Animal feed plays a major role in the environmental impact of your diet. In dairy and beef production, it accounts for about 36 and 55 percent of greenhouse gas (GHG) emissions, respectively. The raw materials for animal feed typically consist of crops like soybean and wheat and animal-based products like fish meal and fish oil. But the production of these ingredients could be detrimental to the environment.
About 33 percent of croplands are dedicated to livestock feed production, which may result in nutrient and pesticide runoff. Crops for animal feed also make up about six percent of the GHG emissions from global food production. Meanwhile, increasing demand for feed made from marine byproducts may be unsustainable for ocean ecosystems.
“When we feed these ingredients to animals that have their own environmental impact from production, the overall impact is much higher than if we just ate the ingredients themselves, “ says Caitlin D. Kuempel, conservation scientist and lecturer at the Griffith University School of Environment and Science in Australia. “The more feed required to grow an animal, the higher this overall pressure can become.”
Global food production, including plant and animal agriculture, is estimated to make up 26 percent of the total GHG emissions around the world. Therefore, to reduce the environmental impact of animal products, it may be beneficial to look at their diets and work on making them more sustainable as well.
For many types of farmed animals, feed typically accounts for 50 to 70 percent of production costs, says Kurt A. Rosentrater, food engineer and associate professor at Iowa State University whose research focuses on improving the sustainability of agricultural-based systems.
“Ironically, the production of feed and the ingredients that go into these feeds can often result in up to about 70 percent of the environmental impacts from eating products from these animals,” says Rosentrater. That’s not the case for all species, especially since ruminants produce significant GHG emissions during digestion. But for most animal-based products, the most significant portion of environmental impacts happen on the farm before they are even processed into food products, he adds.
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For instance, animal feed given to farmed broiler chickens and farmed salmonids (including salmon, marine trout, and Arctic char) account for more than half of their respective industries’ environmental impact, according to a recent Current Biology study. Feed production accounts for at least 78 percent of the environmental pressures of farmed chicken, and over 67 percent for that of salmon.
Chicken and salmon are the largest animal-sourced food sectors on land and the sea, which makes them a fitting focus for research. “We combined data on four pressures—greenhouse gas emissions, freshwater use, nutrient pollution, and land and sea disturbance—into a single metric to get a more holistic view of the environmental footprint of these two production systems,” says Kuempel, who was involved in the study.
The findings revealed that 95 percent of the environmental footprints of chicken and salmon are concentrated in just five percent of the world, which includes some of the largest producers like the US and Chile. Knowing the spatial distribution helps give more local context. This could help identify areas that may have resource competition, and focus on location-specific policies to reduce environmental impact, says Kuempel.
Moreover, the study found that more than 85 percent of farmed chicken and salmon’s environmental footprints overlap primarily due to their shared feed ingredients. Commercial poultry feed often consists of crops like corn and wheat, but they also contain fish meal and fish oils. At the same time, salmon aquaculture requires 2.5 million tons of crops like soybean and wheat for feed, but they still eat fish meal.
“Since feed contributes such a high percentage of their environmental footprint, this is an obvious area where changes could potentially be made to lower their environmental pressures overall,” says Kuempel.
Some actions can improve the sustainability of feed production, including changing the dietary composition of feed ingredients to include more environmentally friendly options, says Kuempel. This can be effective since the environmental impacts of feeds are primarily influenced by their ingredients.
In a 2021 study, the authors found that reducing the proportion of high-impact ingredients, like cereals and oils, while increasing the proportion of low-impact ones, like peas or fava beans, may result in eco-friendlier pig production without harming animal performance.
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The fast-growing aquaculture industry has also influenced a shift to crop-based feed ingredients to maintain sustainability in ocean ecosystems. However, for carnivorous farmed fish, plant-based diets would affect their nutritional profile, and subsequently, human nutrition. More studies are needed to understand the impact of different feed formulations on various farmed fish.
A 2020 Scientific Reports study found that reducing the fish meal component from 35 to 15 percent in the feed for the Atlantic salmon parr reduced their growth. However, partially replacing it with fish protein hydrolysate (FPH) supplementation in a high plant protein diet might result in a similar growth performance with the fish fed with a 35 percent fish meal.
Kuempel also suggests introducing novel feeds like microalgae and insects to potentially reduce environmental pressure. Microalgae could successfully replace fish meal and fish oil in aquaculture diets while also improving growth and meat quality in poultry and pigs. Feeding trials conducted on chickens, several fish species, and pigs concluded that insect meal could replace over 25 percent of soy meal or fish meal in animal feed with no adverse effects.
Overall, animal feed production has the capacity to become more sustainable. “Many researchers are hard at work trying to improve the efficiency of ingredient growth and processing, as well as improved digestibility and reduced GHG emissions during digestion,” says Rosentrater. “Many promising developments are underway that will soon reduce the impacts of feed and ingredient production, processing, and digestion.”