It is one of the main parameters recorded by NADIS monitoring veterinary surgeons during routine pig farm visits – it is thus possible to follow trends and examine patterns of production. Variations between herds can be vast. During 2010 the lowest level recorded has been 19 whereas the most productive herds have exceeded 28 pigs per sow per year.

The trend over time (graph 1) however identifies a remarkably stable picture. Apart from the summer/autumn period in 2008 where an inexplicable rise in productivity occurred, output has remained on average, between 22.5 and 23.5 pigs per sow per year for the monitored population for three years. It is encouraging to see no obvious drop in the winter and spring recently, despite previously reported high piglet mortality rates in the cold weather.

Graph 2 suggests that herds between 300 and 700 sows are the most productive, although larger herds are not far behind. Traditionally there has been a view that the smaller herds – particularly those below 100 sows – are staffed by owner/managers who spend disproportionate time looking after stock and reap the rewards in productivity. NADIS data currently does not support this supposition.

However, it has also historically been held that the weaner producer, who is totally reliant on numbers produced to make a profit, will tend to show higher sow output than breeder/feeders who make most profit in the finishing stages. This is supported by the NADIS data from breeder/weaner farms (graph 3) (those selling around 30kg weaners) but not of breeding only farms, which show very poor levels of production in the sampled population. Care must be taken here, as the number of breeding only farms surveyed is low.

With respect to management systems, outdoor herds have fared badly this year – probably reflecting the high winter mortality levels, and may relate back to the low productivity of breeding only farms, if these are concentrated in the outdoor sector. There is little difference in productivity of sows housed on straw and slats with the latter being slightly higher (graph 4). Batch farrowers are, however, recorded as being less productive than continuous flow farms, albeit by a small amount. This might correspond to the recognised pressure that batch systems bring on farrowing index, with higher wasted days in sow that need to be manipulated to fit within the service window.

Geographically, East Anglia has suffered low productivity this year compared to other areas (graph 5) which would again be consistent with outdoor production suffering in cold weather, there being a concentration of outdoor herds in this area within the surveyed population.