Samples of imported palm kernel expeller (PKE) have shown higher levels of magnesium, phosphorus, and iron than are recommended for cows, say researchers.
New Zealand brings in around 2 million tonnes of palm kernel expeller every year, mostly as feed for dairy cows.
However, recent testing samples of palm kernel expeller have shown higher levels of magnesium, phosphorus, and iron than are recommended for cows.
University of Canterbury researchers behind the report, Elemental Composition of Palm Kernel Expeller Used as Supplementary Stock Fodder, said it was a complex topic, as the expeller might be a good alternative fertiliser.
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"The chemicals contained in the PKE can significantly affect our soils and animals, both positively and negatively," PhD candidate in environment chemistry at the University of Canterbury, Hadee Thompson-Morrison said.
"PKE may alleviate some micronutrient deficiencies in livestock and provide contaminant-free phosphorus into our soils.
"However, some chemical elements may cause nutrient imbalances in animals, as several elements exceed maximum tolerable levels for animal feed."
Although expeller could be used as a fertiliser, researchers said New Zealand also produced its own biowastes.
They said that, if future research found that our own local biowaste provided similar beneficial nutrients as palm kernel expeller, then it could contribute to a circular economy where waste products were used rather than dumped.
"New Zealand imports approximately 2 million tonnes of palm kernel expeller, a waste product of palm oil processing, from Indonesia per year to support our dairy farms," Thompson-Morrison said. "At current prices, this costs approximately $800 million per year."
Researchers also said palm oil had been linked to the deforestation of virgin tropical forests. They suggested that this, along with the excess elements discovered in their study, warranted a closer look.
"An assessment of the effects of PKE on the sustainability of our agricultural systems is urgently needed," Thompson-Morrison said.
