17 May 1996

Wise grazing decisions now will help in future

Low growth rates are now putting grazing under pressure. Large areas taken for first-cut silage will further delay cover on the farm and impose a self-created early summer drought.

Mark Blackwell reports

FROSTS and lack of rain in early May have kept grass growth below expectations and increased pressure on grazing.

The grass shortage is worst on those farms running high stocking rates. These are being maintained so it is possible to make the tonnes of silage everyone believes they need for winter.

The effect is that during periods of lower-than-expected growth like now, pasture availability declines rapidly to the point where it is necessary to go into silage-length grass to keep the cows fed.

Grazing some of the silage is fine but it will be too long for efficient grazing.

Producers using continuous or set stocking together with high stocking rates have least flexibility to accommodate periods of slow growth. Those with a moderate stocking rates plus a rotational system seem to be better off.

At the same time that the grazing area is under greatest stock pressure, first-cut silage is taken, further depleting pasture cover on the farm.

Silage aftermaths have the potential for a self-created early summer drought. Producers will perceive the need to feed the conserved silage out no sooner than it is in the clamp.

So whats to be done? Some silage area can be grazed or cut and fed at grass. But those are far from ideal ways to manage pasture.

Despite the frosts, growth has not stopped. It is still vital to monitor the grass situation daily to assess what is happening. The aim is to balance daily feeding with the current grass feed supply. Judgements must also be made about future growth rates, and about the speed of grazing rotation.

Take a weekly farm walk scoring the amount of feed in all paddocks or fields. Include the silage areas in this as well.

At a glance there are two distinct grass growth periods in spring (see graph).

&#8226 Early spring: Grass growth is slow relative to the cows pasture feed demand. Cows are capable of eating grass faster than it is growing so grass cover on the grazing area declines.

&#8226 Late spring: Grass growth exceeds the total feed demands. The cows grass intake is outstripped by high growth rates. Grass cover on the grazing area builds up during this period because growth exceeds consumption.

But in reality growth is not consistent as the graph shows and the two periods are not defined so clearly.

In early spring the critical issue is securing the maximum pasture growth, so cows can be fed directly on grass as much as possible.

This means grazing grass infrequently, with a long rather than a short grazing interval. Allow grass to get to a length at which it is in its most rapid growing phase.

In the second period the critical issue is managing a surplus of pasture feed, controlling pasture quality, and making the right silage decisions.

At this stage the grazing interval is not so important. What is important is grazing height, to remove a good proportion of the developing seed heads. Set stocking can be appropriate a this time. But often in the UK farmers reduce the available grazing area to such an extent that cows are stocked at between 6 and 8 cows a ha (2.5 to 3.25/acre).

Grass being wasted because cows are on silage and concentrates, Mark Blackwell (centre) told farmers visiting a Welsh College (See below).