At a recent milking time visit to a particularly high producing herd, we noticed mean claw vacuums during our milking time testing often getting as low as 30 – 32 kPa during peak milk flow, despite the system vacuum being 44.5 kPa.
Countdown Downunder recommends mean claw vacuums between 36 and 42 kPa during peak milk flow, so we were keen to understand better what was happening at this herd.
This was an ideal opportunity to use “Daisy”, our artificial udder, to do some true “wet testing” of the machines.
“Wet testing” is the use of an artificial udder and flow meter to mimic milking conditions using water as the fluid, whilst “milking time testing” is the testing of the machines whilst the cows are actually milking (our normal procedure).
The artificial udder told us that to get claw vacuums this low, these cows had to be achieving milk flow rates approaching 8 litres/min. This is quite high for typical Australian cows, where flow rates often don’t exceed about 5 litres/min.
Now that we have this information, we can better understand and interpret what is happening in this herd, and work with the herd’s milking machine tech to ensure the plant can cope with this herd’s cows that have very high milk flow rates.
During this testing, we were also able to mimic what happens if a small air leak occurs around the mouth of the liner during milking (such as might happen with dry, cracked teat skin - see above).
In this case, the claw vacuums were about 3 kPa lower again than without an air leak, clearly demonstrating just one of the ways that dry skin can influence the milking machine’s performance.