5 June 1998

SPRING PADDOCK SYSTEM IS THE NEW GRAZING STRATEGY

Pressure on profits has made many producers more aware

of grazing this spring. Jessica Buss joined a grassland

discussion group to see how one producer is coping with

his new grazing management policy

DESPITE cutting silage from the grazing area, grass will be plentiful for the next grazing round on one Cheshire farm.

Mike Allwood, Burland Farm, Nantwich, has changed his grazing policy this year. Grazing fields have been split into 2-2.4ha (5-6 acre) paddocks and milkers are being offered a fresh block after each milking. Previously the 4-4.8ha (10-12 acre) fields were grazed in rotation for as long as necessary to graze the grass available.

In late May this year, 110 milkers were taking three and a half days to block graze a paddock. Milkers included about 30 May calvers and late lactation cows. The rest of the 180-cow herd, which averages 6800 litres from 1.7t of concentrate, were dry and due to calve between May and July. Fresh calvers receive concentrate – up to 8kg for the few 40-litre cows in summer.

Mr Allwood told a BGS grass discussion group meeting that his key concerns were: Is the grass cows are grazing the right height and quality, how can weight loss in his fresh calvers be avoided to ensure good fertility, and is the amount of grass left behind after grazing acceptable?

When he cut silage on May 18, he selected the two grazing paddocks with the most cover because grass was getting ahead of cows. These had been grazed once since turnout on March 15.

"We are now on our second grazing round and are battling with grass that is too long, but are unable to do much other than tidy up the field by grazing," says Mr Allwood. More cows are calving and cows may run short of grazing before silage aftermaths recover if more silage is made. He also expects grass growth rates to fall because he has began organic conversion and cannot apply any inorganic fertiliser.

Estimated cover

The group estimated the grass cover of the paddock being grazed at 3000kg DM/ha (1200kg/acre). Carol Gibson, BGS grazing consultant from New Zealand, measured the paddock using a plate meter. She found the cover was nearer 3900kg DM/ha (1600kg DM/acre). "Grass which is lying over indicates a cover above 3500kg. The ideal cover for grazing is 2500kg to 3000kg, to ensure high quality grass and good intakes."

The grazing acreage for the next round of about three weeks was 15ha (37 acres) and milking cows would average 125. Stocking rate on this area is nine cows/ha (2.4/acre) and Miss Gibson advises aiming for grass intakes of 18kg DM with fresh calvers, but the average for the group would be nearer 16kg a cow in this grazing round. The demand, therefore, is for 144kg DM/ha (58kg/acre) a day, and growth rates should exceed 80kg/ha (32kg/acre) a day.

That indicates more grazing area is needed to keep on grazing, but the high level of cover now meant that the high stocking rate was not a concern for this grazing round – after which aftermaths will be available. With grass growth rates of only 40kg DM/ha (16kg/acre) a day in August, Mr Allwood could maintain grass intakes at this level for 180 cows because cows can graze 70ha (175 acres), says Miss Gibson.

Mr Allwood was not concerned about losing cow yield as much as infertility, if cows lost weight. He had bought maize silage for buffer feeding in summer. Cows had lost weight particularly in August and September over the last two years, although grass was usually available cows had not performed well on it. However, Mr Allwood admits that he is unsure of the benefits of buffer feeding.

But Miss Gibson recommends focusing on the grazing above deciding whether to introduce a buffer. "This is the time of year for growing and feeding grass, the maize silage can be fed anytime." Aim to maintain grass quality. There is no reason for summer and autumn grass to be poor quality, she adds.

Quality regrowth

Cows must graze down paddocks tightly to ensure quality regrowth. Following cows with other stock or topping could be used when necessary to reduce grass covers after grazing. But it is difficult to know how much cows should leave behind in a paddock after grazing – there would always be areas grazed tightly and rejection. Miss Gibson admits there is a compromise between grass intakes and milk yield now, and quality of grass for the next grazing rotation.

"However, cows should graze well between rejected clumps and have grazed the tops off over the clumps. This leaves a residual grass cover of 1700-1800kg DM/ha."

Mr Allwoods cows could be grazing a little tighter, as the covers being left were nearer 1800kg DM/ha (730kg/acre).

"When leaving less than 17-1800kg DM and making silage more should be grazed, but when leaving more you should be silaging more," says Miss Gibson. &#42

There is still plenty of grass ahead of Mike Allwoods cows. Carol Gibson(right) measured cover on this paddock at 3900kg DM/ha.

GRAZINGADVICE

&#8226 Grass that is bent over is over 3500kg DM/ha.

&#8226 Graze tightly so cows take tops off clumps.

&#8226 Focus on maintaining grass quality and avoid buffer feeding.