Kikuyu is an aggressive plant and will establish in thick mats preventing other plants from growing. Kikuyu is very active in the summer and autumn with high pasture growth rates, and it is tolerant to dry conditions. Kikuyu grows substantially less than ryegrass through the winter and spring periods due to the cooler temperatures. It is susceptible to frost damage and this can result in negative growth rates
Kikuyu Leaves are mostly hairless, with slightly rough margins and the top section of the midrib.
The kikuyu seedling produces leaves from the crown. New leaves are produced from nodes on the primary and secondary tillers
The Rhizome is a underground stem which forms nodes and extends. The tip or the rooted nodes can produce leaf if exposed to light by coming up through the soil surface.
The Stolon is a tiller which becomes long and scrambling. Stolon’s typically have 5-10 live leaves at the growing end and further from the tip dead leaves or leaf bases at each node.
Seed head or flower spikelets are hidden in leaf sheaths of the vegetative side shoots. While the grass spreads well via vegetative reproduction from pieces of rhizome, it is also dispersed via seed.
Leaf stage and quality
After grazing each new leaf grows up to 4 new leaves before the oldest leaf begins to die.
After 4 leaves have grown the stem growth increases substantially, and the amount of green leaf reduces. This results in a dramatic decline in the quality of kikuyu.
Grazing needs to occur at the 4-4.5 leaf stage to provide the highest proportion of leaf and the higher quality pasture for the herd.
Grazing later than this not only lowers pasture quality but also will reduce the annual yield of leaf DM produced.
- Best milk production is from fast-growing green leaf (10-11 ME/kgDM).
- Stem/stolon can be milked off only when it is green and growing (9-10 ME).
- Quality declines rapidly in the stem/stolon after two to three weeks of growth (8-9 ME). When kikuyu is on a long rotation the feed quality of the stolon is as low as 7 ME.
Leaf emergence and grazing interval
Leaf emergence rate depends primarily on temperature. From December to March a new leaf emerges every 3-4 days. Moisture stress can slow leaf emergence.
In wetter summers grazing intervals of every 12-14 days (4 leaves x 3 days/leaf) are appropriate for kikuyu pastures from January to March if both pasture quality and annual yield are to be sustained. In dry summers grazing interval for kikuyu may need to be 18-20 days.
Kikuyu over 4 weeks of age is ‘old’ - especially when kikuyu is growing rapidly. By 6 weeks the leaf will be just 9 to 10 ME which is barely productive for milk or growth. By this time the stem is around 8 ME and cattle will only eat the leaf. In early summer (e.g. December and January kikuyu produces a high ratio of leaf to stem/stolon (70:30). This ratio declines during the season and can be as low as (30:70) in autumn
From April, the grazing interval for kikuyu pastures needs to be lengthened to transition from kikuyu dominant pasture to ryegrass dominant pasture.
1) Fast rotations (~18-20 days) when kikuyu is still dominant in the pasture and growing rapidly
2) Longer rotation lengths more typical for ryegrass pastures (30-60 days) as ryegrass becomes dominant in the pasture (e.g. 30-40 days in April, 50 days in May and >60 days in June).
Grazing residuals for kikuyu
A grazing residual height of 5-8cm is recommended for kikuyu. Regular grazing to 5cm and grazing at the 4 to 4.5 leaf stage helps prevent a build- up of stem over time.
After several rotations mowing or mulching to a height of 2.5 to 5 cm may be required, or use non-lactating animals to graze back below 5 cm.
Measurements of annual DM yield in Northland show Kikuyu and Ryegrass have similar annual yields but big variations between and within years. Pastures containing both Ryegrass and Kikuyu generally out yield those containing either species on its own, by 5-6%.
Measurements from the NARF showed very similar total annual production over a three-year period.
Annual Pasture Growth Rate (Kg DM/ha/year) from the farmlets.
Average 3 years
Annual Pasture Growth (t)
While Kikuyu has a similar total annual growth to Ryegrass pastures, its seasonal production is very different due to it being a sub-tropical grass preferring warmer conditions.
