- With more research, microalgae have the potential to change the sustainability of animal and food production systems.
- Their rapid growth and nutritional content may be valuable for use in swine diets in the future.
- Microalgae could be an alternative feed ingredient that helps support growing populations.
Why use microalgae in animal feeds?
- A long-term agricultural challenge is achieving sustainability.
- Microalgae could become a key feed ingredient, which can serve as a major raw material for biofuel production and a nutrient source for animal feed.
- Use of microalgae in animal systems could potentially lower the carbon footprint in animal production by limiting the land needed for corn and soybean production.
- Various chemicals and functional nutrients present in microalgae make it a potential alternative to growth promoting antibiotics in animal feeds.
What are microalgae?
- Microalgae are microscopic algae.
- Algae are a class of organisms that live in water and convert sunlight to energy.
- Algae are more efficient than plants at this process and some can double their biomass in a few hours.
- This makes algae nature’s most efficient primary producers, and they account for more than 50 percent of global carbon fixation (carbon dioxide to organic compounds).
There are thousands of different species of microalgae, which vary in nutritional composition. Examples of common microalgae species include
- Bacillariophyceae (part of phytoplankton)
- Clorophyseae (green algae)
- Cyanophyceae (blue green algae)
- Chrysophyceae (golden algae)
Algae have the potential to increase the quality of animal feed by acting as a nutritional supplement that is high in desirable protein and other nutrients. However, further research of algae as a supplement in swine diets is needed as different algal strains have different nutritional characteristics.
Harvesting and processing
Microalgae come from a variety of places including:
- Freshwater environments
- Many are processed using fermentation tanks, which produce a lot of microalgae in a small amount of time
- These microalgae species don’t require fermentation and can simply be taken from wastewater
- Biofuel production systems
- Defatted microalgae come from these systems. Defatting refers to the process of removing fat from the microalgae.
Nutritional potential in swine diets
Microalgae are useful and attractive as a feed supplement for livestock diets.
Several forms of microalgae were evaluated as feed supplements. These microalgae had crude protein (CP) levels ranging from 14 to 38.2 percent. At 38.2 percent CP, microalgae contain almost 4.5 times the amount of CP in different corn products.
Microalgae products are also high in the following.
- Fat content, which ranges from 1.5 to 9.3 percent
- Beneficial omega-3 fatty acids
- Other bioactive compounds
University of Minnesota mice models have shown that the nutrient content of microalgae can lead to changes in metabolism. These changes suggest that feeding pigs microalgae may help increase antioxidant defense and growth.
Some microalgae contain sugars (beta-glucans) that are beneficial to the pig’s gut, especially immature pigs, as their guts are still developing. Gut development is extremely important to the overall health and growth of the animal.
Experiments suggest that microalgae use in animal diets is promising. However, we need more information before widespread use of microalgae occurs in animal feeding programs.
Further research should look at:
- Bioavailability of the nutrients: How available are the nutrients to pigs after eating the microalgae?
- Digestibility: Are microalgae easy for the pig to digest?
- Potential toxin levels: Is there enough toxin present to harm the pig?
These aspects of feeding microalgae are key to accurately formulating diets for growing pigs.
The table below shows the general nutritional characteristics of a few species of microalgae.
|Species||Harvest processing method||Crude protein (% dry matter)||Carbohydrates (% dry matter)||Lipids (% dry matter)|
|Anabaena cylindrica||Freshwater biomass, dried||43 – 56||25 – 30||4 – 7|
|Spirulina maxima||Cyanobacterium, single cultivation||60 – 71||13 – 16||6 – 7|
|Chlorella vulgaris||Wastewater collection, dried or oil extraction||51 – 58||12 – 17||14 – 22|
|Staurosira sp.||Defatted biomass, biofuel co-product||19||14 – 15||3 – 4|
|Crypthecodinium sp.||Glucose/acetic acid cultured, dried, oil extraction||12 – 15||40||40 – 50|
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Reviewed in 2019