Adding clovers or herbs to sheep grazed swards

Philip Creighton and Lisa McGrane share details of research work undertaken at Teagasc Athenry, which examined how the addition of clovers or herbs to a sheep grazed sward impact upon animal and sward performance.

In recent years there has been growing interest in the use of diverse sward mixtures for grass based ruminant production systems. Numerous studies have shown the benefits of multispecies swards relative to a perennial ryegrass only swards. These include increased animal and sward performance, reduced requirement for artificial nitrogen application and reduced need for anthelmintic drenches.

Presented below is some of the results from a study in Teagasc Athenry over the last number of years. The aim of this study was to compare a perennial ryegrass sward to binary sward mixtures of perennial ryegrass and one companion forage, in terms of sward and animal performance under an intensive sheep production system. The sward types under investigation were: i) perennial ryegrass (PRG), ii) perennial ryegrass and white clover (PRG+WC), iii) perennial ryegrass and red clover (PRG+RC), iv) perennial ryegrass and plantain (PRG+Plan), and v) 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 (DTS) 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.

Furthermore, reductions in DTS 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 10.7 kg concentrates/lamb drafted for lambs grazing PRG+WC, PRG+RC, PRG+Plan and PRG+Chic respectively relative to PRG which consumed 14.2 kg concentrates/lamb drafted.

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

Average annual herbage production was 11 t DM/ha, and was similar across all sward types. Annual grazed herbage yield was 9.1 t DM/ha and silage herbage yield was 1.9 t 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 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.

Post-grazing sward height

Post-grazing sward height significantly affected all sward types with the exception of PRG+WC. The 4.0 cm PGSH had a negative impact on red clover content, whilst the 5.5 cm PGSH had a negative impact on plantain and chicory contents.

Figure 2: Companion forage content in a year 3 sward (2022) by post-grazing sward height

Seeding rate

Table 1: Seeding rates applied in seeding rate plot trial

Figure 2: Companion forage content by seeding rate

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. Results from these plot trials illustrate that the sward mixtures respond differently to the various management practices. In conclusion, with appropriate management these binary sward types can be successfully incorporated into sheep grazed swards.

The above article was extracted from the Growing Organics Farm Walk Booklet from Joe Nolan’s Farm. Find out more about the Growing Organics Programme here.