Pay heed to grass and clover varieties when choosing multispecies swards

Numerous studies have shown the benefits of multispecies swards relative to a perennial ryegrass only sward. These include increased animal and sward performance, reduced requirement for artificial nitrogen application and reduced need for anthelmintic drenches.

At last Friday’s Growing Organics farm walk on Jason Stanley’s farm in Co. Laois, Dr. Philip Creighton, Sheep Enterprise Leader at Teagasc’s Animal and Grassland Research and Innovation Centre, Athenry, presented results of studies carried out in the research centre over the last number of years.

Giving a background, Dr. Creighton said: “Multispecies is well proven at this stage in that it will finish lambs faster, there is no debate on that. But there was still a few questions around the establishment and persistency of it.

“There were issues in terms of the persistency of some of the components of multispecies swards. The idea of this study was to see can we tease out what parts of the sward were lasting the longest or which were maybe not lasting quite so long, and what was the effect of that and what benefits did it bring in terms of lamb performance.”

To answer this question, one study compared a perennial ryegrass sward to binary sward mixtures of perennial ryegrass and one companion forage. Both sward and animal performance were examined under an intensive sheep production system.

The sward types under investigation were: perennial ryegrass (PRG); perennial ryegrass and white clover (PRG+WC); perennial ryegrass and red clover (PRG+RC); perennial ryegrass and plantain (PRG+Plan); and perennial ryegrass and chicory (PRG+Chic).

Results

The addition of any companion forage significantly improved lamb lifetime average daily gain (ADG). As a result of improved animal performance, average days to slaughter was reduced by 19, 28, 15 and 28 days, respectively, for lambs grazing PRG+WC, PRG+RC, PRG+Plan and PRG+Chic relative to lambs grazing PRG, which took 228 days to reach the appropriate slaughter weight.

“When we look at them in isolation, the red clover (PRG+RC) and chicory (PRG+Chic) swards provided much higher levels of animal performance in our trials. It reduced days to slaughter by nearly a month when compared to perennial ryegrass only and this is over a four-year period. This isn’t one snap shot, this is a longer term study,” he explained.

Furthermore, reductions in days to slaughter led to reduced rates of concentrate supplementation required where average concentrates consumed per lamb drafted was reduced by 6.1, 11.3, 8.2 and 10.7kg concentrates/lamb drafted for lambs grazing PRG+WC, PRG+RC, PRG+Plan and PRG+Chic respectively relative to PRG, which consumed 14.2kg concentrates/lamb drafted.

Carcass weight, carcass conformation, fat score and kill out percentage were similar across all sward types.

Average annual herbage production was 11t DM/ha, and was similar across all sward types. Annual grazed herbage yield was 9.1 t DM/ha and silage herbage yield was 1.9t DM/ha, which were also similar across all sward types. For this study, all sward types received the same amount of inorganic nitrogen; however, studies have shown that similar levels of herbage production can be achieved from grass and clover swards at lower nitrogen application levels, relative to a perennial ryegrass only sward receiving higher nitrogen application levels.

Challenges

Challenges exist around the establishment, management and persistence of companion forages within sheep grazed swards and for that reason, a number of plot-based studies were carried out in Athenry to try to improve companion forage persistency within a sheep grazing system.

One of these studies (figure 1 below) examined the effect post-grazing sward height had on the persistency of the companion forages; three post-grazing heights were employed – 4cm, 4.75cm and 5.5cm. A post-grazing sward height of 4.75cm was found to be the happy medium.

On this, Dr. Creighton said: “There was a school of thought that you had to graze these swards very lax and keep the post-grazing height up very high. We had concerns about that in that you were keeping the post-grazing heights very high to suit one or two components of the sward, while maybe having a detrimental effect on the overall quality of the rest of it.

“Interestingly, what we found was that if we go to the standard intensive grassland post-grazing sward height of 4cm, it was wiping out red clover. At a post-grazing sward height of 4.75cm, it was having a beneficial effect in all cases in terms of keeping the sward components at the end of year three.

“Interestingly, when we went lax at 5.5cm, it had a detrimental effect because we never cleaned out the sward fully. It was causing a lot of dead material to build up and it was shading out the plants.”

Figure 1: Companion forage content in a three-year sward (2022) by post-grazing sward height

Seeding rate

The Sheep Enterprise Leader also commented on seeding rates for multispecies swards, adding: “When we started the study first in 2018, there was very little information available in terms of the appropriate sowing rates for establishing the sward.

“At first, we were getting relatively poor levels of companion forages. There were two reasons for that. We were putting too much grass in and we weren’t putting enough of the other forages in with them. There was too much competition and we were penalising the companion forages from the start.”

To shed more light on the optimum seeding rate, a study was carried out examining low, medium and high seeding rates (table 1).

Table 1: Seeding rates applied in seeding rate plot trial

The low seeding rate was sufficient for a PRG+WC sward, the medium seeding rate was sufficient for a PRG+Chic sward and the high seeding rate was needed to achieve sufficient levels of companion forage content in PRG+RC and PRG+Plan swards.

Figure 2: Companion forage content by seeding rate

Commenting on the results, Dr. Creighton said: “For the white clover treatment, it was relatively consistent at the low, medium or high seeding rate.

“However, for the red clover, chicory and plantain, they all benefited from moving from a low seed rate. The plantain and red clover benefited from going to the highest rate. There was less completion, which resulted in higher levels in year two and three of the trial, which meant we had those benefits for longer.”

Although some farmers are critical of multispecies swards’ ability to retain all of its components for an extended period of time, Dr. Creighton pointed to the positives.

“By having these swards – even if some of the components last two years – will still provide us with much higher levels of lamb performance. When they start to drop out, we still have a higher level of performance from the white clover and perennial ryegrass that is left.

“If you are establishing these swards make sure that you are putting in good varieties of grasses and white clover to ensure the longer term of that sward is going to be productive and high quality.”

Going forward, research work will be carried out in Athenry looking at the performance of multispecies swards under organic farming conditions. Methods of establishing these companion forages other than reseeding will also be evaluated, Dr. Creighton concluded.

For more information on the Growing Organics Programme and Jason Stanley's farm walk, click here.