Drought Surviving Parasites Will Make Fall Deworming Of Cattle Critical

STOCKTON, MO.
   Although it will take some time for the grasses in southwest Missouri to recover from the drought, there is one thing the will resume development quickly, parasites.
   One of the most important internal parasites of cattle, Ostertagia, has the mechanism to avoid adverse weather conditions according to Dona Goede, livestock specialist, University of Missouri Extension.
   “Like our cool season grasses, Ostertagia, will become dormant under hot and dry conditions but will resume development as the weather moderates. This increase in worms will limit the ability of the cattle to recover this fall if producers don’t treat their cattle,” said Goede.
   Adult Ostertagia graze the lining and cause irritation and fluid loss, interfering with the digestive function of the stomach. Dyspepsia or “heartburn” results so that feed is not tolerated well.
   Feed conversion for weight gain, body maintenance, reproductive fitness and milk production is then compromised.
   According to Goede, Ostertagia produce large numbers of eggs that contaminate pastures which can lead to increasing reinfection and increasingly greater numbers of worms in cattle in the fall.
   “Poor nutrition along with grazing patterns that enhance reinfections will make fall deworming critical for many herds,” said Goede.
   Dewormers that kill only adult parasites – like levamisole and morantel – can be used effectively in the fall.
   A dewormer that will kill adults and larva – like albendazole, fenbendazole, and oxfendazole and ivermectin will also be effective but will usually cost more than the ones that kill adult parasites only.
   Pour-ons and medicated feed blocks may be used to provide alternative and supplemental deworming formulations.
   “Effective and timely use of parasite control can be critical to overcoming added stresses of drought for maintaining or increasing condition as winter approaches,” said Goede. Δ