title: Post-weaning growth of beef heifers drenched with long- or short-acting anthelmintics.
abstract: OBJECTIVE
  To determine whether (i) the drenching practices of beef producers in the Central Tablelands of NSW utilising short-acting anthelmintics limit the post-weaning growth of heifers and (ii) a single weaning treatment of a long-acting anthelmintic improves post-weaning growth.
  
  
  METHODS
  Commencing at weaning, 20/100 heifers in each of five herds were injected four times at 90-day intervals with long-acting moxidectin to suppress gastrointestinal nematodes. In year 1 the balance was drenched using the owner's usual commercial practice with short-acting anthelmintics (5 herds) or left undrenched (1 herd). In year 2 the balance was drenched with long-acting moxidectin within 3 months of weaning (4 herds) or with short-acting drenches only (2 herds). At each visit live weight (LW) was recorded and a subsample tested for worm egg count (WEC) and plasma pepsinogen.
  
  
  RESULTS
  In year 1 by 3 and 6 months' post weaning, suppressed heifers were significantly heavier than the undrenched and short-acting groups, and by 12 months were 40 and 28 kg heavier, respectively. In year 2, the LW of the suppressed and long-acting heifers was not different, but by 3 and 6 months both groups were significantly heavier than the short-acting group and by 12 months were 22 kg heavier.
  
  
  CONCLUSIONS
  The post-weaning growth of beef heifers treated with short-acting drenches as adopted by Tablelands beef producers was slower than heifers drenched suppressively or with a single long-acting drench at weaning.
authors: Tablelands Livestock Health and Pest Authority (now Central Tablelands Local Land Services), Bathurst, NSW, Australia. eppo.jeff@gmail.com.
authors: J
authors: J
authors: Eppleston
authors: Tablelands Livestock Health and Pest Authority (now Central Tablelands Local Land Services), Bathurst, NSW, Australia.
authors: B
authors: B
authors: Watt
authors: New South Wales Department of Primary Industry, Orange, NSW, Australia.
authors: R
authors: R
authors: van de Ven
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D001835:Body Weight / Q000187:drug effects*; D002417:Cattle / Q000254:growth & development / Q000502:physiology*; D002418:Cattle Diseases / Q000517:prevention & control; D005260:Female; D016014:Linear Models; D018942:Macrolides / Q000494:pharmacology*; D009517:New South Wales; D010270:Parasite Egg Count / Q000662:veterinary; D014886:Weaning
chemical_list: D000871:Anthelmintics; D018942:Macrolides; C027837:moxidectin
keywords: anthelmintics; beef cattle; gastrointestinal nematodes; productivity