Tetraploid perennial ryegrasses have higher palatability and can increase per animal and per ha performance.
Tetraploid perennials are not for every situation - they are less robust and require good management for persistence.
Benefits of tetraploids
Tetraploid perennial ryegrasses can be a powerful tool to increase animal production and performance in a range of farming systems. Dairy farmers typically find cows' milk production increases on tetraploid paddocks, and lamb finishers achiever faster LWG. Advantages of tetraploids over diploids include:
- Greater animal preference (or palatability).
- Higher per animal performance can be obtained.
- Easy management (animals graze pastures better).
- High utilisation, driving better per ha production.
- Higher ME and WSC content compared with diploids.
- Open, erect growth habit is clover friendly.
- Advantages of tetraploids are particularly seen in late spring, when their higher palatability drives good post-grazing residuals, which in turn sets up high feed quality for following grazings.
BUT not for everyone
Tetraploids are not suited to all systems. They are more palatable and have a lower tiller density than diploids, so are less robust, and at times need to be better looked after to persist well. Tetraploids are less suited to:
- Wet farms with heavy soils, as they are more susceptible to treading damage.
- Large farms where the owner(s) want every paddock the same to keep the system simple.
- Difficult situations where persistence is the key requirement (a robust diploid cultivar will probably suit best).
- Farms with very high Argentine stem weevil (ASW) damage, as ASW prefer tetraploids.
Getting the best out of tetraploids
At certain times tetraploids need extra care. Their more open growth habit means they are more susceptible to pugging or treading damage by cattle, especially when cows are grazing behind break fences at high stocking rates. Care needs to be taken in these periods.
Through extended dry periods, prolonged set-stocking or repeated grazing should be avoided with all ryegrasses, but particularly with tetraploids as their palatability means they can be grazed to very low covers, affecting their ability to persist.