7 June 1996

Consult your wedge for answers to feed regime

Feed budgeting of grass need not be too difficult reports Mark Blackwell

FEED budgeting of grazed grass is critical to estimate how many days feeding can be achieved at a desirable intake level. It involves assessing yields of grass on paddocks at regular intervals.

The farm cover of grass is the average yield of grass on all paddocks – those about to be grazed and those just grazed. The profile of that varying grass cover is known as a feed wedge (see diagram).

The top of the wedge is where the cows should be grazing (at 2500-3000kg DM/ha), unless that grass has got too long and the area is dropped out for silage.

The bottom of the wedge is where the cows have just been grazing. The amount left behind here tells us a lot about how the cows have been fed recently.

The shape of the feed wedge varies throughout the year depending on grass growth and management, such as changes in frequency and intensity of grazing, and silage making. When the farm is in continuous grazing or set-stocking, the feed wedge is virtually flat, and not wedge-shaped at all. In a rotational grazing situation the wedge is more obvious.

The feed wedge has a number of advantages. Assessing the amount of feed a the top end of the wedge allows you to manipulate the feed on offer to the cows day by day.

First you can see the grass that is available on the farm. You can see tomorrows feed and next weeks feed by looking ahead, further down the feed wedge. Immediately behind the cows you can determine current growth rate.

With 2500-3000kg DM/ha of grass cover this field is an ideal example of the top of the feed wedge where cows should be grazing, NZ adviser Mark Blackwell tells a farmer meeting at Robin Hoares 283ha (700-acre) Lympsham Manor Farm, Lympsham, Weston-Super-Mare, Somerset.