• Effect of pre-milking teat disinfection on new mastitis infection rates of dairy cows

      Gleeson, David E; Flynn, James; O'Brien, Bernadette (Biomed Central, 2018-04-18)
      Background The practise of teat disinfection prior to cluster attachment for milking is being adopted by farmers in Ireland, particularly where there are herd issues with new infection rates. Pre-milking teat disinfection has been shown to reduce bacterial numbers on teat skin and to be most effective against environmental bacteria such as Escherichia coli and Streptococcus uberis. A split udder design experiment was undertaken on two research herds (A = 96 cows: B = 168 cows) to test the benefit of pre-milking teat disinfection on new mastitis infection levels. The disinfectant was applied to the left front and right hind teats of all cows in each herd and the right front and left hind teats received no disinfectant treatment prior to milking over a complete lactation. Individual quarter foremilk samples were taken on 5 occasions during the lactation and all clinical cases were recorded. The presence and number of staphylococcus and streptococcus bacteria on teat skin of a random sample of experimental cows (n = 20) was measured on 3 occasions during lactation (April, June, and October). Results Pre-milking teat disinfection had no significant impact on quarter SCC and new infection rates (P > 0.05). The median SCC was 169 (95% CI = 144–198) × 103 cells/mL and 170 (95% CI = 145–199) × 103 cells/mL for disinfected teats and non-disinfected teats, respectively. There were no differences in SCC observed between herds (A = 161 (95% CI = 127–205) × 103 cells/mL; B = 169 (95% CI = 144–198) × 103 cells/mL) over the complete lactation. Bacterial levels on teat skin were reduced significantly with pre-milking teat disinfection compared to teats receiving no disinfectant (P < 0.001). Total infections (clinical and sub-clinical) were similar for disinfected teats (n = 36) and not disinfected teats (n = 40), respectively. Staphylococcus aureus (n = 47) and Strep. uberis (n = 9) were identified as the predominant bacteria in quarter foremilk samples with both clinical and sub-clinical infections. Conclusion SCC and new infection rates were similar in non-disinfected teats and disinfected (pre-milking) teats. The routine application of pre-milking teat disinfectant in pasture-grazed herds is unlikely to be of benefit where herd SCC is below 200 × 103 cells/mL.
    • Evaluation of hydrated lime as a cubicle bedding material on the microbial count on teat skin and new intramammary infection

      Gleeson, David E (Teagasc (Agriculture and Food Development Authority), Ireland, 2013)
      In two experiments, the effect of applying hydrated lime as a cubicle bedding material on the microbial count on teat skin and new intramammary infection were evaluated. In experiment 1, dry dairy cows (n=60) were assigned to one of three cubicle bedding treatments for a 5 week period. The treatments applied were: Hydrated lime (HL), HL (50%) + Ground limestone (50%) (HL/GL) and GL. In experiment 2, two teat disinfectants products chlorhexidine (CH) and iodine (I) were applied to teats at milking in conjunction with two cubicle bedding materials with lactating cows (n=60) for a sixweek period. The treatments applied were: HLCH; HLI; and GLI. The HL treatment had significantly more teats (P<0.001) with no Staphylococcus spp. or Streptococcus spp. bacteria present compared to GL. There were no differences observed between treatments for California Mastitis Test (CMT) score at calving or somatic cell count (SCC) post-calving. In experiment two, the HLI treatment tended (P<0.08) to have lower bulk milk SCC than the GLI. The average bulk milk SCC over the trial period was 68,000, 54,000 and 83,000 cells/mL for HLI, HLCH and GLI, respectively. The incidences of medium-term teat changes were numerically higher with HLI and there were no differences in the mean hyperkeratosis score between treatments. The mean teat hyperkeratosis scores on day 42 were 2.2, 2.1 and 2.1 for HLI, HLCH and GLI, respectively. The HLI treatment had lower levels of Staphylococcal and Streptococcal bacteria on teats compared to GLI (P<0.001). Hydrated lime could be successfully used as cubicle bedding material for dairy cows if used at the recommended rates with either chlorhexidine or iodine based teat disinfectants.