14 September 2001

How best to tackle real threat to pig industry?

Post-weaning multi-systemic

syndrome and porcine

dermatitis and nephropathy

syndrome are proving as

great a threat to the pig

industry as foot-and-mouth

and classical swine fever.

Richard Allison reports from

an MLC and National Pig

Association seminar on

managing the diseases

VETS have come up with a raft of practical ideas to control PDNS and PMWS on-farm to ease producers three-year struggle against the diseases.

Norfolk producer Philip Richardson first observed both diseases on his unit 18 months ago and believes they are costing 10-15p/kg deadweight. Pigs are also taking an extra 20 days to reach slaughter, crowding finishing houses.

Mr Richardson tried various drugs, feed additives and management strategies, but to little avail. "Mortality has not improved and staff morale has been reduced."

In the worst case scenarios, depopulating the flat-deck area for a period of 2-3 months can help, said Barcelona-based pig vet Enric Marco. "This is a drastic measure, but it achieves spectacular results."

Using this practice reduced mortality on one Spanish unit last year. However, a second depopulation is planned because some disease remains.

But the high risk of re-infection and costs of depopulation and restocking puts off many producers, added Mr Richardson.

"Changing management and reducing stocking rates is not a cure, it is just reducing symptoms. There is a high level of uncertainty regarding cost-effectiveness of such measures and whether they are long lasting."

In Mr Richardsons experience, minimising mixing reduces mortality, but to implement this fully requires a 20% reduction in herd size or investment in extra buildings. In addition, this improvement was observed in summer and it may be different in winter.

In Spain, where PDNS and PMWS first appeared in 1997, a number of measures have been tried out to mitigate the diseases, said Mr Marco.

Control measures have three main aims – maintain herd health balance, avoid pathogen spread between animals and promote animals immune response.

Maintaining the health balance of the unit involves adopting an all in, all out system, with adequate cleaning of rooms between batches. "In one case, a 2500-sow unit introduced a three-site system with an all in, all out approach for the finishing barns. Mortality is now lower at 4-5%, but this is still too high," said Mr Marco.

East Anglia-based vet Roger Harvey stressed that failure to adopt an all in, all out system would expose the pig to pathogens from pigs previously in that accommodation.

Avoiding disease spread by changing from weekly to three weekly farrowing batch groups is also important, said Mr Marco. For each group, piglets should be weaned on the same day.

He also suggested minimising fostering of piglets and keeping it within two days of farrowing.

Avoiding mass injection treatments may also help because jabbing every pig will lead to increase mortality.

But there are many ineffective strategies which had been tried, according to Mr Harvey. These include the use of mould inhibitors, vaccination of piglets against porcine respiratory and reproductive syndrome (PRRS) and doing nothing.

REDUCINGMORTALITY

&#8226 Adopt all in, all out system.

&#8226 Lower stocking density.

&#8226 Good hygiene and cleansing.

&#8226 Reduce mixing.

&#8226 Minimise stress.