NADIS surveillance veterinary surgeons record and report the quarterly figures for mortality from weaning to sale – whenever that may occur – in a defined population that currently is concentrated in the central/East Anglia region and in the North East where there are well documented differences in systems of management (e.g. East Anglia contain a higher proportion of straw based/outdoor sow systems with offsite rearing/finishing whereas slatted breeder feeder farms are more often seen in the North East.)

Pigs have been through a torrid time in the last ten years with PCV2, a major cause of loss. The advent of vaccines – albeit under restricted availability – in 2006/7 is generally accepted as having provided major benefits. The NADIS data collection began in the spring of 2007 just as vaccinated pigs were beginning to filter through the system and the BPEX subsidised vaccine programme took hold in spring of 2008 with vaccinated pigs coming through for slaughter in large numbers by the end of that year.

The pattern of mortality can thus be tracked over time (Graphs 1a & b).

Death rates were at their highest at the start of this period (Mid 2007) and whilst dropping dramatically later that year, rose back up in the winter/spring of 2008. There was then a marked decline through late 2008 and this improvement has been largely maintained at around 3.5 per cent total losses since then. However, many factors are in play on causes of death and a marked jump occurred in this last winter corresponding with the severe weather of Dec/Jan/Feb with clinical problems particularly in younger weaners widely reported at that time. It is disappointing to see that losses now are still ahead of those seen last year and might be attributable to:

1. Damage done to young pigs in the winter that is still working its way through the system
2. Reduced numbers of pigs weaned in winter (due to previously reported high preweaning losses especially in the outdoor sector) affecting calculation of percentages

Between management systems (Graph 2) looking at the current picture, death rates continue to be higher on slatted systems compared to those based on straw – a picture that reflects geographically (Graph 3) where East Anglia favours straw based systems.

There are only marginal differences between indoor and outdoor produced pigs (where outdoor derived pigs have slightly lower levels of loss) and very little difference between batch and continuous flow systems perhaps suggesting that the batch production either doesn’t give such benefits as might be expected or batch system management fails to take advantage of any potential benefits such system would be expected to have.

Graph 3 breaks data down by herd type. Breeder feeder and Nursery Finisher farms would be expected to have higher mortality recorded – the pigs are on site longer in these systems. Given the different populations monitored it may not be valid to simply add B/W or nursery to finisher only deaths, but it is worth noting that if this is done overall losses are around 6 per cent whereas for single site growing they are only 5 per cent.

There is also a fairly steady trend of increasing percentage loss with herd size (Graph 5) although no detail is collected to explain an almost doubling of loss between the smallest and largest sites monitored.