Winter Spring Yield
Research measurements of winter pasture growth rate shows kikuyu grows less than ryegrass in winter (-15% to -20%) and spring (-8% to -25%). Pastures that remain Kikuyu dominant in winter may grow as little as 0-10 kg DM/ha/day compared to ryegrass which will grow 15-25 kg DM/ha/day under the same conditions.
Pastures that remain Kikuyu dominant in winter are susceptible to frost damage. The Kikuyu leaf will very quickly be turned into a brown rotting mass of dead leaves following the frost. If it rots it may be replaced by undesirable species
On farm measurements at Jagger’s dairy farm at Whangarei Heads show the extent of the difference in pasture growth rates in both winter and spring between kikuyu and ryegrass pastures.
Kikuyu summer growth will exceed ryegrass from December to June north of Kaitaia, and from January to May in coastal areas further south. Through summer Kikuyu is able to achieve high summer growth rates of 80 to 150 kg DM/ha/day. Kikuyu must be managed well to optimise pasture quality through this period of the year. Kikuyu autumn growth can be variable depending on weather conditions. In general, the growth of Kikuyu pastures will out yield Ryegrass pastures under warm, dry conditions.
Animal health and performance
Where kikuyu has not been well managed quality issues can occur:
- Winter kikuyu is low ME, especially following frost damage and will not be sufficient for body condition score gain.
- Feed quality can decline rapidly when grazing interval is not managed. Kikuyu declines in quality as it accumulates more dry matter. The faster it grows the quicker it loses quality. When cows are used to control poorly managed kikuyu, cow performance can be affected. Old stolon (occurs if paddocks are not mulched or mown) is only 7 MJME and has poor digestibility.
- Stolon impaction of the rumen of cows can occur in late autumn, winter, or spring, usually in non-lactating but pregnant dairy cattle that are fed large quantities of kikuyu pasture with high stolon content. The cattle lose condition as the nutritive value of the pasture is low, and because they are incapable of sufficient intake of the indigestible kikuyu dry matter. The stolon fibre also has a rate of throughput which is too slow to meet the demand of advancing pregnancy.
- There have been reports of kikuyu toxicity particularly after army worm infestation. These events are rare.
- These can be important issues when grazing dry cows off-farm for winter on saved kikuyu. It’s important to visit the grazing block with the grazier and discuss how they will manage the risks of poor quality feed and low pasture growth in winter.
Kikuyu transports very little sodium (Na) to its leaves. Cows need direct supplementation with sodium (salt licks)
- Species composition influences the Na content of pasture. Kikuyu transports very little Na to its leaves, restricting it mainly to the roots and lower stems. Kikuyu is incapable of providing enough sodium for grazing animals even when the soil in which they grow is not deficient or when fertilisers containing sodium have been applied. In contrast, ryegrass and white clover readily absorbs sodium and transports it into their leaves, where it is consumed by cows
- The coastal situation of some New Zealand farms means that salt-laden air supplies sufficient Na to meet the daily requirements. However, in inland areas Na deficiencies can arise.
- High application rates of potassium fertilisers can also depress herbage Na levels.
Deficiencies - reports indicate that specific nutrients may be limiting
- Trace element deficiencies could also be an issue on some farms. However, similar nutritional limitations also apply to all other pasture species and may be altered by seasonal factors or by management such as stocking or fertiliser rates.
- Low phosphorus levels can result in deficiencies slowing livestock growth.
- Low magnesium increases the risk of metabolic disease (e.g. milk fever) in the dry cow.
- Research shows that trace element deficiencies are unlikely to limiting livestock performance on Northland farms. Trace element nutrition is complex and supplementation should be discussed with your vet.
- When properly managed, kikuyu adds to pasture productivity in January and February and are the highest producing summer pastures in Northland.
- Kikuyu is more drought tolerant than ryegrass and pastures recover quickly following summer rain
- Well manged kikuyu (green leaf) is 10-11 ME. Leafy kikuyu provides good summer feed for growing young stock
- Kikuyu pasture has a lower risk facial eczema risk than ryegrass.
- Kikuyu does not get rust so doesn’t face the same palatability issues as ryegrass
- Less bloat, and no risk of ryegrass staggers