Building grass for autumn is now well underway; however ground conditions are deteriorating after prolonged heavy rainfall in many areas.
Target rotation length is now 30 days.
To calculate what cover/cow we require for a 30 day rotation:
Demand per cow x rotation length target / 2.
E.g. Assuming a daily demand per cow of 18kgs and target round length of 30 days:
18kgs x 30 = 540.
540 / 2 = 270kg cover/cow target.
It is very difficult to build up enough grass in autumn without having an autumn grass budget completed.
This helps us to have a controlled build up, rather than achieving peak AFC too early, resulting in excessive pre grazing covers and suppressed regrowths.
Peak AFC must be realised by balance day; the day when growth rates meet demand. A maximum cover per cow of 450kgs up to a maximum AFC of 1200kgs is the objective.
Any higher covers than this will create difficulty in getting 60% of the milking platform grazed within the first 30 days of closing, beginning in October.
On heavy clay soils that can be very difficult to graze in late autumn, it is likely that building cover/cow up to 450kgs may create too high pre grazing covers if the weather was to break.
Therefore, a lower cover/cow target should be set based on what has worked best over previous years. There is no set target for all, as soil types vary so much between farms.
Cathal McAleer is a grassland consultant working with individual farmers and facilitating discussion groups throughout Ireland.
You can contact Cathal on 087 160 2491 / 0044 7749 531679 or by email:[email protected]