Sow dimensions increase with increasing parity but not with increasing litter size

In most of indoor farrowing accommodations, sows are housed in crates. During mating and gestation many sows are in stalls, or are being fed in feeding stalls or in Electronic Sow Feeders. Increasing consumer awareness of sow welfare makes it important to ensure that sows do not risk injuries associated with crates or stalls that are too small (Pedersen 2015). Therefore, it is important that crates, stalls and feeding stations meet the space requirements of sows. Dimensions of Danish crossbred-sows were measured several years ago (Moustsen et al. 2011). Based on those measurements, recommendations for dimensions of crates, stalls, and pens were decided on. Body dimensions of sows increase with increasing parity but whether or not increased litter size leads to increases in body dimensions, or whether larger sows give birth to larger litters, has not been investigated. The objective of the present study was to determine whether body dimensions of Danish crossbred sows had increased (Moustsen et al. 2011) and if larger sows gave birth to larger litters. The average parity of the measured sows was 3.2, ranging from Parity 1 to 10. Sows farrowed, on average, 8.8 days before measuring. Length, width, height and depth of ~40 hyper-prolific crossbred (Large White × Landrace) sows, in 10 production herds, were measured (Table 1). The sows were in a standing position on a level surface when measured. Length was measured with a carpenter’s rule as a straight line from snout to behind hind legs. Three measurements were taken and the average used in analysis. Depth, and width at the shoulders was measured using a specially developed calliper. Depth was measured in the middle section of the sow between the front and hind legs, from the dorsal to the ventral surface, and can be used as an estimate of the width of the sow’s body when lying. The height was measured using the carpenter’s rule. Number of liveborn and stillborn piglets were recorded. Data were analysed using generalized mixed models (SAS EG 7.1, SAS Institute Inc., Cary, NC, USA) with length, width, height and depth in turn as response variables, and parity group (1, 2 to 3, 4+) and total born (< or > than the median of the parity group) as explanatory variables. Herd was included as a random effect. In the statistical analysis, means were compared by Type 3-test. Length, width, height and depth increased significantly with increasing parity (P < 0.001), however, within parity group there was no difference in body dimensions between sows having litter size less or higher than the median of the group.

Table 1.  Litter size and body dimensions of 405 Danish crossbred sows in 2017. Mean ± s.e. and 5th to 95th percentiles (in italics)

It is important that housing facilities allow the sows to stand up and lie down unhindered and enables all piglets easy access to the udder. Therefore, knowledge of sow dimensions is important. The average litter size in Danish production herds has increased over the years. However, this study concluded that there was no significant correlation between the measured sow dimensions and litter size. In addition, sow dimensions were similar to a previous study (Moustsen et al. 2011). It is expected that recommendations based on Moustsen et al. (2011) will continue to ensure sows’ ability to stand up and lie down unhindered.