22 June 2001

Good grazing quality can protect dairy cow yields

By Hannah Velten

MAINTAINING summer grazing quality, sometimes at the expense of silage area, is essential to prevent declines in dairy cow yield, particularly on dry farms.

Slow grass growth this spring, followed by a growth explosion means many farms have lost control of the grazing area, says Pasture to Profit dairy consultant Carol Gibson. "Now is the time to clean up pastures to rebuild quality. Cattle will not graze seeded or dead pastures later on."

Topping, using a mower, after grazing will bring life back to swards, she adds. "The aim is to cut low enough so it comes back like silage aftermath – leafy regrowth, which provides high quality grazing.

"However, paddocks will often take about five days longer to recover and nitrogen must be applied when grazing is limited," she says. Alternatively, dry cows can graze low quality grazing out hard, but generally a quicker rotation of paddocks will generate a better quality sward.

During summer, cows should have feed in paddocks ahead of them, but not so much that grass is seeding, says Miss Gibson.

"Grass growth will vary depending on the weather and may slow throughout June and July, from 60kg DM/ha/day to 50/40kg. But average pasture cover should be kept at about 2200kg DM/ha or 7-8cm high."

When grazing is limited, take out some silage area to use as pasture, advises Miss Gibson.

"Most people will be focused on silage-making after last years low reserves, but there is no point making silage as a second cut and then having to buffer feed cows."

When pasture is getting long it may be tempting to shut the field for silage. But producers concerned about grass shortages later in the season can skip these paddocks in the rotation and return to them when needed. "The grass will probably be too strong for cows to graze it properly, so either top it after they have grazed or cut and wilt grass before grazing.

"Treat the latter process like silage making. Mow in the morning and wilt in the afternoon, but only enough for that day and avoid doing it in wet weather," she says. Using this method for nightly feeds will buy a little more growing time for other paddocks.

Areas of low rainfall will probably experience harder times in summer months. Miss Gibson advises avoiding taking large areas of second cut and too much topping, as this will burn off any available grass.

"Preparation is essential to cope with dry periods. Allow pasture cover to rise to 2500-2600kg DM/ha and slow the grazing rotation before dry weather is expected, so intakes can be maintained during this period."

Grazing should last the season by putting on nitrogen, keeping cows on a 30-day rotation instead of the usual 15-21 days, using silage aftermath paddocks and buffer feeding, when necessary.

"When rain begins and pasture cover is back to about 2200kg/DM/ha, return to a quicker rotation," she adds. &#42

SUMMERGRAZING

&#8226 Use silage area when necessary.

&#8226 Top seeded or dead pastures.

&#8226 Prepare grazing for dry times.