Seed company DLF is running trials on David Hunter’s dairy farm in Newtownstewart, Co Tyrone, to see which grass varieties cows prefer to graze.

At an Ulster Grassland Society (UGS) event on Tuesday, Damian McAllister from DLF showed how plots of different grass varieties were established in a paddock on the Hunter farm in 2023.

Grass is measured in each plot before grazing, the cows are turned into the paddock to graze it as normal, then post-grazing covers for each plot are recorded afterwards.

“It is all about utilisation. Rather than focusing on tonnes of dry matter grown, we are looking at tonnes of dry matter utilised,” Damian said.

The trial has found grass utilisation rates range from 68% to 82% and the results help DLF decide which new varieties are best suited to the likes of grazing or cutting mixes.

In general, the trial has found that plots sown with tetraploid varieties tend to be more palatable than most diploid varieties.

Tetraploid grasses usually have larger, softer leaves and have higher sugar content than diploids.

Open swards

However, swards sown only with tetraploid varieties can be more open which can make for difficult grazing conditions in a wet time.

Damian said there is variation in sward density across tetraploids, as some varieties produce swards that are much denser than others.

“We want to find that sweet spot where we have the density of a diploid but the graze out of a tetraploid,” he said.

DLF has also trialled multi species swards on the Hunter farm and UGS members were taken to a herbal ley that was established four years ago.

All the herbs have disappeared, and the sward is now just made up of perennial ryegrass and white clover.

“The moral of the story is don’t be afraid to try multi species mixes. If the herbs eventually go, then clover will take its place so you will still be left with a good sward,” Damian said.

“The soil in this paddock should be in a better place because the herbs were there for a few years. They have deep tap roots which open the soil up and help soil biology,” he added.

Plans to lift cow numbers after land purchase

David Hunter is currently milking 112 spring calving cows on his farm near Newtownstewart, Co Tyrone.

Cows are averaging 6,925 litres at 4.65% butterfat and 3.71% protein from 1.85t of concentrates.

Around half the herd calves down in the first three weeks of February and all cows are calved within a 12-week window.

His crossbred herd is currently made up of Holstein Friesian and Jersey genetics, although all heifers coming in from next spring are sired by Viking Red bulls.

The Hunter farm has free-draining soils which allows cows to go to grass during the day by mid-February and grazing commences full-time once grass growth permits.

At the UGS autumn farm walk on Tuesday, it was notable how much grass was still available across the grazing platform.

“The cows probably have three weeks’ grazing ahead of them. Whether ground conditions hold out for that length of time is another thing,” David said.

Grass supplies are strong because the milking herd has been housed by night since early October and stocking rate is lower than usual due to land being purchased last year.

Cows can walk to the new 24ac block and David has invested in reseeding and grazing infrastructure to make it suitable for the milking herd.

He explained that the new ground has left his grazing platform at a stocking rate of three livestock units per hectare (LU/ha), which is lower than normal.

“I have had the stocking rate up as high as 4.5 LU/ha in the past, but I found I was chasing my tail a lot of the time. The grazing round was as short as 14 days and I had to buffer-feed silage when things were tight,” David said.

The plan is to lift the current stocking rate to around 3.5 LU/ha, which means increasing the herd to 130 cows. “It should be a comfortable number of cows for this grazing platform,” David said.

Reseeding, soil fertility and making silage

All of the Hunter farm has been reseeded within the past 10 years and min till techniques are the preferred method of reseeding.

David told UGS members that ploughing is occasionally carried out if necessary, but he tends to just burn off an old sward, then power harrow it before drilling.

He has tried direct drilling without any harrowing in the past but has found it to be “hit and miss”.

There is a big onus on soil fertility, with all land analysing over 6 for soil pH and the aim is increase this to 6.5.

Ground lime is mostly used at reseeding, and all land gets an application of prilled lime each year for maintenance.

Indexes for phosphorus and potassium were low when the farm converted from sucklers, sheep and arable in 2013, but indexes have slowly built up through targeted use of slurry and fertiliser.

Since getting a dribble-bar slurry tanker, David has been able to make more use of slurry on the grazing block.

All paddocks get slurry in February, and most grazing ground usually gets another application during the summer.

David said he has had no problems with slurry drying out in lines on top of the grass although he acknowledged that his slurry tends to be fairly watery, with plenty of parlour washings and yard run-off going into tanks.

Other recent investments include a GPS fertiliser spreader.

“There are big savings with it because you spreading with more accuracy. It is really useful for those smaller, awkward-shaped paddocks, and not just the big fields,” David said.

First round

Urea is applied in the first round in February, with compound fertiliser used in the second round, depending on soil analysis results. After that, straight nitrogen and sulphur is used for the rest of the season.

Despite operating a spring-calving system, David still aims for good-quality first-cut silage as he feeds milking cows by night during the early spring and late autumn.

This year’s first cut analysed with a metabolisable energy of 11.3, dry matter is 38%, crude protein is 13.5% and D-value is 74.6.

After first cut in early May, a bulkier crop for dry cows is harvested in late June, and then a good-quality third cut is made in August for young stock.