I have to admit getting this grassland management thing right is quiet hard work. I had a few days off last weekend and spent the whole time worrying about how far the electric fence was being moved each day and which field the cows were in.
Just yesterday I made a really important decision and that was to mow the grass for 1st cut silage. Not only is this really important in terms of timing to ensure we harvest the best quality material for next winter but, also, it means our grazing block is now fixed for the next few weeks – I can no longer choose to let the cows stray into some silage grounds if I feel grass is getting tight.
It does seem like grass growth has slowed up in the last week and there is talk of a few cold days to come at the end of this week. But, what is interesting is that a couple of old pastures that have never been reseeded in my 13 year tenure are growing better than anything else right now. Both have produced average growth rates in excess of 120kg of dry matter per hectare over the last five days, whilst newer leys have dropped back to around 70kg. Perhaps this is down to the type of grass in these older pastures, which are hitting their seasonal peak now. One of the fields in question was used at the recent BGS Reseeding Day to illustrate pasture that is in need of some improvement. A month ago it did look less productive than anything else on the farm but now it is competing well. It will be interesting to see what it has delivered at the end of the grazing season.
Right now we are grazing 180 milking cows on a block of 44 hectares of grass, made up of nine fields. The rotation of cows around the block has been steady at about 18 days for the last couple of weeks. But, I am a bit worried that if grass growth drops later this week we could see cows completing the rotation in 15 days or less. I applied a bit more fertiliser to recently grazed fields yesterday in an attempt to keep grass growth up. I have calculated a simple ‘grass balance’ to look at supply and demand for our cows over the next week, as shown below:
|Number of cows in milk||180|
|Grazing demand / cow / day||17kg Dry Matter|
|Total daily grazing required||3,060kg Dry Matter|
|Grazing area (hectares)||44|
|Current average growth / ha / day||75kg Dry Matter|
|Total daily grass supplied||3,300kg Dry Matter|
|Supply / Demand balance||240kg Dry Matter|
This simple calculation gives me some confidence that we can keep enough grass in front of the cows for now. If average daily growth rates fall below 70kg DM a day then things will get tight. However, by the time we see a seasonal slow down in grass we should have the option to take some of the grounds now cut for silage back into the grazing block and stock the cows less tightly.
As relatively green student of the green stuff, I can only share my experience and learning here. But, I urge any dairy farmer who is not regularly walking their pasture and recording how many days the cows spend grazing in each field, to start now. Armed with some real data (no matter how simple) we will be on a much better footing to utilise the grass that grows for the remainder of this year and into 2014. The easy option is often to say “grass isn’t worth much so we need to feed more purchased feed to keep milk up”. Don’t be put off by salesmen prophesising a meltdown in your herd if you don’t feed this that and the other. Aim to buy as little in as possible and instead invest your time and energy in making more of what you have on the farm.
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