Microalgae have potential as a fish feed ingredient. Research is evaluating the nutritional value and functional properties of different microalgae species. Preliminary results found that Nannochloropsis oceania, Phaeodactylum tricornutum, and Isochrysis galbana vary in their protein, lipid, and amino acid content. Feeding microalgae may help reduce soybean meal-induced inflammation in salmon intestines. Further research is needed to improve the digestibility and cost-effectiveness of producing microalgae at commercial scales for use as sustainable fish feed ingredients.

1. Microalgae – a potential fish feed
resource?
Margareth Øverland

2. Salmonid production, Norwegian and global

3. Potentials and challenges with
plant ingredients
3

4. Fishmeal-free diets for salmonids
Pea1.0 IX
+ potato
A: P-M
Mixed model design
2
Contour plot Feeding a combination of pea, potato and
rapeseed protein gave similar growth
performance as fishmeal
0.780
0.788
2 2
0.0 0.0
0.799
2
0.832
0.850
0.817
0.832
0.850
2 2 2
Source: APC, Zhang, 2012
1.0 0.0 1.0
B: C-M
Rapeseed
IX
Soya
C: S-MIX
+Potato
Feed efficiency
FCR

5. Microbial ingredients in fish feeds
Production
Yeast/Fungus Microalgae
Bacteria Phaeodactylum, Chlorella,
Methylococcus capsulatus Rhizopus oryzae
Many possible substrates:
• Methane or methanol (e.g. natural gas or methane)
• Co-products from forest industry and agriculture
- Lignocellulosic biomass
• Sunlight + CO2

6. Bacterial meal
Value chain from natural gas to high-value feed resources
for
the production of human food
Methylococcus capsulatus
Crude protein (10% nucleic acids) 70%
Crude lipids (phospholipids) 10%
Carbohydrates 12%
Ash 7%
(Source: Øverland et al., 2011)
Bacterial meal (BM) is produced by aerobe fermentation:
• Methanothroph bacteria and helper bacteria
• Methanol or Methane from natural gas
• Oxygen, ammonia, minerals

7. Growth (%/Day) and feed efficiency (Gain/Feed) of
Atlantic salmon fed increasing levels of bacterial
meal
b
b
c
ab
bc
abc
ab
a a a
Level of bacterial meal (%)
Source: Aas et al. 2006

8. Production of yeast from forest industry
Lignocellulosic biomass
Cellulose

9. Growth (%/day) and feed utilization
(feed:gain) of salmon fed 30% yeast
a
Gain, %/day
Kg feed / kg gain
FM Yeast 1 Yeast 2 Yeast 3
APC, 2012, Øverland et al., unpublished

10. Microalgae in fish feed
Chemical characteristic of microalgae
Microalgae
Phaeodactylum, Chlorella
Crude protein 20 - 40%
Crude lipids 5 - 60%
Carbohydrates
Minerals, vitamins, carotenoids
Microalgae is produced by:
• Heterotrophic or autotrophic production
• Freshwater or saltwater
• Lipid, protein and carbohydrate composition varies with production
conditions

11. Reseach on Microalgae in APC
1. Evaluation of nutritional value of :
Nannochloropsis oceania, produced at UMB
Isochtysis galbana from, Reed Mariculture, USA
Phaeodactylum tricornutum, Fitoplankton Marino, Spain
Collaboration among APC; UMB, SINTEF, and Nofima
2. Evaluation of functional properties of
microalgae
3. Chemical profiling of microalga from
heterotrophic production Production of Nannochloropsis
Collaboration between APC and Nofima oceania at UMB

12. Chemical composition of microalgae, %
Nannochloropsis Isochrysis Phaeodactylum High-quality
Oceania galbana tricornutum fishmeal
Crude protein, % 47.7 20.1 49.0 74.7
Crude fat, % 8.4 16.2 7.4 9.7
EPA, C20:5 2.3 0.08 2.8 1.5-2.0
DHA, C22:6 - 1.6 0.02 0.7-1.3
Amino acids, g/16 g N
Lysine 4.8 3.1 4.2 6.8
Methionine 1.8 2.5 2.0 2.5
Tryptophan 1.7 2.5 1.3 0.7
Threonine 3.6 4.6 3.7 3.5
Valine 4.6 6.1 4.6 4.0
Isoleucine 3.5 5.1 3.8 3.7
Leucine 6.7 9.2 6.2 6.2
Phenylalanine 3.9 5.7 4.2 3.3
Source: APC, Skrede et al., unpublished
Arginine 4.9 4.1 4.4 5.4

