Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5803191 | Veterinary Parasitology | 2014 | 6 Pages |
â¢Presence of antibodies against gastrointestinal nematodes are described from calves on a ranch in southeastern Alberta, Canada over three consecutive years.â¢A greater number of calves were positive for antibodies than were positive for eggs in faeces.â¢Precipitation was different among the three years and appears to have had a profound effect on proportion of calves positive for both antibodies and for faecal eggs.
Sera from calves originating on a 17,000Â ha ranch in southeastern Alberta, were collected over three consecutive years (2008-2010) at weaning and analysed for the presence of anti-Ostertagia antibodies using the SVANOVIR®Ostertagia ostertagi-Ab ELISA kit. Faecal samples taken at the same time were analysed for presence of nematode eggs using the modified Wisconsin faecal flotation technique. Mean optical density ratio (ODR) values for all calves were similar in 2008 and 2010 while the 2009 values were significantly higher. Similar cumulative frequency distribution profiles were found for 2008 and 2010 while the 2009 profile had an increased number of values in the higher bin categories. This pattern indicates higher nematode transmission on pasture in 2009. There was no significant difference in ODR values between egg positive and egg-negative calves and no significant correlation was detected between individual ODR values and faecal egg output. Significantly higher ODR values in 2009 appear contradictory to general assumptions about the ecological requirements of larval development, as 2009 was a relatively dry year. However, examination of weather data identified 5-6 rainfall events that may have resulted in episodic enhanced survival of nematode larvae.