Free farrowing pens (pens) improve the welfare of sows but may increase sow activity and negatively influence piglet production, according to Michala Melisová and colleagues at the Institute of Animal Science in Prague-Uhríneves.

The aim of their study - published in Journal of Animal Science - was to assess the effect of pens and crates on sow postural changes, piglet trapping, sow responses to piglet screams, piglet mortality and piglet bodyweight gain.

It was predicted that provision of greater space (in pens) would increase not only the frequency of sow postural changes and the probability of trapping but also sow responses to the screams of piglets; thus, the outcome would be no differences in fatal piglet crushing or overall mortality between the housing systems.

Sows were randomly moved to either a farrowing pen (n=20) or farrowing crate (n=18). Sow behaviour was recorded and analysed for 72 hours from the birth of the first piglet (BFP). Sow postural changes included rolling from a ventral to lateral position and vice versa and going from standing to sitting, standing to lying, and sitting to lying.

Occurrences of piglet trapping and sow responsiveness to real crushing situations were analysed. Sow responsiveness was assessed in response to audio playbacks (PB) of piglet screams on day 3 post-partum (48 to 72 hours after BFP; PB crush calls) and real piglet crushing during the first 72 hours after BFP (real crush calls).

Piglet bodyweight gain was estimated 24 hours after BFP, piglet bodyweight was recorded at weaning, and piglet crushing and piglet mortality were recorded during the 72 hours after BFP.

Data were analysed using PROC MIXED and PROC GENMOD of SAS.

Sows in pens showed more postural changes (P=0.04) and tended to have a greater incidence of piglet trapping (P=0.07) than those in crates.

Sow response to PB crush calls was greater in pens (P=0.04) but did not differ for real crush calls between pens and crates (P=0.62).

There was no effect on the probability of piglet crushing (P=0.38) and mortality (P=0.41) during the 72 hours after BFP nor in piglet mortality at weaning (P=0.81) between pens and crates.

Piglet bodyweight gain 24 hours after BFP (P=0.01) and piglet bodyweight at weaning (P=0.02) were greater in pens.

Sows in pens showed more postural changes and tended to trap more piglets, noted Melisova and colleagues, but the response to real crush calls did not differ between the two housing systems. Nevertheless, there was no increase in piglet crushing or mortality in pens, which might be influenced by the better piglet body condition observed in pens, which in turn could influence their ability to avoid crushing by the sow.

Reference

Melisova M., G. Illmann, H. Chaloupkova and B. Bozdechova. 2014. Sow postural changes, responsiveness to piglet screams, and their impact on piglet mortality in pens and crates. J. Anim. Sci. 92(7):3064-3072. doi: 10.2527/jas.2013-7340

July 2014