STUDY ON BOVINE SUB-CLINICAL-MASTITIS ON FARM CONDITION WITH SPECIAL EMPHASIS ON ECONOMIC EFFECT AND ANTIBIOGRAM OF THE CAUSATIVE BACTERIA

Abstract

The study was conducted to find out the prevalence of subclinical mastitis (SCM) and its effects on milk yield in dairy cows at the Sylhet govt. Dairy Farm (SGDF) and Local Farms of Sylhet (LFS) during the period of July2014 to June2015. These farms are selected to assess the predominant types of bacteria involved in causing sub-clinical mastitis and to know the in vitro antibiotic sensitivity spectrum of these bacterial isolates against the commonly used antibiotics and to study the economic effects due to SCM.Use of California Mastitis Test (CMT) for the detection of sub clinical mastitis showed 42 samples were test positive out of 100, among which +(Trace) 22.0%, ++(Distinct) 12.0%, +++(Strong) 3.0%, ±(Doubtful) 5.0%. 48 samples were negative.Bacteriological examination of milk samples of 100 milch cows (400 quarters) revealed that 42 cows (42.0%) had suffering from SCM with different bacterial infection with 95% confidence limit was 32.1574-51.8426.Among 42 positive samples 31 (31.0%) cows had mono-bacterial infection and 11 (11.0%) cows had mixed bacterial infections. Statistical analysis of the result of single and mixed bacterial infection in the milk of apparently healthy milch cows revealed that the single infection was significantly (P < 0.05) higher than mixed bacterial infection. Of the 31 mono-bacterial isolates, of which 23 (23.0%) isolates were Staphylococci, 3 (3.0%) isolates were Escherichia coli, 5 (5.0%) isolated Streptococcus spp. (Table 3). The 11 (11.0%) cows had mixed infection, of which 5 (5.0%) had Staphylococcus spp. + Streptococcus spp., 3 (3.0%) had E. coli + Staphylococcus spp., and 3 (3.0%) had Streptococcus spp. +E. coli. Of 42 positive cases of SCM Staphylococcus spp. isolated from 23 samples. Among these 23 positive samples 13 obtained from SGDF (37.14%) and 10 obtained from LFS (15.38%). Escherichia coli isolated from 3 samples. Among these 3 positive samples 3 obtained from LFS (4.62%). Streptococcus spp. isolated from 5 samples. Among these 5 positive samples 1 obtained from SGDF (2.86%) and 4 obtained from LFS (6.15%). Of the 11 mixed infections, 5 were Staph. + Strep. Among these 5 positive samples 1 obtained from SGDF (2.86%) and 4 obtained from LFS (6.15%). Staph. + E. coli obtained from LFS that is 3 (4.62%). Strep. + E. coli combination obtained from 3 samples also from LFS. The overall mean milk yield of dairy cows who had bacterial infection (SCM) reduce from 7.7 litre to 6.2 litre i.e. - 1.50 litre/cow/day. From the antibiotic sensitivity test of sub-clinical mastitis,the result showed that ceftriaxone, ciprofloxacin and gentamicin are the best drug for treating sub-clinical mastitis, though these antibiotics showed maximum sensitivity to the organism responsible to cause sub-clinical mastitis.