Automatic milking

An automatic milking system contains several cleaning cycles, each with their own goals: Complete cleaning and disinfecting. This is a cleaning cycle in which the complete milking installation is cleaned and disinfected. Short cleaning cycle. Is carried out after the milking of a cow whose milk is rejected because of mastitis or antibiotics, in order to flush milk residuals. It is also carried out when a number of cows have been milked, in order to clean a part of the installation. Teat cup cleaning. Is carried out after each milking, in order to flush milk residuals and micro-organisms, especially mastitis pathogens. The effectiveness of the different cleaning cycles is determined by the amount of water, the temperature and chemicals used in combination with the frequency of the cleaning.

• Subpackage 1: to determine the demands for the cleaning procedures by automatic milking systems.
• Subpackage 2: to establish and optimise the effectiveness of the three different cleaning cycles of an automatic milking system in order to ensure a good milk quality under optimal use of time, energy, water and chemicals.
• Subpackage 3: to determine the effectiveness of teat cup cleaning in order to prevent transport of mastitis pathogens from cow to cow.

The work package will be carried out in three phases. The first phase will start with a desk study in order to determine the demands for cleaning of equipment on a farm with an automatic milking system. Knowledge and literature will be used to produce a document that can be used as basis for the remaining part of the work package. A workshop will be organised with the three partners for assessment of the demands. The document will contain the state of the art of cleaning systems available on the automatic milking systems that are marketed. This first phase is a co-production of partners 1, 2 and 7.

The second phase consists of screening test and optimisation tests. It will start with a screening test in which the importance of effectiveness determinants is examined. The screening test will be a factorial experiment with a number of factors being varied at two levels according to the following scheme: complete cleaning and disinfecting: frequency every 6 and 12 hours; short cleaning cycle: frequency no (except antibiotic milk) or normal, temperature cold or warm; teat cup cleaning: frequency after one or two milkings, temperature cold or warm, with and without chemicals. The microbiology (Total Plate Count (TPC), lactobacilli and thermodurics) of the milk produced during the last two hours before the next complete cleaning and disinfecting is started, is determined. The bacterial load of the teat cups is determined by taking rinse samples with sterile milk from 2 teat cups of a milk cluster, just before the next complete cleaning and disinfecting. This experiment will be done with one automatic milking system. The results will be evaluated for effect on bacterial count in the milk and teat cup, use of water, energy and chemicals and time demand.

Based on the results of the screening test, optimisation of the cleaning methods will take place in a second factorial experiment. This will take place for three different automatic milking systems on one farm each. The four most important variables are tested for longer time. Variables are changed every 3 weeks. Every milk delivery, TPC, lactobacilli and thermodurics will be monitored. At the end of every 3 week-period, bacterial counts of milk and teat cups are determined. Also critical points in the automatic milking system will be monitored using visual inspection and ATP measurements. The complete test is repeated 4 times. Finally, water, energy and detergent usage and time demand will be monitored. Partner 1 and 7 will do the experiments.

In the third phase the effectiveness of teat cup cleaning in preventing transport of mastitis pathogens from cow to cow is investigated. Based on the results of the screening test for bacterial count in the teat cup, laboratory tests are performed to determine the effect of the two most effective teat cup cleanings on the reduction of mastitis pathogens. References are no teat cup cleaning and teat cup cleaning with cold water (common practice). Properly cleaned and disinfected teat cups will be artificially contaminated with 2 different mastitis pathogens. After contamination teat cup cleaning is performed according to the test scheme. The bacterial load of the teat cups is determined by taking rinse samples with sterile milk. TPC and the number of mastitis pathogens are determined. The test scheme is repeated 4 times. Results are evaluated for effectiveness of mastitis pathogen removal. To determine the effectiveness of teat cup cleaning in preventing transport of mastitis pathogens from cow to cow, a split-udder experiment will be performed. In one udder half the most effective teat cup cleaning is performed, in the other half no teat cup cleaning is performed. Cows will be balanced between the groups by parity, stage of lactation and bacterial status. The cows in each herd will be maintained under the same conditions of management. Experimental units needed are 628 per treatment (in total 314 cows), approximately 6 farms with one automatic milking unit. During one year quarter incidence of mastitis will be recorded, under the assumption that all the mastitis cases will be detected properly.

• D16: Report describing the various methods used to clean equipment of an automatic milking system.
• D17: Report describing optimised cleaning systems, with implications for milk quality, water, energy and detergent use and time demand.
• D18: Report describing effectiveness of optimised teat cup cleaning in the prevention of mastitis pathogens transfer from cow to cow.

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