13. Apparent crude protein digestibility of the
algae products
Nannochloropsis Phaeodactylum tricornutum Isochrysis galbana
100 100 100
90 90 90
80 80 80
70 70 70
% CP digested
% CP digested
% CP digested
60 60 60
50 50 50
40 40 40
30 30 30
20 20 20
y = -0,5233x + 87,844
y = -0,0777x + 87,639 y = -0,69x + 87,806
10 R2 = 0,9966 10 R2 = 0,9853 10 R2 = 0,9928
0 0 0
0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100
% algae inclusion in feed % algae inclusion in feed % algae inclusion in feed
The protein digestibility of the algae when extrapolating to 100% of protein
from algae were:
Phaeodactylum tricornutum: 79.9%
Nannochloropsis oceania : 35.5%
Isochrysis galbana : 18.8%

14. Apparent amino acid digestibility of LT fishmeal and the three algae
products
N. Oceania P. Tricornutum I. galbana LT fishmeal
Arg 41.2 87.4 56.8 93.6
His 17.2 76.6 37.1 88.9
Ile 30.3 75.9 63.5 92.4
Leu 30.9 81.6 68.6 93.0
Lys 38.1 84.5 12.6 86.8
Met 35.6 83.4 64.8 93.5
Trp 38.3 81.7 69.0 85.6
Phe 31.9 83.2 69.2 90.3
Thr 50.1 83.0 55.0 85.0
Val 31.6 82.2 62.5 91.4

15. Apparent crude fat digestibility of the algae
products
Nannochloropsis Phaeodactylum tricornutum Isochrysis galbana
100 100 100
90 90 90
80 80 80
70 70 70
% CL digested
% CL digested
% CL digested
60 60 60
50 50 50
40 40 40
30 30 30
20 y = -0,5587x 2 + 0,2459x + 98,032 20 y = -0,1732x 2 - 0,2497x + 98,107 20 y = -0,0746x 2 - 0,1763x + 98,186
R2 = 0,9998 R2 = 1 R2 = 0,9988
10 10 10
0 0 0
0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100
% algae inclusion in feed % algae inclusion in feed % algae inclusion in feed
Although the algae products represented a minor proportion of total dietary lipids some
indications were observed:
All algae products gave a reduction in lipid digestibility with increasing inclusion of algae lipids.
Calculation of the digestibility of lipids in the algae products would result in negative
digestibility.

16. Functional properites in microalgae
Foto: T. Landsverk
Hypotheses: A: Fiskemel
Normal gut
Certain microalgae may have
.
beneficial health effects
Soybean meal was used as a
model to study gut health
Feeding soybean meal results in: B: Soyamel
Soy-induced enteritis
 Enteritis in the distal intestine
 Reduced feed intake, growth, and
digestibility
 Reduced enzyme activity and bile salt levels
in the intestine

17. Microalgae in feed containing 20% SBM
Degree of inflammation in distal intestine
2.0
+
+
+
+
Leukocytes in Lamina Propria
Feed, % FM SBM ALG 1.5
Epithelial changes
Atrophy
Fishmeal 71 51 29.5 Oedema
* = different from SBM at p<0.01
Soybean + = different from FM at p<0.01
meal 0 20 20 1.0
Microalgae - - 20
D
d
n
h
a
o
g
c
r
e
s
t
f
l
i
0.5
*
*
*
*
*
*
*
*
0.0
SBM (Pos. ctrl.) FM (Neg. ctrl.) ALG (SBM + alga)
Diet
APC, 2012, unpublished

18. Conclusion - 1
• Microbes represent very promising feed ingredients
• They are sustainable feed resources - they do not
require agricultural land, use little water (or recycling)
and can be made from non-food raw materials
• Micro algae have some limitation concerning opening
up the cell-walls and low digestibility of nutrients in
several species
• Some microbes (both bacteria, yeast and microalgae)
contain many interesting bioactive components that
can give positive health effects
• The positive health effects are very species (and
possibly also strain) specific

19. Conclusion - 2
• To be successful, microbial ingredients must have a
high nutritional value (omega 3)/health benefits and
be produced economically
• Revisions of EU regulations on microbial protein
sources (Regulation (EC) No 767/2009) will facilitate
further development and use of such products as feed
ingredients