Effect of prepartum intramammary treatment with pirlimycin hydrochloride on prevalence of early first-lactation mastitis in dairy heifers.
OBJECTIVE
To determine whether prepartum intramammary treatment of dairy heifers with pirlimycin hydrochloride would reduce the prevalence of intramammary infection (IMI) and lower the somatic cell count (SCC) during early lactation or improve 305-day mature equivalent milk production.


METHODS
Prospective clinical trial.


METHODS
183 Holstein-Friesian heifers (663 quarters) from 2 dairy farms.


METHODS
Heifers were assigned to treatment and control groups. Treated heifers received a single 50-mg dose of pirlimycin in each mammary quarter approximately 10 to 14 days prior to parturition. Prepartum mammary gland secretions and postpartum milk samples were collected for bacterial culture. Postpartum milk samples were also collected for determination of SCC or California mastitis testing and were tested for pirlimycin residues. Mature equivalent 305-day milk production data were recorded.


RESULTS
Treated heifers in herd A had a higher overall cure rate, higher cure rates for IMI caused by coagulase-negative staphylococci (CNS) and Staphylococcus aureus, lower SCC, and lower prevalence of chronic IMI, compared with control heifers. Treated heifers in herd B had a higher overall cure rate and cure rate for IMI caused by CNS, compared with control heifers, but postpartum California mastitis test scores and prevalence of chronic IMI did not differ between groups. Mature equivalent 305-day milk production did not differ between herds or treatment groups. No pirlimycin residues were detected in postpartum milk samples.


CONCLUSIONS
Results suggest that prepartum treatment of dairy heifers with pirlimycin may reduce the prevalence of early lactation IMI, particularly IMI caused by CNS, without causing pirlimycin residues in milk.
Middleton
John R
JR
Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA.
Timms
Leo L
LL
Bader
G Ryan
GR
Lakritz
Jeffrey
J
Luby
Christopher D
CD
Steevens
Barry J
BJ
D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D002417:Cattle; D002452:Cell Count / Q000662:veterinary; D002981:Clindamycin / Q000031:analogs & derivatives* / Q000627:therapeutic use; D004350:Drug Residues / Q000032:analysis; D005260:Female; D008321:Mammary Glands, Animal / Q000382:microbiology*; D008414:Mastitis, Bovine / Q000453:epidemiology* / Q000517:prevention & control; D008892:Milk / Q000737:chemistry / Q000166:cytology / Q000382:microbiology; D011247:Pregnancy; D011446:Prospective Studies; D011897:Random Allocation; D013210:Staphylococcus / Q000187:drug effects / Q000254:growth & development; D013291:Streptococcus / Q000187:drug effects / Q000254:growth & development; D016896:Treatment Outcome
D000900:Anti-Bacterial Agents; D002981:Clindamycin; C034093:pirlimycin