title: Efficacy of controlled-release capsules containing monensin for the prevention of subclinical ketosis in pasture-fed dairy cows.
abstract: OBJECTIVE
  To determine the effectiveness of intra-rumenal controlled release capsules (CRC) containing 32 g of monensin administered pre-calving to reduce the cumulative incidence of subclinical ketosis (SCK) in mainly pasture-fed dairy cows.
  
  
  METHODS
  Cows (n=837) due to calve in the first 6 weeks of the spring calving period were enrolled from four commercial herds in the Waikato region of New Zealand in a blinded, randomised, negative-controlled field trial. Three weeks before the start of the calving period cows were randomly allocated to receive either no treatment (control) or a single CRC containing monensin and then blood sampled on two occasions, 7 days apart within 12 days following calving for measurement of concentrations of beta hydroxybutyrate (BHBA) in blood. Cows were diagnosed with SCK if the concentration of BHBA in blood in either of these samples was ≥1.2 mmol/L.
  
  
  RESULTS
  Fewer treated cows were diagnosed with SCK within 12 days post-calving than control cows (144/340 (42.4%) vs. 192/336 (57.1%); p<0.001). There was no interaction between treatment group and age, breed or herd of origin. From the final multivariable model it was estimated that treatment with CRC containing monensin reduced the absolute cumulative incidence of SCK by 17.9 (95% CI=9.2-25.8)% compared to no treatment.
  
  
  CONCLUSIONS
  Treatment with a CRC containing monensin>10 days prior to calving reduced the cumulative incidence of SCK of pasture-based dairy cows in commercial dairy herds within 12 days post-calving.
  
  
  CONCLUSIONS
  Administration pre-calving of an intra-rumenal bolus containing monensin can be considered as one of a range of management options for the control of SCK in early lactation.
authors.affiliation: a Cognosco , Anexa Animal Health , PO Box 21, Morrinsville , New Zealand.
authors.forename: C W R
authors.initials: CW
authors.lastname: Compton
authors.forename: L
authors.initials: L
authors.lastname: Young
authors.forename: S
authors.initials: S
authors.lastname: McDougall
mesh_terms: D000821:Animal Feed / Q000009:adverse effects* / Q000032:analysis; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000209:etiology / Q000517:prevention & control*; D003692:Delayed-Action Preparations; D004032:Diet / Q000662:veterinary; D007662:Ketosis / Q000517:prevention & control / Q000662:veterinary*; D008985:Monensin / Q000008:administration & dosage / Q000494:pharmacology*; D061209:Proton Ionophores / Q000008:administration & dosage / Q000494:pharmacology
chemical_list: D003692:Delayed-Action Preparations; D061209:Proton Ionophores; D008985:Monensin
keywords: Randomised; beta hydroxybutyrate; clinical trial; dairy cow; monensin; pasture; subclinical ketosis