• Are some teat disinfectant formulations more effective against specific bacteria isolated on teat skin than others?

      Fitzpatrick, Sarah R; Garvey, Mary; Flynn, Jim; Jordan, Kieran; Gleeson, David E; Dairy Research Ireland; Teagasc Walsh Fellowship Programme; 2016054 (Biomed Central, 2019-04-25)
      The use of pre- and post-milking teat disinfectants can reduce teat bacterial load and aid in the collection of high-quality milk. The objective of this study was to compare the reduction in bacteria populations on teat skin after the application of different commercial teat disinfectant products. Ten teat disinfectant products were applied to the teats of 10 Holstein–Friesian cows. One cow received one teat disinfectant product at each sampling point before cluster application for milking. A composite swab sample was taken of the 4 teats of each cow before and after teat disinfectant application. Swab samples were placed on three different selective agars to enumerate bacterial counts of staphylococcal, streptococcal and coliforms isolates on teat skin. Staphylococcal isolates were the most prominent bacterial group recovered on teat swabs (49%), followed by streptococcal (36%) and coliform (15%) isolates before the application of disinfectant. The average bacterial reductions on teat skin were shown to be 76%, 73% and 60% for staphylococcal, streptococcal and coliform isolates, respectively. All of the teat disinfectant products tested reduced teat bacterial load for all three bacterial groups. Product 4 containing 0.6% w/w diamine was the most effective against bacterial populations of staphylococcal and streptococcal isolates on teat skin with a reduction of 90% and 94%, respectively. Whereas product 10, which contained 0.5% w/w iodine, resulted in the highest reduction in coliforms on teat skin with a reduction of 91%. Results from this study suggest that specific bacterial population loads on teats can be reduced using different teat disinfectant formulations.
    • 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.
    • Iodine concentrations in milk

      O'Brien, Bernadette; Gleeson, David E; Jordan, Kieran; Irish Dairy Levy Research Trust (Teagasc (Agriculture and Food Development Authority), Ireland, 2013)
      Iodine tends to be supplemented at farm level in the expectation of increasing cow health and fertility. There is concern that such practices may result in high milk iodine, which could affect ingredients for infant formula and, thus, dairy export markets. The objective of this study was to quantify the effect of iodine fortified feed and teat disinfection practices of dairy cows on milk iodine concentration. Thirty lactating cows were fed 7 kg, 3 kg (10 mg iodine/kg) and 0 kg of concentrate feed during 3 periods of 35 days each. During the first 14 days of each period, cows were on dietary iodine treatments only; during days 15–21, one of three teat disinfection treatments (n = 10) was applied (in addition to the dietary iodine treatments): non-iodine (chlorhexidine) post-milking spray; 0.5% iodine spray post-milking; 0.5% iodine spray pre- and post-milking. Cow milk yield was 21.3 kg/day. Individual cow milk samples were analysed for iodine concentration on 2 days at the end of each treatment period. Dietary supplementation of iodine at both 30 mg and 70 mg/day, when compared to the diet with no supplement, increased milk iodine concentrations significantly (P < 0.001) from 449 to 1034 and 915 μg/kg, respectively. Teat disinfection both pre- and post-milking increased milk iodine concentration at each of the dietary supplementation levels of 0, 30 and 70 mg/day compared with a non-iodine teat disinfectant (P < 0.001). In conclusion, both dietary iodine supplementation and teat disinfection iodine increased milk iodine concentrations in an additive manner, exceeding common target values of 250 μg/kg. As both iodine treatments can occur simultaneously on farm, supplementation strategies should be monitored.