Secondary Products from Crops and Animals

Secondary Products from Crops and Animals

Secondary products, also known as by-products, are materials derived from crops or animals that are not primarily consumed for human or animal nutrition. The concept of secondary products, as introduced by anthropologist Andrew Sherratt in the 1980s, reflects a shift in economic practices from the Neolithic era, whereby the exploitation of animals expanded beyond their primary uses to include wool, milk, and traction power.

Today, secondary products play a critical role in enhancing food system efficiency, reducing waste, and mitigating environmental impact. The main secondary products from crops and animals can be categorized as follows:

1. Crop residues: Materials left over after crop harvesting, such as stalks, leaves, and husks.
2. Animal by-products: Materials generated in animal production, such as blood, bone, hide, manure, and offal (e.g., liver, kidney, lungs).

Utilization of Secondary Products

The use of secondary products in animal feed is a key strategy to optimize food system resources and reduce competition for arable land. By utilizing by-products as feed, we can:

1. Reduce competition for arable land: By adding by-products to animal feed, we can reduce pressure on arable land to produce additional feed resources, thus preserving farmland for crop production.
2. Decrease environmental impact: By utilizing by-products, we can lower greenhouse gas emissions, reduce water consumption, and limit the use of fertilizers and pesticides.
3. Boost resource efficiency: By-products are often low-cost materials that can substitute for expensive primary products, such as soybean meal or fishmeal.
4. Increase food system circularity: By repurposing by-products, we can reduce waste and promote a more circular economy.

The Global Picture

The use of secondary products as animal feed differs globally due to regional variations in animal species and production systems. In general, a small proportion of crop residues and livestock by-products are currently used for feed, while nearly all oilseed meals and more than half of crop processing by-products are already used in feed.

The most common by-products used in animal feed are:

1. Crop processing by-products: Sugar beet pulp, cereal bran, and oilseed meals (e.g., rape seed, soybean, sunflower seed).
2. Livestock by-products: Blood meal, hydrolyzed feather meal, meat and bone meal, poultry by-product meal, and poultry oil.
3. Fish by-products: Fishmeal and fish oil.

Challenges and Opportunities

While the use of secondary products has substantial economic, environmental, and social benefits, it is important to consider the potential impacts on other uses of these biomass flows, such as bioenergy, pharmaceuticals, and fertilizer production. The competitive use of by-products for different purposes must be carefully balanced to ensure that food system efficiency is maximized without compromising other essential industries.

In conclusion, the use of secondary products in food systems offers a valuable opportunity to increase resource efficiency, reduce waste, and mitigate environmental impact. However, it is essential to carefully consider the potential impacts on other uses of these biomass flows to ensure a sustainable future for both agriculture and industry.