early and on grass

27 February 1998

Get em out

early and on grass

Making the most of grazed

grass is the theme of beef

specialist Basil Lowmans

seminar at the Beef Event.

Sue Rider reports

EARLIER turn-out of beef cattle to maximise use of grass and reduce reliance on silage must be a priority for the coming season.

Basil Lowman, beef specialist at the SAC, urges producers to end their fascination for silage. "We must revise our priorities and maximise production of our cheapest, most marketable feed – grass. Silage should revert to the role of a grazing tool to help us manage grass," explains Dr Lowman.

He says current cereal prices make silage less attractive, and it is certainly more expensive than grazed grass. This is three times cheaper than silage, and making better use of grazed grass – for example, to reduce winter housing by three weeks – could cut production costs a kg liveweight gain significantly.

Grazed grass costs about 30p/kg liveweight gain, compared with silage and a little barley at 75p/kg, so think about an earlier turn-out and onto fields that can still be cut for silage, says Dr Lowman. "Silage yields will be lower, but quality better – and the eventual loss in yield will be far less than the silage the cattle would have eaten inside."

Dr Lowman cites Irish research to show that although early grazing of silage fields reduced first cut yields by 15%, second cut yields increased by 8%. The lighter first cut left a greener, denser aftermath, which recovered more rapidly. If a second cut of silage is not taken, then there would be more aftermath grass available for grazing, he adds.

The D-value of the first cut, which had been grazed first, was about 2-3% higher. The early grazing removed dead grass carried over from the previous autumn, leaving a leafier crop. This allowed cattle to perform better over the summer – being 12kg heavier when they were housed the next autumn.

Overall, early turn-out showed a financial benefit of about £20 a head.

The critical point in the system appears to be the date on which grazing cattle are removed from silage fields. "As a general rule of thumb, this should be at the same time that cattle would normally be turned out," explains Dr Lowman.

Irish research suggests applying fertiliser six weeks before turn-out. For areas of later grass growth, Dr Lowman suggests turning out cattle on to silage ground about six weeks after T-sum 200, and removing them from the silage fields three weeks later – nine weeks after T-sum has been reached. For the SAC Craibstone Farm, Aberdeen, average turn-out date would be Mar 8, making proposed date of early turnout Apr 18 and removal from silage fields – three weeks later – would be May 10.

Having turned out early, it is important to ensure grazing cattle are well fed to maximise output from grazed grass. Dr Lowman advises aiming for at least 1t of liveweight gain/ha. Maximising output off grass depends on ensuring the animal can eat as much as possible in every bite, he says.

"Whats important is bite size – and we know optimum intake is at 8cm grass heights."

So to ensure cattle can sustain high growth rates to finish off grass, it is essential that grass heights are maintained at the target of about 8cm (3in) through to late July. Allow grass to get any shorter – below 7cm (2.75in) – and cattle cant eat enough grass to meet their requirements, resulting in low liveweight gains (see table). Similarly, for the second half of the grazing season, Dr Lowman suggests target grass heights should be allowed to in-crease slightly to nearer 10cm (4in).

"This will avoid cattle having to graze down into the dead material at the base of the sward which will have a feed value no better than straw."

The difficulty is how to achieve these target sward heights, especially given the seasonal variation in grass growth. Dr Lowman recommends a set stocking and buffer grazing system to manage the grass.

He acknowledges that paddocks can work for some all-grass farms, and do make management easier – but at what cost, he asks.

"Erecting paddocks is an expensive operation. Silage making becomes more and more expensive as we bring more fixed costs into the system – we mustnt run the risk of going the same way with grazed grass.

"Set stocking and buffer grazing gives all the flexibility we need," says Dr Lowman. "Its basically a two paddock system, with normal numbers of stock allocated to each grazing field, but before cattle are turned out a temporary electric wire is erected to fence off about one-third of the field – reducing the size of the initial grazing area."

Cattle graze the remaining area, explains Dr Lowman, who recommends an initial target stocking weight of about 3000kg of beef/ha – for example 10 300kg store cattle/ha at turn-out.

Height of grass in the reduced grazing area is then monitored weekly. If the height of grazed grass remains on target, the grass behind the electric fence is cut as a bonus crop. "This is the grass which otherwise would have been wasted and would have had to have been topped in late June," says Dr Lowman.

If grass height falls below target the electric fence can be moved back to supplement the original grazing area, he adds.

In situations where the grass in the buffer area is too long to graze, it should be cut and grazed by mowing down two or three swaths parallel to the electric fence. The electric fence is then moved, one swath at a time and placed in the centre of the swath – acting as a feed barrier to reduce waste.

As grass growth declines later in late summer, Dr Lowman recommends supplementing cattle. "We must start supplementary feeding cattle at grass in autumn – Irish research has shown that this strategy is extremely cost-effective – more than doubling carcass gain a day." &#42


&#8226 Cheapest and most marketable feed.

&#8226 30p/kg lw gain,75p/kg lw for silage.

&#8226 Graze fields then cut for silage.

&#8226 Set stocking plus buffer grazing.

&#8226 Consider supplements in autumn.

Effect of grass height on performance of grazing cattle over the summer grazing period (kg/day)

Effect of grass height on performance of grazing cattle over the summer grazing period (kg/day)

Sward height May- July- Sept- June Aug Oct

Low (7cm) 0.45 0.63 0.92

High (10cm) 0.66 0.81 0.75

Basil Lowman… "Revise your priorities and maximise production off your cheapest and most marketable feed – grazed grass."

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