Elemental Composition of Palm Kernel Expeller Used as Supplementary Stock Fodder

Palm kernel expeller (PKE) is a biowaste by-product of palm oil processing in Southeast Asia that is exported as stock fodder. Global production of PKE totals 11M t yr(-1), of which New Zealand imports 1.9M t yr(-1), worth >USD 325M, most of which supports NZ's dairy herd of 5.5M cows. We aimed to determine the concentrations of the chemical elements in PKE imported into New Zealand and compare this to pasture, as well as to assess chemical concentrations against maximum tolerable levels (MTLs) in stockfeed for animal health and ruminant requirements. Palm kernel expeller was analysed for a suite of essential and trace elements using a HNO3 digestion and analysis by inductively coupled plasma-mass spectrometry. Palm kernel expeller contained statistically significantly higher concentrations of B, Mg, P, Cr, Mn, Fe, Ni, Cu and Zn than pasture. Magnesium, P and Fe exceeded MTLs in PKE, whereas Al, S, K and Cu were within 90% of their MTL. The N, P and K contained in PKE represent the equivalent of 14%, 20% and 28%, respectively, of dairy fertiliser use in New Zealand. As PKE contained 3.3 mg Cd kg P-1, there may be potential for PKE to offset fertiliser use in dairy systems, with a low Cd source of P. There were statistically significant differences in elemental concentrations between different batches of PKE indicating that this product is not uniform. Further research of the effects of PKE on animal health is recommended. The excess elements contained in PKE may present risks or benefits to dairy farming systems and determining these would be beneficial in protecting both animal health and environmental sustainability.

Automated summary

This study investigated the concentrations of chemical elements in palm kernel expeller (PKE) imported into New Zealand and compared them to pasture. The results showed that PKE had higher concentrations of certain elements compared to pasture, and some of these elements exceeded the maximum tolerable levels for animal feed. The study also suggested that PKE could be used as an alternative to fertilizers in dairy systems due to its low cadmium content.