Pasture residuals the primary tool

Date: 2010-05-10 | Category: Dairy News

Mike Guthrie, left, with Denise and Brett Larmer – production on track.

Mike and Parry described their emphasis on post-grazing residuals as the primary tool in regulating the use of supplements as top-up fodder. Without pasture-meters or feed budgeting with computers, the Te Ngaio team aims to get each cow up to 2kg/day milksolids (MS) and maintain as many as possible at that milking level until 31 May.

Post-grazing residuals proved controversial when 280 Grassland Conference participants met the Te Ngaio Farm tight five on a Bay of Islands dairy farm.

Farm owner Mike Guthrie, sharemilkers Brett and Denise Larmer, farm adviser Parry Mathews and pasture monitor Graeme Piggot presented facts and figures for the 430ha (400ha effective) property on Wakelins Rd, once home to the Lands and Survey, later Landcorp, Waitangi goat quarantine station.

Te Ngaio milks two herds of 560 Kiwicross cows through twin 52-bail rotary platforms.

One of the two 560-cow milking herds on Te Ngaio.

“You might call it manipulating the farm system at the coal face,” Parry said. He is a Palmerston North-based dairy farming consultant with about 30 percent of clients in Northland, where he travels every five weeks.

The grazing management approach at Te Ngaio is to put paddocks of no more than 2400-2500kg/ha dry matter (DM) in front of the cows and take that down to a carefully monitored 1200kg. High stocking rates of more than 50 cows/ha/day for short grazings and short rotations of 18-20 days in spring and summer are used.

By observing what has happened, plus or minus 1200kg/ha DM residuals, rather than trying to calculate intakes using pasturemeters and computer programs, cows are then topped-up to the required 17kg/day intake with maize silage.

Responsive

Adjustments to those supplementary intakes are made every few days, to be as responsive as possible. “Any shortfall in feed level is made up to the cows with maize silage on the feed pad to and from milking,” Mike said.

Up to 1.5 kg/day of grain-based meal is fed on the rotary platforms, and a further 2-3 kg maize is provided on the feedpads dependent on weather conditions and the estimated pasture DM supplied by the particular paddocks grazed.

DairyNZ farm system specialist Chris Glassey said the paddock in which conference delegates were standing, which Te Ngaio management said had been grazed the previous day, appeared to have considerably more than 1200kg DM residual, and other grassland specialists
agreed.

He said actual measurements using tools such as platemeters are useful to bring operators back into line with the goals of farm management. The danger in the Te Ngaio case would be overuse of supplements, with unnecessary costs financially and environmentally.

Parry and Mike, a former scientist, had also warned against going lower than 1200kg DM, to avoid damage to the ryegrass plants and pasture recovery.

Chris said there was plenty of evidence that consistent grazing to lower levels doesn’t harm the pasture, so the Te Ngaio team may be forgoing useful feed in the paddock.

That was particularly relevant when the Grassland Conference visited Te Ngaio after what was officially the coldest October since 1945, an irony not lost on conferencegoers who also discussed global warming.

The October pasture growth figures were only30kg/ha/day DM, when the demand exceeded 50kg, Perry said. The historical average for October on Te Ngaio was 60- plus under cage cuts by Graeme.

Winter-like

What should have been the one of the peak pasture production months for the year had instead delivered something closer to a winter growth pattern. It was quite a shock after a good, warm August and September.

Brett, nicknamed Stretch, said cows were getting around 11kg/day DM from pasture and 6kg from supplements, when at this time of year they should be on pasture mainly. The cost of supplements is around $1.50/cow, to maintain daily milk production of $10/cow.

The good news was that use of supplements had maintained production on track to around 520kg/ha MS by 12 December, which is officially halfway through the season.

At 1.9kg/cow, or 5.1kg/ha, Te Ngaio is doing about 90 percent more than the district average of 2.97kg/ha without a lot of supplementary feeding, Mike said.

Production has increased by 30,000kg MS every year for the past four years since the Larmers were first contracted. The property has broken through the 1000kg/ha MS barrier and the current objective is to get to 1200kg.

