Porcine ear necrosis in weaned piglets : prevalence and impact on daily weight gain

Background Porcine ear necrosis (PEN) in pigs is characterized by a blue to black discoloration of the tip or margin of the ear followed by necrosis. The present study investigated the prevalence of PEN in a Belgian pig farm with PEN problems in nursery pigs, the effect of a mycotoxin detoxifier added to the feed on PEN prevalence, and the impact of PEN on the piglets' growth. Six consecutive batches of weaned piglets [565-751 piglets per batch, (n = 3898)] were included. For each weaning batch, the presence and severity of PEN during the nursery period (3-10 weeks of age) were recorded weekly. Average daily gain (ADG) was calculated by weighing 597 individual piglets divided over the six batches. Additionally different mycotoxins were measured in the feed using LC-MS/MS analysis, and to three randomly selected batches, a mycotoxin detoxifier (Mycofix (R) Plus 5E, Biomin) was added to the feed. Results At the end of the nursery period, 11.0-32.0% of the piglets in each batch were affected. The prevalence increased with the number of weeks post-weaning, especially from week 4 after weaning onwards. Mild, moderate, severe and very severe lesions represented 84.6%, 14.0%, 1.3% and 0.1% of all lesions, respectively. Different mycotoxins were present in the feed, but all at low concentrations. The mean ADG (+/- SD) for pigs without (n = 243) and with (n = 158) lesions was 391 g (+/- 71 g) and 394 g (+/- 65 g), respectively (P > 0.05). The ADG for mildly affected (387 g +/- 68 g) and moderately affected piglets (420 g +/- 44 g) was not significantly different (P > 0.05). The PEN prevalence in the batches without or with the mycotoxin detoxifier was 25% and 22%, respectively (P > 0.05). Conclusions Twenty-three percent of animals showed lesions at the end of the nursery. Affected pigs did not have a lower ADG compared to non-affected animals, which might be explained by the fact that most affected piglets only had mild lesions. The addition of a mycotoxin detoxifier did not influence the prevalence of PEN, possibly because of the low levels of mycotoxin contamination. Further research is warranted to assess the impact of more severe PEN lesions and the effect of control measures