title: Prevalence of mastitis in dairy heifers and effectiveness of antibiotic therapy.
abstract: Dairy heifers were treated 0 to 90 d, 90 to 180 d, or 180 to 270 d prepartum with one of five different antibiotic products to determine the best time and with which product they should be treated prior to calving. Two hundred thirty-three heifers were included in the study. At the initial sampling, 56.5% of quarters were infected with some type of organism and 15.4% of quarters were infected with Staphylococcus aureus. Treatments included a cephapirin dry cow product, a penicillin-novobiocin dry cow product, a penicillin-streptomycin dry cow product, an experimental dry cow product containing tilmicosin, and a cephalonium dry cow product not available in the United States. Cure rates for the five antibiotic products indicated that all were equally effective against Staph. aureus and all were significantly more effective than the spontaneous cure rate observed in untreated control quarters. No differences in efficacy were observed due to the different treatment times prepartum. However, fewer new Staph. aureus infections occurred after treatment in the group treated at 180 to 270 d prepartum, indicating that treatment in the third trimester will reduce the chances of new intramammary infections occurring after treatment and persisting to calving.
authors.affiliation: Mastitis Research Laboratory, Hill Farm Research Station, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Homer 71040, USA. wowens@agctr.lsu.edu
authors.forename: W E
authors.initials: WE
authors.lastname: Owens
authors.forename: S C
authors.initials: SC
authors.lastname: Nickerson
authors.forename: R L
authors.initials: RL
authors.lastname: Boddie
authors.forename: G M
authors.initials: GM
authors.lastname: Tomita
authors.forename: C H
authors.initials: CH
authors.lastname: Ray
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D002417:Cattle / Q000502:physiology; D002514:Cephapirin / Q000008:administration & dosage / Q000627:therapeutic use*; D004338:Drug Combinations; D005260:Female; D008414:Mastitis, Bovine / Q000188:drug therapy* / Q000453:epidemiology*; D009675:Novobiocin / Q000008:administration & dosage / Q000627:therapeutic use; D010406:Penicillins / Q000008:administration & dosage / Q000627:therapeutic use; D011247:Pregnancy; D015995:Prevalence; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000453:epidemiology / Q000662:veterinary*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000472:pathogenicity; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D004338:Drug Combinations; D010406:Penicillins; D009675:Novobiocin; D002514:Cephapirin