Discipline: mastitis; Key words: teat canal, udder health, milking machine settings, milk flow, VaDia, take-off time, vented liners.

The preservation of the teat canal is crucial for udder health, as the main route for bacterial infection is via the teat canal. Milking machines differ in layout and settings and continue to be a challenge to the primary immune system of the bovine udder namely the teat canal. Different levels of teat end vacuum during machine milking may influence milking performance and teat condition. When there is little or no milk flow the vacuum at the teat end increases to that in the milking machine system. This happens when cows did not have a milk let down reflex at the start of milking or at the end of milking when the machine remains on the teats when milk flow has stopped. Once the teat canal muscles are damaged the risk of bacteria entering the udder is increased. The aim of the study referenced below was to see to what extent variation in teat end vacuum is responsible for teat damage and infections in South African dairy herds. 

Initial work was performed with the VaDia at the Experimental farm of the University of Pretoria (UP) in order to test the protocol. The VaDia is an apparatus capable of measuring vacuum in four channels simultaneously and tabulating results and illustrate them graphically. Cows were selected that was suitable for testing based on their teat size and good liner fit. All cows in milk were evaluated and three cows in every group entering the parlour for normal milking were identified. Three VaDias were used simultaneously to obtain more data and to test the repeatability of each of them. The same VaDia was used for testing the same cows on three consecutive days at the same milking. 

In the preliminary investigation, it was found that even in a milking system where the automated cluster removal settings has a short reactive time (short milk tube and a flow meter lower than the level of the udder) the take-off time overall could be improved. The average time of over-milking of the three cows was 1.25 minutes under more or less ideal conditions. It was decided that initial work should be performed on the liners used by most producers in South Africa namely round liners to make the work more relevant in South Africa. Swing-over milking systems, where most over-milking due to incorrect setting of automated take-off systems are anticipated, use only round and also not vented liners and a higher system vacuum is required with the latter. To do more appropriate work the vented triangular liners used at the UP parlour will be replaced with normal (not vented) round liners. An additional VaDia was purchased to make time use during testing more effective. Readers will be informed of progress. 


I –M Petzer, 2019. An investigation into the take-off time in milking machines in South Africa dairies. Milk SA Research Project PRJ-0211.