More highlights from the IPVS Congress in South Korea

Tuesday, April 2, 2013

More than 1,000 papers were presented at the 22nd IPVS Congress last June. A further sample of those that caught the author's eye

by ERNEST SANFORD

In the last issue of Better Pork, I covered some of the "Take Homes" gleaned from papers presented at the 22nd IPVS Congress held in Korea in June 2012. In this issue, I'll finish off my review of papers that caught my attention at the congress.

Effect of different castration days on growth performance of nursery pigs
– Jang JC, et al., Pg 148
Background. Although the title says "nursery" pigs, the investigators actually looked at the difference in growth in nursing pigs (not nursery pigs) castrated at one day of age versus pigs castrated at three days of age.
Results. Pigs castrated at one day of age had a growth check from three days of age (i.e. two days post-castration). Piglets castrated after three days of age had growth similar to female pigs (i.e. no growth check).
Take Home. Castrate pigs after three days of age.

Effect of the restricted movement of the piglets (cross-fostering) on the weight at weaning in an intensive pig production farm
– Olivares A, et al., Pg 150
Background. This study investigated what happens if cross-fostering were not done after piglets were 12 hours old.
Results. By not doing any cross-fostering 12 hours after birth, there was a significant weight gain at weaning over pigs that were cross-fostered after 12 hours of age in two of three replicates and there was reduced mortality at weaning in all three replicates.
Take Home. Consider cross-fostering piglets only up to 12 hours after birth.

Targeting pig producers with the highest use of antibiotics in Denmark: effect on consumption and choices of antimicrobials
– Andreasen M, et al., Pg 202
Background. In July 2010, Denmark introduced the "Yellow Card" scheme, which targets producers with the highest use of antibiotics in Denmark. Antibiotic usage is measured by calculating the animal daily dose (ADD) per 100 animals over nine months. Current limits that will trigger the Yellow Card are:
- 5.2 ADD/100 animal days for sows and piglets
- 28 ADD/100 animal days for weaners
- 8 ADD/100 animal days for finishers
When any of these levels are exceeded, the producer is issued a Yellow Card and ordered to work with the herd veterinarian to institute management procedures that aim to reduce antibiotic usage. If, after a period of time, the levels are not reduced below those listed above, a Red Card is expected to be issued. The Red Card initiative has not been decided upon yet, so no Red Cards have been issued so far. It is expected that, on being issued a Red Card, the producer will have to reduce the herd size to be compliant with the regulations.
The researchers investigated the before-and-after picture of antibiotic usage one year after implementation of the Yellow Card scheme in Denmark.
Results. There was a 12.5 per cent reduction in antibiotic consumption in the last half of  2010 versus the last half of 2009. A large part of the reduction was due to reduced whole herd medication after introduction of the Yellow Card scheme.
Take Home. One year after the introduction of the Yellow Card system in Denmark, there was a marked reduction in use of antibiotics.

Pooling of fecal samples for quantitative assessment of Lawsonia intracellularis
excretion levels
– Pedersen KS, et al., Pg 284
Background. Fecal samples were pooled up to 10:1 from 162 growing pigs without clinical signs of diarrhea. Pigs were in a single room in pens containing 12 to 21 pigs per pen. Pooled fecal samples were tested for Lawsonia intracellularis by qPCR.
Take Home. Pooling 10 fecal samples per pen provided an acceptable result for diagnostic assessment of Lawsonia intracellularis excretion at the pen level.

A case control study of ear necrosis
– Park J, et al., Pg 131
Background. In this study, bacterial culture and histological examinations of ear necrosis lesions were used to determine the causative agents of porcine ear necrosis. Farm-level risk factors were also investigated. From a convenience selection of 11 case farms and 14 control farms visited by the researchers, tissue biopsies and oral swabs were taken from pigs in early, middle and late stages of ear necrosis. A clinical examination was performed on each pig and samples were cultured for Staphylococcus aureus, S. hyicus and spirochaetes.
Results. The mean ages of early, middle and late stages of pigs with ear necrosis were 6.6 weeks of age (WOA) with a range of three to 12 WOA, 7.9 WOA with a range of five to 13 WOA and 10 WOA with a range of five to 16 WOA, respectively. Prevalence of ear necrosis was 31.6 per cent, 44.2 per cent and 54.8 per cent for early, middle and late stages.
Ear necrosis starts at the epidermal surface, then progresses more deeply into the ear tissue and not as a subcutaneous vascular lesion. S. aureus and S. hyicus were found 88.6 per cent and 68.6 per cent of the time, respectively. A few spirochaetes were seen histologically when special stains were applied, but spirochaetes were not isolated. The authors speculated that ear necrosis may be initially started by toxins released by staphylococci, leading to damage on the surface of the ear. Ear necrosis and ear biting are closely associated. Bitten ears may attract chewing by pen mates, resulting in trauma leading to secondary bacterial infection and more severe lesions.
Take Home. Ear necrosis is a multifactorial disease starting with damage to the surface of the ear and then progressing more deeply into the ear tissue. Toxins from S. aureus and/ or S. hyicus could possibly initiate damage to the ear surface. Ear biting then promotes further damage and more severe lesions.

Epidemiological evaluation of air filtration systems for PRRSV in large sow herds in a swine-dense area in North America
– Alonso C, et al., Pg 293
Background. The effectiveness of air filtration systems in 20 filtered and 17 nonfiltered control herds in preventing PRRS outbreaks in large sow herds was evaluated in a retrospective study between October 2004 and June 2011.
Take Home. PRRSV outbreaks were four times higher in control (nonfiltered) sow farms than in filtered farms.

These, of course, are only a very few of the more than 1,000 papers presented at the IPVS in Korea, but they were some of the leading ones that caught my attention. The next IPVS Congress is closer to home, in Cancun, Mexico, in 2014. BP

S. Ernest Sanford, DVM, Dip. Path., Diplomate ACVP, is a swine specialist with Boehringer Ingelheim Vetmedica (Canada) in Burlington. Email: ernest.sanford@boehringer-ingelheim.com