Wet weather management is the order of the day from now on, or at least for as long as the weather keeps playing up.
This means using 12 hour breaks, back-fencing and on/off grazing if necessary. To accurately allocate grass, you need to know the how much grass the cows need to eat and how much area to give them.
There are a few ways of doing this. The following are two example approaches;
1 Work out how many cows are going to be grazing and how much grass they are going to eat per grazing. For example, 100 cows eating 8kg of grass per grazing means the total amount of grass being allocated is 800kg of dry matter per grazing.
2 Work out the area of the paddocks and the amount of grass in it. For example, a 2.4ha paddock with a cover of 1,400kg/ha means the total amount of feed in the paddock is 3,360kg.
3 Divide the daily allocation by the total amount of feed in the field to work out how many grazings are in the paddock. In this example, there are 4.2 grazings in the paddock.
The following method is more suitable when cow numbers are changing regularly or where grass covers differ across the field.
1 Work out how many cows are grazing and how much grass they are eating in the 12 hour break, for example 100 cows eating 8kg is a total demand of 800kg.
2 Work out how many square metres are needed to give 1kg of grass dry matter. To do this, divide the cover into 10,000. For example, a cover of 1,400kg into 10,000 is 7.14m2 per kilo of dry matter. The higher the cover of grass, the lower the number of metres to get 1kg of dry matter.
3 Multiply this number by the demand to work out the total allocation. So in this case, 7.14 multiplied by 800kg is 5,712m2. This is how much area you need to give the cows.
4 To work out where to put the fence, measure the width of the paddock and then divide this into 5,712. For example, if the paddock is 120m wide, the strip wire should be placed 48m back.