Willow and poplars offer valuable feed source
As dry conditions and feed shortages hit many parts of the country, the Poplar and Willow Research Trust has reminded the farmers that their poplars and willows offer a valuable feed source.
Known for their erosion control and shade qualities, palatable poplars and willows should also form part of a farm drought resilience plan.
“In summer, often the only sight of green on parched farms is trees,” said Trust chairman Bruce Wills.
“Poplars and willows are deep rooting and draw moisture in times of drought providing nutritious feed when pasture has died off; many farmers already use them as an extra on-farm fodder supply and our website has fact sheets and how-to videos to help others do it too.”
Both poplars and willows have proven resilient and respond well to removal of branches by growing more.
This pruning system is known as pollarding, with the upper branches of a tree cut back to a stump above cattle grazing height, promoting a dense head of foliage and branches.
Cattle will eat trimmings up to 10mm and sheep up to 5mm in diameter.
“The feed value is well above stock maintenance requirements,” Mr Wills said.
“The feed value of poplar and willows leaves is 65–70 percent dry matter digestibility, about the same as lucerne hay.
“A crude protein level of 15 percent is well above that required for livestock maintenance.
“The leaves contain valuable compounds called condensed tannins (CT) and phenolic glycosides (like aspirin) and these have health benefits for stock.
“Massey University research found five to 10-year-old trees yield up to 22kg dry matter per tree of edible forage, and that poplars and willows were similar in nutritive value.
“Condensed tannin levels are usually higher in willows. Willow leaves are also high in zinc and magnesium, which are important animal health minerals.
“However, sodium (salt) levels can be low in willow leaves, and, if little or no pasture is on offer, a salt block should be provided.”
The tree bark also has good nutritive value.
“Both cattle and sheep will strip off and eat the bark; it takes just one feeding to condition stock to eating tree fodder in drought.”
Research trials by Massey University showed improved lambing percentage for stock fed on poplar and willow forage compared with stock fed on drought pasture alone.
Mature poplars and willows shed a large quantity of leaves in autumn and early winter. Once trees are about five years of age, leaf fall can provide 60kg or more of dry matter per tree.
Pollarded trees regrow as bushy trees bearing plenty of fine stems for feeding — but out of stock reach.
After the initial pollarding it is relatively easy and much safer to cut off these thinner branches when growing at this height. “These trees will still act as water pumps, helping to prevent erosion on unstable hill slopes,” Mr Wills said
“Soil conservation trees intended for pollarding should be planted six to 10 metres apart and not pollarded for at least five years, but thereafter can be harvested on a three to four-year harvesting cycle.”