A high number of second parity sows have farrowed over the past three months or so, and this is where the problems are occuring, says the report.

An investigation, using detailed farm records, has found that the fall in performance could be traced back to gilts that farrowed and reared their first litters during the summer of 2006. A presumed feed intake problem, because of the incredibly high temperatures, is thought to be responsible for the subsequent reduction in reproductive efficiency and 'second litter drop'.

Herd age structure anomalies also continue to feature prominently in the UK breeding herd and are a cause of low herd productivity. There were the inevitable service management problems and issues with on farm collection and use of AI.

In particular, time pressure on serving large groups of females in batch systems, especially those in bigger herds, were also thought to account for poor results.

Most batch systems require sows to be served inside a 7 to 10 day window, and that can create immense pressure on labour resources. This can lead to poor oestrus detection and inefficiencies in the service routine, resulting in higher returns and lower conception rates.

AI and service techniques could be improved on many units through training. A better understanding of sow management from weaning to mating could improve reproductive performance on most units.