Studies on etio-diagnostic, micronutrient status and chemotherapeutic aspects of bovine sub-clinical mastitis
Abstract
The present investigation was carried out on 322 quarter milk samples, to study the prevalence and etiology of sub-clinical mastitis (SCM) in 85 apparently healthy cows, to evaluate the comparative sensitivity of some indirect mastitis detection tests and some soluble biomarkers of mastitis, to ascertain the micronutrient status with respect to serum copper and zinc status in mastitic cows and to evaluate therapeutic efficacy of ascorbic acid (an antioxidant) in bovine sub-clinical mastitis. The prevalence of SCM was recorded to be 60 per cent and 47.51 per cent animalwise and quarterwise, respectively. The prevalence of disease was highest in crossbred cows (72.30%) as compared to local Hariana cows (20.00%). On the basis of International Diary Federation criteria, 39.13, 8.38 and 6.21 per cent quarters were found to have sub-clinical, latent and non-specific mastitis, respectively. Of 166 isolates, Staph. epidermidis (43.37%) was the predominant organism followed by Staph. aureus (27.10%), Str. agalactiae (10.84%), Str. dysgalactiae (10.24%), Str. uberis (3.61%), Corynebacterium spp. (3.61%) and Ps. aeruginosa (1.20%). The highest sensitivity, specificity and accuracy for the detection of SCM, was attributed to LDH-assay (97.82%, 98.14% and 98.00%) followed by Spot TIA (86.95%, 92.59% and 90.00%), Mamp test (76.08%, 87.03% and 82.00%) and SCC (71.73%, 81.48% and 76.74%).
Serum concentrations of both copper and zinc were found to be significantly lower in mastitic cows (0.46 ± 0.12 μg/ml and 0.76 ± 0.05 μg/ml) as compared to healthy controls (0.913 ± 0.051 μg/ml and 1.18 ± 0.16 μg/ml). There was no significant effect of type of mastitis or even the type of mastitogenic organisms on the level of deficiency of these trace elements, although only a marginal deficiency of zinc was observed in latent and non-specific mastitis. The highest therapeutic efficacy in the cases of SCM was attributed to concurrent treatment with ascorbic acid @ 5 g I.M. x 3 days and cefquinome sulphate @ 75 mg intra-mammary infusion x 3 days viz. 83.33 and 90.90 per cent animalwise and quarterwise, respectively, followed by cefquinome alone 83.33 per cent animalwise and 87.50 per cent quarterwise. Milk malondialdehyde level was found to be increased in sub-clinical mastitic cases suggesting oxidative stress, which was significantly reduced by ascorbic acid @ 5 g intramuscularly for 3 days. Antibiogram of various isolates from bovine intramammary infections, revealed 70-100 per cent Staphylococcal, Streptococcal and Corynebacterial strains sensitive to majority of 14 antimicrobials used, whereas Ps. aeruginosa strains were resistant to all except enrofloxacin, ciprofloxacin and amikacin.