The confinement conundrum: what next for farrowing crates?

What are farrowing crates and why are they controversial? Are memories of welfare improvements 25 years ago preventing UK farmers from moving away from the crating of sows for as long as five weeks at a time? Have farrowing crates, which were first introduced more than half a century ago, had their day? If so, what might replace them? Josh Loeb investigates.