Cleaning and stimulation of teats in an Automated Milking Rotary

Abstract In automatic milking systems (AMS) teat cleaning and stimulation of milk let-down are performed automatically in a standardized process before milking. The settings for teat cleaning must meet the requirements for hygienic quality of the milk delivered to the dairy plants. Moreover, the stimulation of milk let down must meet the requirements for high milking efficiency at farm level. The latest addition from DeLaval is the automatic milking rotary (DeLaval AMRTM) which has the capacity to work with five robots on five cows at the same time. The AMR has different time settings for teat wash and time out time (TT), the time allowed for each wash station to finish the preparation of two teats. Depending on time settings that are used, milk hygiene and milking efficiency can be affected. The short term aim of the project was to optimize cleaning and stimulation of the teats before milking, and the long term aim was to improve milking hygiene to maximize milking efficiency and milk quality. The project was carried out at the Swedish Livestock Research Centre at Lovsta, Swedish University of Agricultural Science in Uppsala. It was divided into two studies of which the first investigated how different teat wash times (WT) (3.5 s, 5.5 s and 7.5 s) affected teat cleanliness and milking parameters as incomplete milking, attachment failure, kick-off, milk yield, milking time and milk flow in the DeLaval AMRTM. The second study investigated how different TT (25 s and 30 s) using a WT of 5.5 and 7.5 s affected teat cleanliness and milking parameters using the same outcomes as in the first study. In both studies, all cows included were subjected to all treatments in a crossover design. In the first study, it was found that the probability of high hygiene scores, i.e. dirty teats, was significantly lower afterWT 5.5 s and 7.5 s compared to afterWT 3.5 s. The probability of high hygiene scores was also significantly lower after WT 7.5 s than after WT 5.5 s. Results also showed that WT had significant effect on milking parameters. The risk of incomplete milking and attachment failure was higher after WT 3.5 s compared to WT 5.5 s and 7.5 s. A lower milk flow was found after 3.5 s WT compared to 5.5 s and 7.5 s WT. Significant differences in incomplete milking, attachment failure and milk flow were not found between WT 5.5 s and 7.5 s. In the second study, significant differences in hygiene assessments, incomplete milkings or attachment failures were not found between the two TT tested. A TT of 25 s, resulted in more kick-offs compared to TT 30 s when the WT was 5.5 s. However, the same results were not found when using a WT of 7.5 s. It was concluded that a WT of 7.5 s resulted in best teat hygiene score. It was also concluded that the teat WT before milking cannot be shortened from default 5.5 s to 3.5 s (default TT 30 s) without risk for deterioration of the teat hygiene and milking parameters studied. Moreover, when using WT 5.5 s the TT can probably be shortened from 30 s to 25 s without deterioration of the teat hygiene and milking parameters studied. However, further assessment of the effect on teat hygiene is needed since teat hygiene was only evaluated on the right side of the udder.