Grazing- A month late and the chickens are coming home to roost!

Published 5 June 15

As I drive around the country I see a lot of grazing that has got away from the herd, says AHDB Dairy Technical Extension Officer, Piers Badnell. This leads to a huge amount of waste and lost potential. Invariably, this is due to cows going out a month too late and into covers that are too high. In these conditions, the cow is never going to hit a good residual, as she has far too much choice of food and so she will browse instead of graze efficiently. This leaves patches which, by the next grazing round, are going to be stemmy, unpalatable, lower quality and will thus be rejected again. 


Cows grazing grass with obvious signs of selection, showing rejection patches.

The ultimate conclusion to this scenario is low quality and quantity, and by September 60-70% of the field will be rejected. Part of this downward spiral is that as quality and palatability reduces, buffer feeding commences to take account of lower quality and poor grazing by the cow. This then accelerates the problem as it teaches her that she does not have to graze. Her dung becomes large and fibrous, taking a long time to break down and increasing rejection areas and compounding the problem even further.

If you are faced with this scenario, now is the time to rescue the situation. It can be done but it will take intervention.

In early March I visited a farm where the grass quality was excellent as, in the autumn, the swards had been grazed hard and cleared out. As you would expect, the covers were not large but a number of the fields were at the 2.5 to 3 leaves stage and measured 2,200-2,400kg DM/ha. This is exactly where you want to be at this time of year.

The herd is calved all year round and sells 8,500 litres/cow per year. There were about 90 cows below 30 litres and in calf, so ideal for grazing. My suggestion to turn these cows out to these swards, was rejected because of perceived complications and drops in yield and so the cows did not go out.

If the cows had gone out, they could have gone round the grazing block by my next visit in early April and had between 5-8kg DM/day/head, which would have been maintenance (M) to M plus five litres. It would also have set the grazing up and kept it under control. Grazing would need to be kept tight to drive for residuals.

At my next visit in mid-April, cows had just gone out into swards with covers well over, 3,000kg DM/ha and were apparently milking well. However, the residual was 2,200kg DM/ha, the cows were browsing, they had left large areas and were wasting far more than they were utilising.

That herd should certainly be grazing at minimum 14kg DM/day at 12 ME (M+16) and on good dry days with plenty of time at grazing and not too far to walk, 16-17kg DM potential intake would be possible (M+ 21 -23 litres). Even with a bit of concentrate supplementation for some in the group, this would be efficient and economic milk production and would drive grass quality for the rest of the season.

Graph 1 below, shows the amassed and averaged data from the Forage for Knowledge farms. It shows on the six year average line (orange 2009-2014) that growth on 1 March is about 10kg DM/ha, with 2015 about half this. As such, at this time of year, covers are lower and growth seems to the eye as zero and therefore, it is too early to turn cows out.

Roll a month further on and growth on the six-year average is about 30kg DM/ha per day. Another month later on and the average reaches 55kg DM/ha per day (many people in the last month have reported growth rates of 80-100kg DM/ha per day). Growth accelerates very quickly with extending day light and warmth, far faster than the animals can keep up.

Graph 1 Forage for Knowledge season grass growth

FfK graph

To further illustrate the dilemma, in the earlier discussed herd, there were 90 cows suitable for grazing from 1 March and at a stocking rate for the season of three cows per hectare on the grazing block (certainly not highly stocked). The area required is 30ha. On 1 March the average farm cover is 2,100kg DM/ha, which is an appropriate figure for the season once growth comes and an appropriate figure to start the season on.

Between 1 March and 1 April the average growth for that month is approximately 15kg DM/day for those 31 days that equates to 465kg DM growth), added to that average cover of 2,100 = 2,565kg DM/ha. From 1 April to 15 April the average growth is 35kg DM/ha/day = 525kg DM. Again add to this the average farm cover it gives 3,090kg DM/ha. So if 3,090kg DM is the average farm cover, there will be some paddocks at 3,500kg (as well as some below) and for most cows it is difficult to take residuals down to 1,500kg DM/ha. Beyond 3,000kG DM/ha, grass quality is declining.

So, from the example of the cows going out in mid-April, growth at this is at 40kg DM/ha/day and there are 30ha so growth is 1,200kg DM per day on the grazing block as a total. Divide this by 90 cows and this is just over 13kg DM each cow has to eat per day, just to stand still. And this is without taking into account that the average cover is at 3,090kg DM/Ha. Therefore, these cows are not going to get this grazing under control on their own. Thus, covers rise, cows select and waste accumulates!

In order not to have this problem next year, I recommend you make a note in the diary for next February, to walk the farm and plan the early March turnout, whether you are autumn block or all year round calving. Spring calvers are out from the start of calving but on day one there are only a few calved so demand is low. Demand builds as grass growth does and can be managed that way.

It is not too late to do something about grass that has got away from you but it is going to take some work to get it back. As all the country has had rain recently, soil moisture will be pretty good. We are at the beginning of June so, combined with long days and warmth (see the long range forecast on the BBC), this means good growing conditions – you will need to be aggressive.

My advice for any paddocks with a lot of waste in the next round, is to silage and turn it into bales to recreate a good residual and a second bite at the cherry. Maintain grazing pressure to get consistent clean-out and to hit residuals.

Another suggestion is to pre-mow, wilt and graze. One member of a discussion group had got into a situation whereby the average cover was too high a month ago. As he was not keen on baling, because stocks were good and he did not want the expense, he decided to pre-mow, wilt and graze. According to him the cows were able to eat more and as such, they ate their way out of the surplus. Another option would be to use young stock (second season) or dry stock. The key message here is to reinstate the residual and then put pressure on it.

On the AHDB Dairy YouTube channel you can watch a short film with Bill Batten, who pre-mows and grazes all year, in which he explains the advantages for him.

Swards are heading and as a result they naturally become a little stalkier. Once headed, grass quality drops. A way of avoiding this is to graze a sward at two leaves when the head is still in the plant and at this stage is far more digestible. As a perennial, ryegrass plants only head once; if you graze it before it appears, it won’t head again.

Having said that, most plants will have headed and after three to four rounds some fields may need a refresh as a result of a bit of rejection, heading, etc. This can be done by baling it next round or pre-mowing, wilting and grazing. The following photos show this in operation and the result and aftermath with good potential regrowth.

Swards to be pre mown

Image 3

Image 4

Cows nearly finished

Image 5

Sward regrowing 

Image 6

With regards to pre-mowing, it is not really suitable for covers over 3,000-3,500kg DM/ha and if doing for a first time, the cows will need an edge of appetite. Try it in dry weather and don’t give cows too big an area, as they will not physically be able to eat it and thus leave some. As a guide, if a paddock is normally three feeds, pre-mown it is more like four feeds, as they are meant to eat it all. If the cows have not done it before, pick a good day and persevere with it. Once trained they will actually eat more and can, as the example above shows, eat their way out of a surplus if it isn’t huge.


  • Measure – plate meter
  • Out a month earlier if not already doing it
  • Reinstate the residual if needed
  • This time of year no more than a few days grass in front of you
  • Set up your grazing in the autumn
  • Walk it in January.