Clinical Bovine Mycoplasmal Mastitis

Abstract

The California Dairy Herd Improvement Association records of 29 California dairies which experienced clinical mycoplasmal mastitis between January 1975 and December 1977 were examined and compared to the records of selected control herds. A 15-fold greater risk of clinical mycoplasmal mastitis was found among large herds as compared to small herds. On average, herds with clinical mycoplasmal mastitis culled 5 % more cows than did control herds (33 % vs 28 %). No difference was found in average milk production. These findings compare closely with the findings of a previous report where infected herds were identified by the presence of pathogenic mycoplasma in bulk tank milk. The similarity of results support the use of frequent bacteriologic culture of bulk tank milk as a routine surveillance strategy for mycoplasmal mastitis in endemic areas. The similarity of results also supports the use of routine clinical diagnostic data in the study of the epidemiology of diseases of veterinary importance.

Sammendrag

Kontrolforeningsdata for 29 californiske malkekvægsbesætninger, hvori kliniske udbrud af mycoplasma mastitis forekom i perioden januar 1975 – december 1977, blev analyseret ved sammenligning med data fra „matchede” kontrol-besætninger. En 15-gange forøget risiko for sygdommen fandtes blandt store besaetninger (over 350 års-køer) sammenlignet med mindre besaetninger (under 350 års-køer). Sygdomsramte besaetninger udsatte i gennemsnit 5 %-enheder flere køer end kontrol-besaetningerne (33 % vs. 28 %). Der var ingen forskel i de gennemsnitlige ydelsestal. Disse resultater stemmer helt overens med resultaterne af en tidligere publiceret undersøgelse, hvor sygdomsramte besaetninger blev identificeret ved hjælp af indsamlede tankmaelksprøver. Dette understøtter anvendelsen af sådanne prøver i overvågningsprogrammer for mycoplasma-mastitis, ligesom det understøtter anvendelse af data fra indsendte diagnostiske prøver i forbindelse med undersøgelser af epidemiologiske forhold vedrørende sygdomsproblemer i veterinaer praksis.