), and collective housing-music (CH-M). The sows in the treatments with auditory enrichment were exposed daily throughout gestation and lactation to 6 hours of classical music (Bach symphonies) divided into 2-hour periods. Behavioral assessment was performed on 10 sows of each treatment once a week. At 21 days of age, their piglets were subjected to tests of novel arena, novel object, and voluntary human approach. In both phases, regardless of the housing system evaluated (CH or MH), females submitted to music had a lower incidence of agonistic and stereotyped behaviors and greater social interaction with other sows and their piglets in relation to the control group. Piglets from the CH-M treatment vocalized less and showed better results in the voluntary approach test. Music as an environmental enrichment reduced agonistic interactions between pregnant and lactating sows and the incidence of stereotypies. Piglets from sows housed in a collective system exposed to sound stimuli in the pre- and postnatal periods were more fearless at 21 days of age.