Asia pig farms expand – but nursery problems remain
by Dr. Steven McOrist, Scolexia P/L consultancy group - Australia, Hong Kong, Philippines firstname.lastname@example.org
Many pig farm systems across China and east Asia continue to expand, with more breeding pigs and improved litter sizes. This inevitably leads to higher numbers of piglets arriving at the weaner or nursery pig area.
For many years, these busy nursery areas have had high levels of illness and losses, due to the pig respiratory disease complex (PRDC). The PRDC losses have been reduced on most farms, with the successful usage of circovirus (PCV) vaccines in piglets, which control the effects of that immune-suppressive virus.
However, many farms still suffer high levels of nursery losses, often due to the effects of two other immune-suppressive viruses that are common in pigs across east Asia, namely porcine reproductive and respiratory syndrome virus (PRRS) and classical swine fever (CSF). Unfortunately, the available vaccines for these two viruses are not generally quite as effective as the leading PCV vaccines.
In a typical scenario, large to medium-sized farm systems in Asia operate with breeder, nursery and finisher units on a single farm site, in a region with many other similar farms (Figure 1).
Figure 1. Cluster of medium-sized pig farms in Asia region.
The farmer may have purchased many gilts in lines of modern pig breeds. Over the previous year, the mortality rate among groups of nursery pigs was high to very high (10 to 20 %), usually in the groups between 4 weeks and 10 weeks old.
Many of these pigs were noticed to have some nasal discharges (Figure 2) and coughing.
Figure 2. Nursery pig with pale nasal discharge.
Occasionally, several pigs would die in a group in a one-week period. Generally, the nursery pigs were dull and depressed with poor appetite. They were in poor body condition and were slow at growing to target weights (Figure 3).
Figure 3. Groups of dull nursery pigs with poor growth.
At necropsy of the dead pigs, a range of problems was noted, such as pneumonia with a mottled, tan colour to the lungs or patchy areas of firm consolidation pneumonia and pleurisy. These problems often persist for many months and do not respond to antibiotics.
This type of nursery PRDC problem remains common in China and on east Asian farms that have on-going infections and problems with PRRS virus strains. In the scenario illustrated here, the pigs are also...
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