The farm is split into 80 paddocks of 5ha, with 200ha flat land and the balance low to rolling hills. Pastures are mostly ryegrass/white clover swards, with some kikuyu influence. The 2008 soil test results showed pH at 5.8-6.1 and Olsen P at 30-58, with an average of 41.

Mike Guthrie – former scientist, now dairy farmer.

Phosphate down

In the past seven or eight years, the phosphate content of the fertiliser applied has been reduced in favour of elemental sulphur and magnesium. Paddocks with less than pH 5.9 are targeted with extra lime as part of an annual application averaging 1.25t/ha.

As well as the lime, the fertiliser application for the current season will be a 50:50 mix of potassium chloride and urea plus selenium (Se) and cobalt (Co), applied in November to 270ha of clay soils only. This will deliver 23kg/ha nitrogen (N), 25kg/ha potassium (K), 0.5kg/ha Se and 0.3kg/ha Co.

This dressing provides part of the 150kg/ ha of N applied annually, usually in five dressings following behind the cows from May to November.

When the farm was acquired in 1992 an existing 28-bale turnstyle rotary dairy was upgraded to 34 bails. An additional new 44- bail rotary dairy and two maize pads were completed for the 1996 season.

Attempts to graze the cows in three or four smaller herds using 2ha paddocks not only proved inefficient in terms of movements to and from the dairies, but also resulted in poor grazing management, reduced pasture quality, inadequate production and high staff costs.

The move to 80 paddocks and the increased grazing pressure associated with two large spring calving herds has enabled production to climb above 1000kg MS/ ha with further increases in productivity considered possible, Mike said.

The 44-bail and 34-bail dairies were both upgraded to 52 bails at the beginning of the current season.

Cows get maize silage on their way to and from farm dairies, plus grain-based supplementary feed in the rotaries.

Fill gaps

The expectation is for a production level of 1200kg/ha MS through continued improvement in the quantity and quality of the pasture harvested by the cows. High quality supplements (turnips, maize and grain-based meal) are fed to fill seasonal feed gaps as they occur, and the elimination from the herd (now in its fifth year) of underperforming cows is continuing. Both herds are capable of being milked within two hours by a total of five staff members – four milkers and one yard
person.

With seven fulltime staff accommodated on farm, the daily routine can be managed with two staff on leave at all times. Half of the Waimate North runoff has now been raced and subdivided into 2ha paddocks with reticulated water, and it carries up to 200 dry cows during the winter with up to 150 yearling replacements. As many as 150 calves are transferred there in the late spring and 30ha of fertile river flats and easy contour is planted for maize silage. A further 150 yearlings are contract grazed near Puketi Forest.

A 100ha leased block on volcanic ground west of Waipapa also supports 200 dry cows over winter, followed by another 150 calves and 15ha of maize silage during the summer.

Denise rears up to 300 heifer calves each spring to provide herd replacements. Brett said the aim is to get the herd age down to eight years or younger and boost performance to 450-500kg/MS/cow. They are presently at 350kg.

Barkant turnips

The supplementary feeding includes 35ha of barkant turnips grown – yields have been excellent with 14t DM/ha achieved last summer – as a summer crop on the dairy farm, which leads to pasture renewal.

Turnips provide the milking herd with 4-5kg DM/day during the summer over 75 days from mid-December to early March. Then 45ha of maize silage (900 tonnes) grown on the runoffs is harvested when the turnip crop is finished, about one-third of which is used in the autumn as pasture levels fall.

Low-producing cows (less than 0.8kg MS/day) are progressively dried off to increase the quantity of pasture available for the better producers. This ensures the bulk of the herd is dried off in good condition after milking through to 31 May. In turn, this enables approximately 750 early calving cows to be wintered on the farm.

Pasture renewal starts with a winter-active ryegrass sown in the autumn, followed by the turnips and then permanent pasture early the following autumn. The three sprays of glyphosate seem to remove or suppress kikuyu effectively for at least five to six years, Mike said.

Recently two hill paddocks were regrassed with an experimental ryegrass/plantain/clover base mix at 17 kg/ha as part of a trial to investigate kikuyu suppression in Northland.

Published courtesy of Dairy Exporter December 2009

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