Why it could be an expensive winter for dairy farmers if they don't get to grips with rotation plans
Building autumn covers of grass can be a tricky business.
If you don't build enough cows will end up eating too much expensive meals and silage in the month of October, and if you build up too much then you run the risk of leaving a butt of old grass through the winter which is a waste of good feed and will also impact heavily on next spring's grass quality.
Grass growth generally tapers off at the end of August, typically dropping below 60kgs growth per day, and it tails off further as we head into October, dropping to below 40kgs per day. Therefore the grass we graze in October/November has to be grown in September and this won't happen by accident. Table 1 shows the targets we need to be hitting for the month of August in terms of cover/cow and rotation length.
As you can see, the cover that is feasible to build is determined by the stocking rate on the milking block; however, the rotation length targets remain the same regardless of the stocking rate.
Rotation length needs to increase by two days per week from now on. Most farmers try to determine the rotation length by trying to remember when the cows were last in today's paddock, which gives a good indication.
However, a better approach is to divide the amount of ground the cows are eating on a daily basis into the total ground available. If you have 100ac available for the cows and they are eating 4ac per day, then your rotation length should be 25 days.
At the end of August they need to be eating only 3.3ac per day.
Adding two days per week to the rotation length can happen in two ways: increasing the supply of grass or by reducing the demand.
Some may have after-grass entering the system now which will automatically increase the supply of grass available. All others have to depend on fertiliser. The closing date for spreading chemical fertiliser is five weeks away, on September 15.
Those of you who are stocked at greater than 2.5lu/ha need to blanket-spread the farm twice in this period.
Those of you who are lower stocked should go with one application in the next fortnight as the response to nitrogen will be higher in August than in September.
There are numerous options to reduce demand for grass. The first area to look at is stocking rate. All calves and heifers should be sent to outside blocks now.
In addition, scan all milking cows and determine those that are not in calf. Perhaps there may be a market to sell these while milking? An advert online or in the paper will soon find out. Low yielders, thin cows, lame cows and those with mastitis could be dried off and sent to an outside block of ground.
Feeding extra meal may be necessary for some, but it should be a last resort. High-quality baled silage should be introduced before resorting to meal, but on some very highly stocked farms, it may be necessary. A very basic three-way mix will be adequate in most instances.
Ground conditions are good in most areas at present, with the exception of some heavier soils in the west.
Aim to graze out paddocks as clean as possible now because it may not be as easy to do it the next time round. This approach avoids grass being wasted and sets the farm up for the final autumn grazing and also for the first spring grazing.
For those on heavy soils, build as much grass as possible on your drier fields - the ones you know you will be able to graze in October. Then graze the heavier fields when you get the chance to do so.
Joe Kelleher is a Teagasc advisor based in Newcastlewest, Co Limerick
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