INCIDENCE OF Staphylococcus aureus AND Streptococcus agalactiae IN MILKS SUBMITTED TO CALIFORNIA MASTITIS TEST (CMT) BY THE HOTIS AND DIRECT BACTERIOLOGICAL METHODS
|Carlos Pedraza G.1, Gastón Alegría R.2, Luis Barrales V.3 y Fernando Silva F.4|
A study was carried out in order to detect the incidence of mastitis in six dairy farms of Santiago Province, Chile. The California mastitis Test (CMT) was applied to a total of 1.088 quarters and it was found that 84.2% of cows and 61.76% of quarters were affected by subclinical mastitis.
Of the affected quarters 34.52% were classified as CMT traces, 22.47% as CMT1; 20.38% as CMT2; 20.68% as CMT3 and only 1.93% corresponded to clinical mastitis. the direct bacteriological method and the Hotis test were confronted by considering 418 samples of milks.
Hipothesis test for binomial proportions was considered in a iterative way. This test indicated that only 65% of the time both methods yielded the same results (a=0.05).
The Hotis test was highly efficient to identify Streptococcus agalactiae but not for the identification of Staphylococcus aureus. In a high percentage of samples classified as negative by the direct bacteriological method, the Hotis test detected the presence of S. agalactiae.
|1Méd. Vet., Programa Producción de Leche, Estación Experimental La Platina, Instituto de Investigaciones Agropecuarias (INIA), Casilla 5427, Santiago, Chile. |
2Méd. Vet., Depto. de Salud e Higiene Animal, Facultad de Medicina Veterinaria. Universidad de Chile, Santiago.
3Ing. Agr., M. S., Oficina de Estadística, Estación Experimental La Platina, Instituto de Investigaciones Agropecuarias (INIA), Casilla 5427, Santiago, Chile.
4Egresado del Depto. Autónomo de Probabilidades y Estadistica de Universidad Católica de Chile, Santiago.