Many commercial farmers are sowing monocultures or single grass varieties, instead of a mix of four or five grass varieties. They are aiming to pick the highest yielding and best quality variety they can get to maximise output.

If you were to sow a single variety, would you sow the grass with or without clover? Would the clover bring any benefit in terms of milk yield? Would the grass variety yield higher with the clover in the sward?

These are some of the questions Teagasc Moorepark is attempting to answer in a six-year study started at Clonakilty Agricultural College.

Last year, the farm in West Cork was sown to monoculture tetraploid and diploid grass varieties with and without clover. Four tetraploid varieties – Aston Energy, Kintyre, Dunluce and Twymax – were sown as single varieties (not a mix) and each variety was sown with and without clover. The same happened with four diploid varieties – Tyrella, Drumbo, Aberchoice and Glenveagh. Each was sown with and without clover.

It means there are four treatments on trial:

There are 30 cows grazing each of the four treatment stocked at 2.75 cows/ha, so there are 120 cows in total in the trial and it takes up 44ha of the 84ha farm in total.

The rest of the farm is used for grazing a general herd that is primarily used for teaching students, rearing replacements and silage.

The aim is to assess the grass varieties and the varieties with clover over a full grazing season for milk, dry matter yield and grass quality.

The cows in the trial are a mix of Holstein Friesian, Jersey cross and Jersey/Holstein/Norwegian Red cows.

Grazing management

The target pre-grazing yield and residual are the same as any good commercial farm. Aim for a 1,200kg to 1,500kg pre-grazing yield.

Clean it out well to 4cm, take out the surplus as bales when it arrives and, if there is grass scarcity, feed a bit of meal.

Interestingly, there is 250kg of bag nitrogen used across all treatments. Some scientists would argue that, over time, this will kill the clover in the swards.

Results

The results for 2013 are available but because it was the middle of the year before the trial got under way, the researchers are suggesting that 2014 is really the first year of the trial. However, the 2013 results show the grass and clover swards outperforming the grass-only varieties (Figure 1).

There were higher dry matter yields 0.5t (or more) with the clover swards and higher milk solids yields (10kg to 20kg MS/cow). If these results can be repeated over the coming years and the clover maintained in the sward in 2014, it will be very interesting. At a value of €5/kg milk solids, the milk output value per cow alone would be €100 at little or no extra cost.

2014 performance

So, what is performance like to date this year? As you can see in Figure 2, the cows in the clover groups were yielding between 0.13kg and 0.18kg of milk solids extra per cow per day in early May. This was coming mainly in extra volume (about two litres per cow) and slightly higher protein. The cows grazing the mixed grass and clover swards have delivered, on average, 10kg of milk solids more per cow in the first 90 days of lactation.

As Brian McCarthy and Fergal Coughlan showed us last week, the cows are grazing out the swards very well. The tetraploid varieties, in particular, are grazed to the floor and the cows are completely content grazing them out. We walked into one trial group of cows and they were in their third and final grazing in the paddock about two hours before evening milking. There was little or no grass in the paddock. The dungpats were well clipped but the cows hardly lifted their heads to see who was walking in the gate.

While the cows looked empty, Fergal Coughlan explained it was simply empty gut fill. Fat reserves on the cows are good, with the herd averaging three in body condition score.

He explained that the cows would be going into a new paddock of grass after evening milking and, if we came back in a few hours, the cows would be full up with grass.

With the farmers present, there was a good debate about the issues around maintaining and managing clover in the sward and the dangers associated with too much clover.

Researcher Brian McCarthy explained they never have a problem with bloat in the cows and he feels it’s because the cows are accustomed to the mixed grass/clover swards all year.

He said: “When clover explodes in the autumn, we feel the cows can handle the high clover diet, even when they are grazing the paddocks well. Last autumn, the milking cows went into swards with 60% to 70% clover – it’s simply a mass of clover.”

At sowing, there was only 2kg of clover per acre included with the tetraploid or diploid grass seed and, from walking through the paddocks, it is clear that there is good clover content in the swards.

This week, the cows on the mixed clover/grass paddocks are grazing paddocks with 25% to 30% clover.

Clonakilty update

In total, 193 cows calved this year and there are now 179 cows being milked. Two cows died, eight cows were sold after they calved, while another three cows have been dried off early and will be sold. There was one abortion.

Cows are milking 22.8kg/day (1.87kg MS/day). The latest results from the processor are 4.45% fat, 3.51% protein, 4.94% lactose, 76 SCC (somatic cell count) and 3 TBC (total bacterial count). Breeding started on 20 April and is going well. Approximately 156 cows were served in three weeks (87%), and 47 out of the 49 heifers were bred to artificial insemination (AI) in the first 11 days of the breeding season. Two Friesian bulls have now been let off with the heifers.

Last year, this new and exciting trial started on the Clonakilty Agricultural College farm and it is already putting Clonakilty on the map as one of the best grass trials Teagasc has up and running. The bottom line is, can the clover be maintained in the sward and how will the trial play out for the next five years? The five-year result is the real result for this trial.

Even if the trial results remain positive, the research work is only starting and there are still plenty of questions to answer. A lot of clover farmers have had a mixed relationship with grass/clover swards.

Some of their challenges included not having enough dry matter in the spring, bloat and cow deaths when clover takes over from mid-summer onwards, clover dying out of the sward and an inability to manage other weeds, such as docks, that develop when clover is established.

The challenge for the Teagasc researchers is to answer these questions.

However, if we leave aside the grass/clover results, it will also be interesting to see the milk and grass dry matter difference in Clonakilty performance if a farmer sowed a paddock to a pure tetraploid or diploid variety.

Farmers are advised to sow only 40% to 50% tetraploid in a mix of three or four varieties.

However, if a farmer could select the best tetraploid or diploid variety that has been trialled in Irish conditions, why not sow it on its own? The farmer should know exactly what it will deliver, how it should be managed and what to expect for his/her investment. Some of these questions listed above have been with us for a while and it’s time to start getting answers.