Duckweed (Lemna minor) as an alternative and sustainable feed source for a resilient livestock production system

Background

Ruminants, such as dairy cows, are a crucial part of food security by efficiently converting grass into valuable protein in milk and meat. While the diet of dairy cows primarily consists of grass silage, it also includes cereals and protein feeds such as soybean and rapeseed. However, climate change introduces extreme weather events that could disrupt crop harvests.

Thus, this project aims to explore an alternative feed source. Duckweed (Lemna minor), a common aquatic plant in Sweden, grows rapidly and tolerates varying water temperatures. Its high protein content makes it a potential substitute for soybean and rapeseed. Furthermore, its cultivation doesn't rely on arable land and is less susceptible to extreme weather conditions. Duckweed's ability to absorb nutrients from field runoff, manure, and greywater has the potential to promote circular economy practices at the farm level and reduce the environmental impact of ruminant-based food production systems.

Project activities

Initially, duckweed will be gathered from diverse growing environments throughout Sweden, as well as be cultivated using wastewater from a dairy plant and manure from a dairy farm. A lab study will examine how various growth conditions impact protein quality and digestibility for ruminants. Subsequently, another lab trial will assess duckweed's suitability as part of a standard diet for dairy cows.

Finally, two feeding trials with dairy cows will investigate how replacing soybean and rapeseed meal affects feed intake, milk production, milk quality, animal health, and emissions of ammonia and methane. The feeding trials will be conducted at the Röbäcksdalen dairy research barn at SLU Umeå.

Project manager:

Petra Fant, petra.fant@slu.se

Collaborators:

Björn Oliviusson, Svensk Aquaponik, Stockholm

Alexander N. Hristov, Penn State College of Agricultural Sciences, Pennsylvania, USA