29 May 1998

Scalping excess grass is not right approach…

With an abundance of

grass on many farms,

Sussex herd manager and

FW Farmer Focus contributor

Christian Fox, gives some

tips on how best to manage

heavy grass covers

WHEN faced with too much grass, theres a temptation to commit forage suicide and cut the whole lot for silage.

But scalping the whole farm is a drought-inducing strategy, reducing growth and removing the grass feed wedge which is key to maximising use of grazed grass. In short, take too much from in front of the cows and you will end up feeding it back during the summer as a second rate feed, or using cake – which adds up to expensive farming.

Feeding cows very long grass will almost certainly compromise quality when not grazed tightly and affect milk quantity when grazed too hard. So how can we manage this critical period? It is not as difficult as it seems, providing you remain focused on the key issues of pasture quality and availability.

Maintaining quality is the key to maximum pasture use. Everything you do now will affect your ability to provide palatable, nutritious, leafy grass in about a months time. This effect is cumulative. Two or three lax grazings of a paddock and you are looking at poor quality autumn feed. Get that wrong as well and next season its time to work out what your cows and quota are worth.

As for pasture availability, you cannot graze consistently throughout the year if you fail to keep a decent wedge of grass. This means having grass ready to graze – 2500-3000kg/DM/ha – at the top of the wedge and yesterdays paddock – 1400-1650kg/DM/ha – at the bottom of the wedge.

So, removal of excess grass, given that silage requirement will be met in the usual way, is purely a matter of maintaining quality and availability. But how should this be achieved?

A good starting point is to measure daily growth rate. Is it greater than your intake requirement or less? Is it increasing or decreasing? This will determine your course of action. When growth is slowing down or below intake demand, be prudent. Remove too much and you will run out.

When growth is in excess of intake requirements, restore the correct feed wedge and get on with the rotation. Strip graze tall grass for too long and it grows back behind you. You end up sacrificing sward quality and milk quantity and still end up cutting. Use growth rate and average farm cover information to help management decisions.

Strip grazing and back grazing as a tool to cope with high grass covers are usually big no-nos as they slow regrowth of the sward and flatten your feed wedge – it becomes too long in one paddock.

But in a very tall cover situation – more than about 4000kg/ DM/ha – strip grazing can be a useful technique to keep the cows grazing.

Dry cows or youngstock can be used to tidy up after the cows have creamed off the better quality material. In tall covers – 3500-4500kg/DM/ha – allocate a fresh area for cows every 12 hours to prevent too much spoiling. Allow the dry cows or youngstock to tidy each paddock for one day or at the most two.

They should be stocked sufficiently to bring the residual down to a maximum of 1700kg, and preferably nearer 1500kg/DM/ha. Increase stocking density by putting heifers and dry cows together rather than sub-dividing paddocks into small areas. This, together with excessive back grazing, will cause difficulties when you want to return with the cows, only to find insufficient regrowth (back grazing) or varying cover (excessive subdivision).

Obviously, if you cannot remove the excess grass by grazing alone you are forced to resort to machinery. If you are resigned to mowing paddocks, why not mow the grass, wilt it for 24 hours and let the cows do the rest? This is especially useful if you already have enough silage or the clamps are full. Only cut a 24-hour area each day. Even when in the middle of silaging this is a useful technique.

When the excess grass is such that cutting and removing is the only option, then consider trying to restore the feed wedge by staging the cutting so that not too much is removed at once. This is only really practical if you are able to round bale the resulting silage.

Remember that the reason for doing this is to restore the feed wedge and maintain sward quality. The quality of the round bale is of little importance, it is not your main winter feed and can be fed back to dry cows or used as a carrier for magnesium/minerals around calving time.

Heavy grass cover on the farm is only a problem because it compromises quality for the rest of the season.

The key to managing it is overcoming inflexibility, not of the farm, machine or cow, but man.

When grass is very tall strip grazing can be a useful technique to keep the cows grazing.

Christian Fox… the key to managing heavy grass cover is overcoming inflexibility – not of the farm, machine, or cow, but man.

MANAGING EXCESS COVER

&#8226 Strip and back grazing.

&#8226 Leader/follower system.

&#8226 Mow ahead of cows.

&#8226 Round bale in stages.