Assessing Adrenocortical Activity in Dairy Cows During Simulated Power Cuts in Milking Robots

The effects of unsteady electricity supply (power cuts) to an automatic milking system (AMS) on cattle behaviour caused by load management, are crucial for the success of the future farming technologies summarized by ―Integrated Dairy Farming –Stable 4.0‖. The influence of simulated power cuts on adrenocortical activity was assessed by a non-invasive stress monitoring method determining faecal cortisol metabolites (FCM). This study was carried out on four commercial dairy farms in Bavaria, Germany, from March to August 2014. All farms were using 1 Lely AMS for about 60 dairy cows. 12 adult Fleckvieh, aged from 2 to 8 years (average 3.9) were randomly selected per farm. They had between 1 and 7 lactations (average 2.4). The cows under observation were given 6 days to get used to a daily routine. On days 7 to 9 baseline faecal samples were taken. On days 10 to 13 a power cut was simulated daily. Samples were collected manually from the rectum approximately 10 to 12 hours after the simulated power cut and another one approximately one hour later. The amounts of FCM were determined via an 11-oxoaetiocholanolone enzyme immunoassay, measuring 11,17dioxoandrostanes. All data were initially collected with the program Excel 2010 and evaluated with R version 3.0.1. Per farm, no differences between baseline and test days were detected (Kruskal-Wallis, all p-values > 0.1), thus FCM values indicated that cows were not stressed. There was no significant correlation between measured FCM values and the difference between expected and actual milk yield, with the exception of one farm, where actual milk yield was lower than predicted.It was not possible to show that a short malfunction of AMS causes stress in dairy cows. Nevertheless, new questions arose which can be elaborated in additional studies.