Bacteriological studies on pathogens causing sub-clinical mastitis holstein friesian dairy cows in assiut governorate : with 3 tables

الملخص EN

The study was conducted on 110 Holstein-Friesian dairy cows suffering from recurrent sub-clinical mastitis.

Screening of 110 milk samples, pooled samples, by using of both field tests (California Mastitis Test and modified Whiteside Test), revealed that 35 and 37 milk samples showed positive by both tests, respectively.

These positive samples were examined bacteriologically on general and specific enriched media the isolated bacterial strains (103 isolates) resembled two categories: contagious bacteria 37 isolates (35.92%) and environmental bacteria 66 isolates (64.08%).

Thirty four (97.14%) milk samples showed mixed infection, where most of them 20 milk samples (57.14%) were infected with triple infection.

The isolated contagious strains were Staph, aurous 17 (16.5%), Strept.

galactic 11 (10.68%), Corynebaterium spp.

8 (7.77%) and Strept.

dysgalactia 1 (0.97%), while the environmental bacteria were Enterobacter aero genes 13 (12.62%), Enterococcus facials and E.

coli 11 (10.68%) for both, Strept.

equi subsp.

zooepidemicus 7 (6.8%), Staph, saprophytic us 5 (4.85%) and other strains with less proportions were isolated where the most highly pathogenic of them was E.

coli O157 (1.94%).

Antimicrobial susceptibility testing reveled that all isolated strains were sensitive to ciprofloxacin and gentamycin with percentage 100% and 80.84%, respectively.