Ostertagia ostertagi is the most common and economically important parasite in cattle . Also known as the brown stomach worm , it is estimated to cost the U . S . cattle industry $ 2 billion peryear due to lost productivity and increased operating expenses .
“ On beef and dairy operations , we ’ re not seeing the traditional signs of worms , such as skinny animals with rough hair coats , anymore ,” said Stephen Foulke , DVM , Boehringer Ingelheim . “ Instead , internal parasite infections manifest as poor productivity , including reduced feed intakes , slower growth rates , delayed breeding , decreased milk production and depressed immune responses .”
Studies show that a brown stomach worm infection can reduce weight gain by up to 20 pounds , whereas milk production can see a decrease between two and five pounds per day .
How do herds become infected ?
Unlike other stomach worms , the brown stomach worm has the unique ability to penetrate the lining of the abomasum and become dormant , so it can survive during weather that ’ s too cold or too hot . When conditions improve , the larvae can emerge all at once , causing severe inflammation and irritation , reduced feed intake and sometimes even death .
Dr . Foulke breaks down the basic life cycle :
• Adult parasites lay eggs in the gastrointestinal tract of cattle .
• Eggs are expelled from the cattle through feces .
• Eggs hatch and develop into infected larvae .
• The infected larvae crawl onto the grass that cattle graze on .
• Larvae are ingested by cattle .
54 • OCTOBER 2020