Influence of environmental and pulsation factors on teat skin condition and teat tissue with regard to mastitis
Milking and non-milking influences on teat skin and tissue parameters were examined in a series of trials in New Zealand at the Dairying Research Corporation, Hamilton and on farms within a 100 km radius of Hanover, in Germany. In New Zealand, identical twins were available for six short-term trials and one long-term trial, involving 10 twin sets. In Germany, one main trial was carried out, with 253 unrelated cows located on four participating dairy farms.
A method to determine the pH and the moisture of bovine teat skin was developed.
The long-term effects of machine milking on teat skin and tissue parameters were studied. Additionally different teat sanitiser formulations were compared with regard to their teat-conditioning characteristics.
The determination of the teat skin parameters pH and moisture was possible, with the Corneometer CM 820 and Skin-pH-Meter PH 900 (Courage and Khazaka electronic GmbH, Cologne, Germany). The parameter moisture demonstrated substantial variability. The test of repeatability resulted in a coefficient of variation (cv) of 25.6 per cent for moisture and 6.07 per cent for pH. The reproducibility over time resulted in similar cvs for teat skin pH and moisture as in the test of repeatability. Teat skin moisture and pH were not significantly correlated. The teat skin moisture was determined in arbitrary units.
The average teat skin pH of New Zealand cows varied from 6.44 to 6.88 for lactating cows and from 7.06 to 7.26 for dry cows. German lactating cows had a mean teat skin pH of 7.19 to 7.26. In New Zealand, the teat skin moisture of lactating cows fluctuated between 23.9 and 39.8, and between 23.0 to 57.5 for dry cows. The average teat skin moisture of German lactating cows ranged from 46.6 to 47.8.
The teat skin parameters and measurements were subject to environmental influences. The teat skin moisture was correlated with the environmental temperature on a low level. The teat skin pH correlated with the environmental temperature and the relative humidity.
An am/pm effect of moisture was also observed. The environmental temperature and the teat skin moisture were significantly higher in the afternoons than in the mornings.
The milking interval did not have any influence on teat skin moisture or pH. The application of a post milking teat sanitiser, containing iodine and a mixture of glycerine and sorbitol, increased the moisture of teat skin significantly. This increase was observable up to 16 h, but after 24 h, the effect had deteriorated. The low pH of the sanitiser solution (3.3) had a very strong, decreasing influence on the teat skin pH. PH values as low as 4.46 were determined and the effect was still detectable after 16 h.
In a half udder design with crossover involving six identical twin sets, six different teat sanitiser formulations were tested regarding their teat conditioning properties. The positive control contained the highest level of emollient (glycerine and sorbitol) and resulted in higher moisture readings than most other teat sanitisers. Yet, this effect deteriorated over time and was not observable after 24 h. The level of glycerine in the sanitiser influenced the moisture level on the skin. The sanitiser containing sorbitol alone did not result in moisture values as high as mixtures including glycerine. Products without emollient did not moisturise the teat skin as well as products with emollient.
The acidity of the sanitiser caused a decrease in teat skin pH. Products with a pH around neutral did not change the teat skin pH whilst treatments with the same pH (3.5) resulted in approximately the same pH occurring on the teat skin. In this experiment, it was not possible to test the products without emollients.
The influence of the treatments on the teat skin flora was tested, taking rinsing samples at the end of each five-day treatment period. The teat skin flora observed on untreated skin was similar to the microflora reported in the literature. However, no effect of the sanitiser treatment on the number of teats colonised with a particular group or genus of bacteria could be found. No pattern could be discerned for the distribution of type of bacteria over treatments or different teats.
Ten twin sets were used to compare two different pulsation modes in a long-term trial, with split twin set design. The group, treated with the ‘fast’ milking mode, with a dynamic [b] phase exhibited significantly higher teat thickness changes than the group treated with ‘slow’ pulsation mode. The teat end thickness change decreased throughout the lactation for both treatment groups. The milk yield was significantly correlated with the teat end thickness change for the treatment group milked with the
‘fast’ mode.
The pulsation treatment had no significant effect on teat skin moisture or pH. Quarter foremilk samples were analysed for bacteriology but no significant influence of quarter health on teat skin moisture, pH or thickness change was observed.
In the final trial, the udder health of 253 German cows was compared with teat skin moisture and pH. No significant correlation of these parameters was observed.
Analysis of the data indicated that time, farm and individual cow factors influenced the teat skin parameters to a greater extent than the udder health on quarter basis.
Using the corneometer and pH-meter to determine bovine teat skin moisture and pH proved to be a simple and non-invasive technique, appropriate for use with dairy cattle. Environmental factors influenced skin moisture and pH to a high degree and future studies will need to keep as many of these factors (temperature, humidity, bedding etc.) as stable and controlled as possible during the experimental phase.