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If Reused as Animal Feed, Cereal Pulp Could Free Up Millions of Hectares of Farmland

An agricultural field
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Reusing agricultural by-products as animal feed can lead to significant savings in the use of land and water resources, according to a new study.

Published in Nature Food, the study found that by substituting 11–16% of energy-intensive crops currently used as animal feed (cereals, for instance) with by-products from already harvested crops (such as cereal bran), the agricultural sector could save between 15.4–27.8 million hectares of land.

These savings, say the researchers, could become part of the vital global strategy for reducing the unsustainable use of natural resources.

Recycling cereal

Agricultural by-products are defined as secondary products derived from the processing of primary crops such as cereals and sugar. These off-shoots include cereal bran, sugar beet pulp, molasses, distillery residues and citrus pulp.

Animal food products are core to the diets of billions. But animals need food, too, so millions more acres of land are required to grow crops to feed them. This extra demand accounts for almost three-quarters of all global agricultural land.

Animal production can therefore compete with plant food production. 

“Not only does the use of agricultural by-products in animal diets decrease competition between sectors and pressure on resources, but it would also increase the availability of calories that can be directly earmarked for the human diet (e.g., cereals),” said Camilla Govoni, a researcher at Politecnico di Milano.

Govoni and colleagues used an agro-hydrological model combined with crop-specific yield data. They showed that, globally, the agricultural sector could save 15.4–27.8 million hectares of soil, 3–19.6 km3 of irrigation and between 74.2-137.8 km3 of rainwater. This could be achieved by substituting 11–16% of energy-intensive crops (cereals and cassava) currently used for by-products.

“If the saved resources are used for other purposes, including the production of plant foods lacking in current diets, it would improve food security in several countries, with healthier as well as more sustainable food choices,” Govoni added.

Her fellow researcher Maria Cristina Rulli, professor of hydrology at the Politecnico di Milano, concurred: “The use of alternative ingredients in animal diets would lead to increased sustainability and reduced environmental impact not only locally, where the company raises and produces meat and animal products, but also over large distances. Indeed, a decrease in demand for feed could lead to less importation of feed with both economic and socio-environmental benefits. The production of certain feed products actually corresponds to over-pressure on water resources and deforestation, with consequent effects on the concentration of greenhouse gases in the atmosphere, loss of biodiversity and so on.”

Reference: Govoni C, D’Odorico P, Pinotti L, Rulli, MC. Preserving global land and water resources through the replacement of livestock feed crops with agricultural by-products. Nat. Food. 2023. doi: 10.1038/s43016-023-00884-w

This article is a rework of a press release issued by Politecnico di Milano. Material has been edited for length and content.