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Target Grazing Covers on Beef Farms


What are your targets when it comes to good grassland management for suckler cows, weanlings and beef cattle? Is it that they have enough grass in front of them so that they do not run tight on grass? This is not enough explains Pearse Kelly, Head Drystock Knowledge Transfer

Focusing on quantity only is not enough especially from now until the end of the grazing year.  Quantity is important but the quality of grass they are eating is just as critical and may be even more important.  By quality we mean a continuous supply of leafy cover that is high in digestibility.

Very few farms weigh their cattle and so have no idea how much gain they are putting on each day.  From our on-farm weighing Teagasc has regularly recorded very disappointing daily gains on beef farms from July onwards.  More often than not the cattle on these farms never went hungry as they had enough grass at all times, it's just it was often the wrong type of grass they were eating.

How High is Too High?

The first thing that must be got right is the height of grass that cattle are expected to graze out.  This is called the Pre-Grazing Cover.  If this is wrong everything else will quickly go wrong.  Low covers are not a problem when it comes to influencing grass quality (supply will be more the problem with low covers).  High covers are the problem.  If your pre-grazing cover is too high:-

  • There is significantly increased stem in the diet
  • This leads to poor utilisation compared to leafy material being grazed
  • As a result there is a build-up of dead material in the base of the sward
  • This impacts badly on subsequent grass quality
  • Growth rates are less due to less green material
  • Ultimately animal performance is affected

So what then is too high?  The answer is that this depends on stocking rates and the time of year involved.  Lowly stocked farms do not have a big requirement for huge amounts of grass and are also slower to graze through fields/paddocks compared to very heavily stocked farms.  The lower the stocking rate the lower the grass covers cattle/cows should be going into.  In the later part of the year the rotation is longer and so the target covers are also higher.  As the year moves on grass reverts from heading out back to the vegetative stage again and so heavy covers can be built up without affecting grass quality.

The general rule of thumb is that we should be aiming to go into covers that are somewhere between 1,300 to 1,500 kg dry matter (DM) per hectare.  For farmers who are using a plate meter this would equate to a height of 9 – 10 cm of compressed grass.  Lower stocked farms would aim for the lower amount per hectare whereas heavier stocked farms should aim for no more than 1,500 kg DM per ha.

The most striking thing that most will pick up from these figures is the lower than expected target covers to be going into, even on the heavily stocked farms.  Many beef farmers are more used to grazing covers that are over 2,000 kg which is around 12 cm of compressed grass height.  This is the big change a lot are going to have to make if grass quality is to be kept up.

Rotate! Rotate! Rotate!

Of course, if you are not operating a rotational grazing system with at least six grazing divisions per group of stock this will be next to near impossible to achieve.  If cattle are grazing around two to three fields you cannot be going into such low covers as you will very quickly run out of grass.  If you had six paddocks/fields for a group of stock the covers would be slowly dropping from one to the next all the way back to the last one grazed and might look something like this:- 

 

 PKelly

Dealing with Heavy Covers

It is all very well having a target cover for going into but what can be done if your next field/paddock has significantly heavier covers than it should have?  The first question that then needs to be answered is how much grass do I have on the rest of the fields?  If they are also getting heavy it means you are not short of grass and to get things back in balance very quickly (so that you do not have the same problem on them by the time you get to graze them) you must take the grass off the heaviest paddock as soon as possible.  Most are doing this by round baling it, even if it means taking only a very small number of bales per acre off it.  By doing this that paddock is back into the rotation immediately, ready to be grazed again in a couple of weeks.

If you are short of grass overall then it gets a bit trickier i.e. you have one or two paddocks with a lot of grass on them and the rest have very little grass.  In this case you have little option but to graze them out as best you can.  Ideally strip graze them using a back fence and force them to graze it out as well as possible otherwise the re-growth is going to be problematic.  In some cases, topping the grass with a standard mower very low after grazing may be necessary (most toppers will not cut it low enough and will be only cosmetic at best) to get rid of that last stemmy material.  Dry cows / ewes may be used instead of mowing as they are not expected in many cases to gain weight.

Post-Grazing Covers - coming out of the ‘right’ covers = down to 4 - 5 cm 

Grazing Out Well

Apart from going into the ‘right’ covers of grass you should also be coming out of the ‘right’ covers if grass quality is to be kept up throughout the season.  These are what are called your Post-Grazing Covers.  There is a little bit of a chicken and egg situation with this.  If you are going into low covers it is much easier to graze those covers out very tightly (down to 4 to 5 cm).  If they are grazed tightly then the re-growth will have very little stem in it and the next time around you should be able to graze it tightly again.  However, if you are going into too heavy a cover it will be hard to graze out the field tightly.  Without a severe mowing/topping of what is left behind, the re-growth will then be stemmy making the next rotation even more difficult to graze out.  And so it keeps going on and on for the rest of the season.  The message is simple - if you start to let it slip and do not take corrective action early it is only going to get worse and worse as the year goes on.  The beef farmers who keep on top of this quite often never need to top fields.

Tightly Grazed Paddock below

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Laxly Grazed Paddock below

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The two pictures shown demonstrate the difference between tight and laxly grazed paddocks.  Both have mobile phones on their side to show the heights involved.  Just look at how green and leafy to the base the tightly grazed paddock is.  If this is grazed next time around at 8 to 9 cm it should remain with a very leafy, thick sward.  The other paddock has a lot of dead stemmy material showing that it has not been grazed out properly for a number of rotations and is now paying the price.

How much is it worth?

At many open days in Teagasc Grange over the years we have shown the target grass covers for going into and going out of.  We also put an estimate on what good grassland management is worth to a standard beef farm.  The figures are quite astonishing.  The difference per animal as a result of well managed swards is over 50 kg difference in liveweight on one to two year old cattle by the end of the grazing season.  Valuing this at even €2.00 per kg and stocking at a modest 2.5 animals per ha comes to a whopping €6,250 net margin on a 25 ha beef farm. 

If you gave a commitment of one hour a week towards achieving this for the 30 week grass season that is payment of over €200 per hour for that work. 

Answers on a postcard please for something else that pays better!

The Teagasc Beef Specialists issue an article on a topic of interest to suckler & cattle farmers every Wednesday here on Teagasc Daily  

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