title: Effects of a monensin controlled-release capsule or premix on attenuation of subacute ruminal acidosis in dairy cows.
abstract: The effects of monensin, administered either as a controlled release capsule (CRC) or a premix, on attenuating grain-induced subacute ruminal acidosis (SARA) and on ruminal fermentation characteristics in Holstein cows receiving a total mixed ration were investigated in two experiments. In both experiments, six multiparous, rumen-fistulated Holstein cows were used in a two-treatment, two-period crossover design with 6-wk periods. In Experiment 1, treatments were either a monensin CRC or a placebo CRC. In Experiment 2, treatments were either a monensin premix or a placebo premix. In both experiments, at the beginning of wk 4 SARA was induced in experimental cows for a 10-d period with a grain challenge model, and ruminal pH was measured continuously using indwelling pH probes. The administration of monensin either as a CRC or a premix had no effect on ruminal pH characteristics. Neither monensin CRC nor premix had an effect on ruminal volatile fatty acid concentrations, but reduced the acetate:propionate ratio. Monensin premix-treated cows were observed to have increased milk yield, largely as a result of a higher dry matter intake in monensin-treated cows compared to control cows. Milk fat content and yield were lower in monensin-treated cows compared to placebo-treated cows during SARA. In conclusion, there is no evidence that monensin was efficacious in raising ruminal pH during SARA under the conditions employed in this study.
authors.affiliation: Department of Animal and Poultry Science, University of Guelph, Guelph, ON, Canada N1G 2W1.
authors.forename: T
authors.initials: T
authors.lastname: Mutsvangwa
authors.forename: J P
authors.initials: JP
authors.lastname: Walton
authors.forename: J C
authors.initials: JC
authors.lastname: Plaizier
authors.forename: T F
authors.initials: TF
authors.lastname: Duffield
authors.forename: R
authors.initials: R
authors.lastname: Bagg
authors.forename: P
authors.initials: P
authors.lastname: Dick
authors.forename: G
authors.initials: G
authors.lastname: Vessie
authors.forename: B W
authors.initials: BW
authors.lastname: McBride
mesh_terms: D000138:Acidosis / Q000188:drug therapy / Q000662:veterinary*; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy*; D003692:Delayed-Action Preparations / Q000008:administration & dosage; D004032:Diet; D004435:Eating; D005232:Fatty Acids, Volatile / Q000032:analysis; D005260:Female; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D007785:Lactose / Q000032:analysis; D008055:Lipids / Q000032:analysis; D008892:Milk / Q000737:chemistry; D008894:Milk Proteins / Q000032:analysis; D008985:Monensin / Q000008:administration & dosage*; D012417:Rumen / Q000737:chemistry; D013272:Stomach Diseases / Q000188:drug therapy / Q000662:veterinary*
chemical_list: D003692:Delayed-Action Preparations; D005232:Fatty Acids, Volatile; D008055:Lipids; D008894:Milk Proteins; D008985:Monensin; D007785:Lactose