The calculator can be used in two ways:
You can enter your current details and the calculator will predict a herd milking time. If this number is significantly less than your current milking time, it highlights that improvements can be made to your milking routine, for example by improving cow flow.
Alternatively you can use the calculator to estimate the size of the improvements to milking efficiency you can make by changing your milking strategy (e.g. introducing MaxT).
How do I use the calculator?
- Download and open the spreadsheet.
Note: Ensure 'Rotary' is selected in the bottom left hand corner.
- Enter your farm details in the dark grey boxes (herd size, shed size etc).
Note: you may need to click “enable editing” in the yellow ribbon across the top of the window.
- All the dark grey boxes in the left hand column must be filled in.
Note: roll the mouse over the cell (red triangle) for a more detailed explanation of each box.
- Select the post-milking strategy you use at each milking and the average rotation time.
- The light grey boxes in the middle and right hand columns are a prediction of key measures for the morning and afternoon milkings; particularly focus on the cows/operator/hr which determines the total labour hours.
- Download and open the spreadsheet.
Understanding the results
- Do a quick logic check of the results – are there any impossible results e.g. a herd milking duration of 10 hours. If there are problems, check back to the input boxes. Note that the number of operators is predicted by the model and cannot be entered.
- To calculate the number of operators, the model first estimates a cow milking time based on the milk yield for each milking as determined by what has been entered in box c) and d). It then estimates the number of cows that would require a second rotation by comparing the milking time and the rotation time entered (h). Using the rotation time the number of go-around cows and the number of bails (b) it calculates the time available per cow to attach clusters. If the time available is less than entered in (e) then the calculator assumes a second cupper is added. Similarly if manual cluster removal is selected an additional operator is added.
- The model determines a maximum potential given the values that have been entered, so it is likely that your actual performance will be slightly lower e.g. due to empty bails. If the actual performance is well below what the model has predicted then it is possible that poor cow flow may be reducing efficiency. See the design pages or Milk Smart workbook for rotaries to help diagnose problems.
- Next, explore different end-of-milking strategy (and rotation times) to determine if your milking efficiency can be improved further. The graphs at the bottom of the page give you an indication of the range in potential performance for a number of situations. Pay particular attention to the yellow box, total labour hours. This is a combination of the estimated time to milk the herd, and the number of operators required.
Suggested things to try
In the rotary, start with the end-of-milking criteria.
If using ACR milk flow rate thresholds, then select a rotation time where about 15-20% of cows are going-around. However, then check the number of operators required. If reducing the rotation time has meant an additional cupper is required then consider whether cupping technique can be improved (reduce box e), or increase the rotation time slightly – as it is unlikely the increase in throughput will justify adding another cupper.
If selecting MaxT as an end-of-milking criteria then select a rotation time where 20% of cows will have their milkings shortened e.g. not allowed to go-around on a second rotation. The number will turn red if greater than 20%. As with the previous example, it may make sense to shorten the milking duration to less than 20% of the cows if it avoids needing another operator.
Compare the number of total labour hours in your new scenario compared to what you started with. Refer to the pages on MaxT and go-around cows for more information.
Finally, try out the new scenario at home. The great thing about these changes is that you can get immediate feedback on its success.
The MaxT milking strategy can increase the number of cows milked an hour in many dairies without changing the shed, affecting udder health or milk production and quality. Find out more here.
Making sure cows are comfortable while entering and exiting the dairy as well as during milking, will have big benefits for cow flow and efficiency.
Letting cows 'go around' can improve efficiency in a rotary as it can mean less time is wasted. Shortening the rotation time often means less cups idle time. Find out more here.