Social hierarchy and feeder access in a group of 20 sows using a computer-controlled feeder

Abstract

Twenty pregnant sows sharing a double-entry back-out Pig Code feeder with a similar group of 20 were observed over six 24-h feed cycles by a combination of direct observation and video recording. The group had access to an area of 47 m 2 . Sows were fed once a day on a pelleted diet and water was continually available. Feeding order was relatively constant from day to day, and was positively correlated with parity. A social hierarchy based on displacements and attacks within pairs of sows was found to be basically linear, with the exception of six reversals of dominance. Social hierarchy was positively correlated with feeding order overall, but this was not the case for the latter half of the feeding order. This was partly due to disruption of feeder use by non-feeding visits made by earlyfeeding dominant sows. Overall the results showed that older sows with more experience of the feeder in two or three previous parities were higher in the feeding order and social hierarchy than younger sows, and may exclude them from the feeder by repeated non-feeding visits.

Temporal stability of personality traits in group-housed gestating sows

“…Feed order ranking of ESF systems has previously been shown to be fairly stable and correlated to social dominance; with more aggressive and older sows eating earlier than other sows (Hunter et al, 1988;Chapinal et al, 2008). The positive correlation between feed rank at 2 to 4 weeks of gestation and aggressive/dominant scores indicates that sows which displaced others more often, and initiated more aggressive behaviors, also ate their daily feed earlier than other sows.…”

“…Typically a small number of sows (6 to 10) are waiting at the feeder entrance and competing for access the feed station. Given that feed order is relatively stable (Hunter et al, 1988;Chapinal et al, 2008) sows are familiar with their waiting partners and likely have an implicit hierarchy in place. Once inside the electronic feeder the sows eat alone and thus this feeding system is characterized as noncompetitive feeding (Bench et al, 2013).…”

Group housing of sows in early pregnancy: A review of success and risk factors

“…The extent of fighting which occurs in groups of sows depends on group size, management methods and design of the housing system (Edwards and Riley 1986;Hunter et al, 1988;Edwards et al, 1993)". Aggression occurs predominantly because of competition for access to a limited resource, or to establish a social relationship between unfamiliar animals.…”

A Review: Aggression Concerns with Group-Housed Sow Well-Being

“…25 Higher parity sows are involved in more and longer aggressive encounters than lower parity sows, 26 and pregnant gilts that are housed in mixed parity group-pens tend to avoid aggressive encounters 14 while housing only gilts together higher-ranked gilts show more aggression and lowerranked gilts receive more aggression. 27 When group-housed sows are fed individually, social rank influences the order that the group of sows consume feed, with highest-ranked animals entering feeding area first when housed in pens with an electronic sow feeding system or the first feeding stall when a stall system is used.…”

“…27 When group-housed sows are fed individually, social rank influences the order that the group of sows consume feed, with highest-ranked animals entering feeding area first when housed in pens with an electronic sow feeding system or the first feeding stall when a stall system is used. 25,28 Moreover, when sows are floor-fed, the higher-ranked sows will "guard" feed by staying in the center of the feed pile, thus lower-ranked sows only have access to feed on the outer-edge of the pile.…”