• 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.
    • Farm management factors associated with the Bacillus cereus count in bulk tank milk

      O'Connell, Aine; Ruegg, P.L.; Gleeson, David E; Teagasc Walsh Fellowship Programme (Teagasc (Agriculture and Food Development Authority), Ireland, 2013)
      The objective of this study was to determine the on-farm management factors that are associated with the Bacillus cereus count in raw bulk tank milk using a cross sectional study design. Bulk tank milk quality was monitored for B. cereus on 63 dairy farms between July and August 2012. Bulk tank milk samples corresponding with processor milk collection dates were taken over a two week period prior to the farm visit and tested for B. cereus. The four most recent samples taken prior to the on-farm visit were averaged and log transformed to give the outcome variable; mean log10 B. cereus cfu/mL. On-farm data collection included recording observations and providing a questionnaire on basic hygiene, management factors and cow hygiene scoring. All independent variables were analysed individually with the outcome variable using simple linear regression and one-way ANOVA; a multivariable regression model was subsequently developed. Only significant variables were retained in the final model (P < 0.05). The geometric mean B. cereus count for all milk samples was 40 cfu/mL. The start temperature of the cleaning solution wash, dry wiping teats prior to unit application, the feeding of silage and reusing the cleaning solution more than once were all unconditionally associated (P < 0.10) with the B. cereus count in bulk tank milk but did not enter the final multivariable model. B. cereus count was four times greater (201 cfu/mL) when cows had been housed compared to when they were on pasture (50 cfu/mL). The allocation of fresh grass every 12 h (62 cfu/mL) resulted in a decrease in B. cereus count (166cfu/mL every 24 h or greater). The testing of water for bacteriology was associated with an increase in B. cereus count. In conclusion, this study highlights specific management factors associated with the B. cereus count in bulk tank milk.
    • 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.
    • Review of potential sources and control of thermoduric bacteria in bulk-tank milk

      Gleeson, David E; O'Connell, Aine; Jordan, Kieran; Irish Dairy Levy Research Trust (Teagasc (Agriculture and Food Development Authority), Ireland, 2013)
      Bacteria that contaminate milk include thermoduric bacteria that can survive pasteurisation and subsequently grow in the pasteurised milk or contaminate product. Elimination of thermodurics at milking is not feasible. Therefore, knowledge of their source and strategies for their reduction are important. The major sources of thermodurics in milk are contamination of the teat skin from soil and bedding, and subsequent contamination from deposits that can build up on milking equipment surfaces. Hygiene at milking can reduce the number of bacteria contaminating milk. Teat preparation at milking and a recommended plant cleaning procedure are critical to the prevention of the contamination of milk with thermoduric bacteria.