Continuing on from looking at native fodder trees and plants, we look at suitable exotic trees and plants to grow for livestock fodder.
Willows and poplars are already established on many New Zealand farms for erosion control and shelter but they can also provide valuable fodder for livestock. Fast-growing and with a quick recovery rate after grazing, they are nutritious and highly palatable. Willows produce more fodder than poplars but poplars produce higher-value timber.
There is plenty of information available about planting, managing and using poplars and willows in New Zealand (see under “References”). However, there are other trees and plants that are also suitable for producing fodder but which may not be recognised as such. Some of them are listed below.
1. Tagasaste, tree lucerne (Chamaecytisus palmensis)
The darling of the permaculture movement because of its multi-purpose nature, this nitrogen-fixing legume is native to the Canary Islands. It can be fed to sheep, cattle, pigs, horses and rabbits. Chickens love the seeds and leaves. As the plant flowers in winter, it is also a useful fodder plant for bees.
Tagasaste has high nutrition levels with low toxicity and is very palatable. Grown under the right conditions, it can exceed both lucerne and rye grass in protein, carbohydrates and crude fat.
The shrub is fast-growing, can survive on a wide range of soils and, with sufficient phosphorus, will tolerate drought. Tagasaste grows to 7m and is fairly short lived, but cutting or browsing can extend this. Although it is considered frost-hardy to minus 9degC, young leaves will die off, particularly if the plant has been heavily grazed just before winter. Severe frosts will kill the entire plant.
2. Honey Locust (Gleditsia triacanthos)
Honey locust is a legume but opinion is divided on its nitrogen-fixing abilities. This fast-growing but comparatively short-lived (120 years on average) native of North America can reach 30m in height with a trunk diameter of 60-90cm. The tree is very thorny but thornless cultivars are available.
In autumn, honey locust produces long pods which are very palatable to sheep, cattle, horses, pigs and goats. The pods are high in carbohydrates (85%) and protein (12-24%), and are said to be nutritionally superior to oats. Sheep and goats digest the entire pods but cattle and horses excrete the seeds.
Honey locust is deciduous and needs 425-1500mm of rain for good growth. It will tolerate any deep soil — acid, alkaline and mildly saline – and can withstand drought when established. It coppices easily and is frost-resistant when mature.
Honey locust’s spreading nature provides dappled shade and allows pasture growth up to the trunk. However, this also makes branches prone to snapping off in high winds.
3. Linden, Small-leaved Lime (Tilia cordata)
This shade-tolerant, cold and frost-hardy tree is native to the UK and Europe. A medium-to-fast grower, it can reach over 30m in height, with a spread of 12-22m. Lindens can live in excess of 1,000 years, longer if coppiced.
Linden leaves are relished by sheep, goats, deer and cattle. Traditionally, the trees were pollarded (top-cut every 2-6 years to produce lots of bushy new growth) to produce stock feed. The dried, leafy branches were known as “pollard hay”.
Linden likes medium to rich fertility and well-drained soil with a neutral-to-alkaline pH. It won’t do well on very dry or nutrient-poor sites and it can be prone to aphids, phytopthora and verticillum wilt.
4. Mulberry (Morus spp.)
Deciduous and dome-shaped, the mulberry tree grows to 20m. It is a long-lived and hardy tree and is usually self-fertile. The best-known forms of mulberry are the white (M. alba, native to east Asia and the traditional silkworm mulberry), the black (M. nigra, native to southwest Asia) and the red (M. rubra, native to eastern North America). The black and red varieties produce the tastiest fruit.
Mulberry leaves are relished by sheep and cattle and are said to increase milk yield in cows. The leaves have high digestibility (70%), with a protein content of 18-22%. They are a rich source of carbohydrates and phosphorus (0.4%). Feed value is considered superior to lucerne and it’s been claimed that up to 60% of a ruminant diet can consist of mulberry. The fruits are good for poultry and pigs.
Mulberry can be grown from seed or cuttings. It will grow in full sun but is also shade-tolerant and coppices well. Depending on cultivar, the tree can take up to 10 years to start fruiting. The white mulberry is the fastest grower and can tolerate more humidity than other varieties.
5. Tree Medick, Moon Trefoil, Shrub Medick (Medicago aroborea)
Tree medick hails from the same family as lucerne and, like lucerne, is a nitrogen-fixing legume. Perennial, woody and evergreen, this shrub grows to 4m. It originated in the Mediterranean region and is found throughout Europe.
Sheep, goats and cattle will readily browse on tree medick. The feed quality is equivalent to lucerne, with high protein and digestibility and low crude fibre content. However, production is lower than lucerne.
Tree medick originated in coastal areas and is tolerant of wind and salt spray. It can survive drought and will grow on most soils. There are reports of this plant surviving frosts to minus 10degC if grown against a wall but it’s generally accepted that tree medick is vulnerable to hard and/or sustained frost and this has probably limited its range and usefulness in New Zealand.
6. Saltbush (Atriplex spp.)
A drought-resistant, woody shrub found in many arid areas of the world, saltbush is tolerant of salt and high pH. It is fast-growing, capable of reaching maturity in two to three years. Height ranges from 0.25m to over 2m.
Saltbush is generally fed out to sheep in late summer and autumn. Cattle can browse the bushes if they grow too high for sheep to reach but excellent palatability means this should be controlled. The shrubs are productive and nutritionally comparable with lucerne, with crude protein constituting 15-25% of dry matter for leaves and twigs. Leaves are also high in Vitamin E. As saltbush has a high salt content, browsing stock should have access to fresh drinking water at all times.
Saltbush is quick to establish from seedlings and rooted cuttings. It grows best in soils with a pH of 7.0 to 8.5 and does not tolerate soil aluminium. It can flourish in highly fertile soils as well as those with lower nutrient levels. Mediterranean saltbush is frost-hardy to minus 10degC, provided it still has plenty of leaf cover going into winter. Old man saltbush shouldn’t be planted in frosty regions.
Pest potential of fodder trees and shrubs
The very qualities that make certain trees and shrubs so desirable as fodder plants – fast-growing, vigorous, easy to establish, tough as old boots – can also cause problems if not properly managed. Fodder trees/shrubs need to be maintained and grazed on a strict rotation. Some, like tagasaste, are colonisers and have the potential to become weedy. (Acacias and bamboo were not included in this feature for that reason.) Others, like poplar and willow, can be dangerous to prune if neglected and allowed to grow too large.
