By Robert Knox
The farrowing crate was introduced over 50 years ago to improve the management of sows and survival of pigs in the litter. Sows in loose farrowing pens lost more pigs to crushing and so the crate was designed to provide space for the sow but to limit the accidental crushing of pigs when the sow sat or laid down. Additionally, the crate has been helpful for producers for individually feeding sows, providing farrowing assistance, processing litters, removing feces, and providing cooling for the sow and heating for the pigs.
As litter sizes have dramatically increased over years to where sows give birth to 14 to 17 live pigs, new challenges have arisen as producers have been faced with lower birthweights, increased stillborns and greater pre-wean mortality. There is greater attention on stillborns attributed to a longer duration of farrowing and the loss of weak pigs in the days after farrowing.
At the same time, societal pressures and public awareness on the housing of sows in crates have resonated in different places around the world to enable passage or proposals for legislation to limit or eliminate the use of the farrowing crate for sows.
For those who want to keep and those who want to eliminate the crate, the intent is the same; to improve the welfare of the sow and the pigs. This is where it gets complex. The standard farrowing crate provides sow and pig space to optimize management. But criticisms of its use include its failure to let the sow move freely and turn around, express normal behaviors at farrowing, and limits bonding with the litter. There is also speculation that these issues may relate to longer duration of farrowing, stillborns, and weak pigs.
Alternative farrowing systems are evolving to address these issues and include the use of temporary crates (TC), and free farrowing pens (FFP). The TC allows for the use of the crate (or modified crate) for a few days before and days after farrowing and prevents the sow from turning around, before providing more space when a swing gate or expandable side is opened. The FFP is a modified pen with many design possibilities but does not include the use of a crate and so the sow can always turn around. With the FFP, sows may have their own pen in a farrowing room or may have their individual pen inside a group pen with straw-bedding. In some systems, the individual pen may be removed in mid-lactation to allow group mixing.
The design features for any of the systems could include modifications in size of crate or pen, and include combinations of slanted walls, solid and slatted floor areas, feeding and dunging areas, straw dispenser, creep area, and protection bars.
The alternative systems can be successful, but can be challenging for producers for costs, space, design, and management. To date, for the FFP, sow behaviors are more normal, pig growth is similar, but piglet mortality is increased. The TC meets most welfare requirements with limited days of crating, and does not greatly increase mortality in most studies.
As might be expected, the reports on critical production measures are not always clear. The alternative systems clearly provide the sows more freedom in movement and in expression of natural behaviors during farrowing and lactation. But despite this freedom, limited benefits to the sow, piglet and producer can be substantiated.
Despite the uncertainty, some conclusions have been drawn. Piglet mortality is generally lowest in crates, and may slightly increase with the expanding size of the temporary crates, and increases with use of free farrowing pens. Further, the different systems do not clearly show effects on duration of farrowing and stillborns. What is next will likely involve more controlled data on system comparisons, new exploration for system design, testing days of crating, and measures for stress and behaviors that can be linked to welfare and production.
Robert V. Knox is a Swine Extension Specialist, Department of Animal Sciences, University of Illinois.