User Guide

Milk Yield from Grazing App

Thank you for choosing to download the Trouw Nutrition GB 'Milk Yield from Grazing' app. Please read the following instructions to help ensure that you get the most out of using the app.

It is important to complete every page of the app as accurately as possible, ensuring that each cell is filled in so that the results can be calculated.

Potential Milk Yield

  • From the drop down menu, select the month for which you would like to calculate the Potential Milk Yield from Grazing (M+ litres), usually the current month. Monthly average grass analysis figures are used in the background to calculate the results.
  • Input the handful weight (g). One handful cut 4-5 cm above the ground is equal to one bite. If possible, take several handfuls and calculate the average. For example, take 10 handfuls from across the whole field, weigh the entire sample on kitchen scales (ensuring the weight of the container is subtracted) and divide the weight by 10 to get the average handful weight.
  • Enter the dry matter of the grass. If you do not have an up-to-date dry matter value, either use the Trouw Nutrition GB Data Sheet 'Forage Dry Matter: Microwave Test' to help measure grass dry matter using a microwave (contact Trouw Nutrition GB for a copy) or input an average monthly figure from the table below. It is important to use the most accurate figures available to ensure that the results are as representative of the on-farm situation as possible. See the table below for the Trouw Nutrition GB 10 year average monthly fresh grass dry matter figures (%):
April May June July Aug Sept Oct
19.5% 18.2% 18.3% 18.4% 17.6% 16.7% 15.8%
  • Select the potential grazing hours from the drop down list. If the figure is not known, estimate it as daylight hours minus 4.
  • Press the 'Get results' button. This will populate the results fields below with Potential Milk From Grazing (M+) and the required grass dry matter intake to achieve this.
  • Once you are happy that the figures are accurate, move to the next page by pressing the 'Achievable Milk Yield' tab at the top of the screen.

Achievable Milk Yield

  • Input the number of cows in milk into the first cell. This figure should be the number of cows in the group that will be grazing the field that has been measured.
  • Enter (in acres) the field/paddock size. If you measure field size in hectares, simply multiply the number of hectares by 2.47 to get acres. For example 6 ha x 2.47= 14.82 acres.
  • Use a rising plate metre, or other suitable method, to estimate the grazing entry cover and enter it into the cell. Be aware that this figure is in kg DM per hectare as this is the most common measurement unit.
  • In the next cell, enter the target grass cover when the cows will be removed from the field.
  • Finally, enter the number of days it is planned to graze the field.
  • Press the 'Get results' button to populate the results section below. This will indicate the availability of grass in the field, and whether the potential milk yield will be achievable.
  • Move on to the 'Feed Guide' page by pressing the tab at the top of the screen.

Feed Guide

  • Enter the target milk yield on a per cow basis. Ensure it is the average figure for the cows in the group that is being grazed in the field used for the calculations in the previous pages.
  • Next, input forage buffer information. The forage buffer is the forage portion of any buffer fed, for example grass silage or a grass and maize silage mix. These numbers do not include any concentrates fed in the mix.
  • Enter the dry matter of the forage buffer fed. If there is no forage buffer used, enter '0' in the cell. Use a recent analysis of the forage or calculate the dry matter using the Trouw Nutrition GB Data Sheet 'Forage Dry Matter: Microwave Test' (Contact Trouw Nutrition GB for further details).
  • Enter the metabolisable energy (ME) content of the forage buffer (again enter '0' if no buffer is fed). Use a recent forage analysis report for the ME of your forage. If a report is unavailable, use an average figure. For reference the Trouw Nutrition GB 2015 average forage ME figures are:
    • Grass silage: 10.8 MJ ME/kg DM
    • Maize silage: 11.5 MJ ME/kg DM
    • Wholecrop silage: 10.2 MJ ME/kg DM
  • Finally, enter the amount of forage buffer fed per cow on a fresh weight basis. Enter '0' if no buffer is fed.Once the figures are completed, press the 'Get results' button to calculate the estimated amount of concentrates that are required to achieve the target milk yield.