It’s green, the cows eat it and it grows when it’s got sunlight, water and warmth… what more do I need to know about choosing a grass type for my farm?
Should I choose a short rotation or a perennial? Are more four chromosomes better than two? What actually is endophyte? Are there tools that can help me assess which cultivar is the best fit for my needs?
What are you going to plant?
Are you looking for a ryegrass-based pasture, or are you considering other grass species such as cocksfoot, tall fescue (or fescue hybrids)?
Ryegrass is the most commonly pasture grass sown in New Zealand dairy farms. Ryegrass types can be categorized into four main categories based on their persistency and retention in pastures. Annual (less than one year) and Italian (1-2 year) ryegrasses are typically used for their ability to establish quickly and provide good winter and early spring dry matter accumulation and are often used as part of a cropping pasture renewal program. They are not typically put into permanent pasture mix, as when they die out they can leave opportunity for weeds to get themselves well established.
Hybrid/short rotation ryegrasses typically last 2-5 years and are generally a cross between a perennial and an Italian type ryegrass. They will generally grow similar yields as perennial ryegrass across a year but have higher winter growth. They are often used in situations where the paddock is only wanted as short-term pasture or stitched into thinning pastures or added to permanent pasture mixes to improve winter production in the first few years after establishment.
Perennial ryegrasses are a more permanent pasture grass, with expected life of over 5 years. These grasses have good persistence, particularly under good management in areas that are summer moist (or under irrigation).
Cocksfoot is a very persistent grass, with good tolerance in dry conditions, but typically it has lower feed values than ryegrasses. Tall fescue can be a good alternative in areas where ryegrass persistence is a challenge or summer growth is a challenge. Companion species commonly used in New Zealand pastures are white clover and grazing herbs, such as plantain and chicory. These help improve feed value and palatability.
What about the ploidy?
The difference between a diploid (2n) and tetraploid (4n) ryegrass is something that is often confused, and I have even been told in the past that the difference is just the number of “N’s”. The ploidy of the plant refers to the number of chromosomes that the plant has – a diploid plant has two sets, while a tetraploid plant has four sets. In real terms this means that the diploid plant have more tillers per plant and a higher DM%. They are a more robust plant, and are more tolerant to pugging. However, they can be less supportive to clover growth due to their dense, low growth habits. Tetraploid grasses have a bigger cell size and therefore a higher ratio of soluble carbohydrates to fibre. They typically have a higher ME and palatability, but are more prone to overgrazing, pugging damage and require careful management through both wet and dry periods.
Does the choice of endophyte matter?
Endophyte is fungus found in the seed of the ryegrass and tall fescue plant, which due to its growth habits will be found in high concentrations in the base of the plant, and in new seeds grown during the plants reproductive phase. This endophyte provide protection to the plant against pasture pests, but the “wild” types also have negative animal health effects, especially as a cause of ryegrass staggers. Novel endophytes can be inoculated into the seed to provide protection against pasture pests, while removing or minimizing the harmful toxins. The choice of what endophte to use will depend on the pest challenges in the area, with different endophytes providing protection against Argentine Stem Weevil, black beetle, pasture mealy bug, porina and some even working towards grass grub protection.
The heading date of ryegrasses is always set relative to Nui, which was approximately the 22nd of October. The heading date is defines as the date at which half of the grass plants have emerged seed heads. Early heading grasses will have better early spring growth, whilst later heading grasses will have better feed quality in the late spring and summer. A couple of important rules to note are to not sow more than 50% of the farm in late/very late heading grasses as you may cause early feed pinches. It is a good idea to have a mix of heading dates across the farm, but not within the same paddocks. By mixing heading dates in a paddock you reduce the impact of improved late spring feed quality of the later heading cultivars, but also make it more difficult to manage seed head emergence.
Using the Forage value index and cultivar selector tools
The forage value index tool is a profit-based index for ryegrasses that is region specific and independent of the seed companies – its kind of like cows breeding worth, but for grass! It combines trial data, allocates performance values and the corresponding economic values to each trait of the cultivar, then gives an indication of which grass would be most appropriate for your needs. The information from the FVI feeds into the cultivar selector tool which can be found on the DairyNZ website https://www.dairynz.co.nz/…/select…/cultivar-selector-tool/…
Any more questions on making the best choices for your farm, farming system and fitting with your feed budgets? Get in touch with one of our team to discuss.