Improved nutritional value of fish feed with plant protein ingredients by means of organic acid salts

166 Pages·2016·3.01 MB·English

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Improved nutritional value of fish feed with plant protein ingredients
by means of organic acid salts and solid state fermentation

Forbedret næringsverdi i fiskefôr med planteproteinfôrmidler ved hjelp av
organiske syresalter og faststoff fermentering

Philosophiae Doctor (PhD) Thesis

Youling Gao

Depart. of Animal and Aquacultural Sciences
Norwegian University of Life Sciences

Ås 2011

Thesis number: 2011:23
ISSN: 1503-1667
ISBN: 978-82-575-0987-3

ACKNOWLEDGEMENTS
This research work was supported by the Research Council of Norway and Vitality
Innovation in Norway. The research was conducted at the Aquaculture Protein Centre, CoE,
Department of Animal and Aquacultural Science (IHA) and Department of Chemistry,
Biotechnology and Food Science (IKBM) at the Norwegian University of Life Sciences
(UMB). I was supported by a PhD scholarship from the China Scholarship Council (CSC). I
give my sincere thanks to these institutions for enabling me to fulfil my PhD degree.
I would like to express my sincere gratitude to my main supervisor Prof. Trond
Storebakken for accepting me as a PhD student and leading me into the world of fish nutrition
and feed technology. I really appreciate your guidance through the whole period of the
research work and your patience and time for review my papers and thesis. I also give my
honest gratitude to co-supervisor Prof. Margareth Øverland for her support on research
resources, arrangements, guidance and critical suggestions. Without you, I could not have
reached my goal. I also want to give my sincere thanks to my co-supervisor Research
Scientist Jon Fredrik Hanssen, for always giving me your best help when I worked at IKBM,
and making the experiments run smoothly. A special appreciation goes to Dr. Karl Douglas
Shearer. Although you are not in the list of my supervisor, your help has been that of a
supervisor. Your help was not only in my research, but also in my life. My acknowledgement
also is expressed to Dr. Liv Torunn Mydland for long hours of careful work to successfully
analyse amino acids from small samples, critical reviewing of all sorts of chromatograms, and
active efforts in writing the manuscripts and thesis.
Tamara Zimonja, Frank Sundby and Tone Stigen Martinsen at APC, I greatly
appreciate your skilful and professional contribution. I also received enormous help from
other colleagues in the FIP section that greatly contributed to the success of the experiments.
I give my deep appreciation to my colleagues. I am grateful to all colleagues in APC for
sharing professional discussions and social life. This made my work more enjoyable.
I would also like to thank all co-authors for their excellent collaborations.
I would like to give my appreciation to Dr. Guoying Qian in Zhejiang Wanli
University for being supportive to my study in Norway.
Thank you also to all my Chinese friends living in Ås who have support me and my
family a lot. We had a lot of great moments. Special thanks are given to Binbin Liu family,
Zhanliang Liu family and Hua Wei.
Finally, thanks are given to my parents for their understanding, support and
encouragement. I also would like to hug my wife Lingli Jiang, and our lovely son Wenji Gao
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(Nuonuo). I am really happy to have both of you in my life. Darling, thanks for support, love,
encouragement and patience during so many years. Nuonuo, papa loves you so much.

Ås, April 2011
Youling Gao

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TABLE OF CONTENTS 
ACKNOWLEDGEMENTS .................................................................................................................. 1
TABLE OF CONTENTS ...................................................................................................................... 3
LIST OF TABLES ................................................................................................................................ 4
LIST OF FIGURES .............................................................................................................................. 5
ABSTRACT ........................................................................................................................................... 6
SAMMENDRAG ................................................................................................................................... 8
CHINESE ABSTRACT ...................................................................................................................... 10
ABBREVIATIONS ............................................................................................................................. 12
LIST OF PAPERS ............................................................................................................................... 13
1. INTRODUCTION ........................................................................................................................... 14
2. OBJECTIVES OF THE STUDY ................................................................................................... 16
3. BACKGROUND .............................................................................................................................. 17
3.1 Organic acids and their salts ........................................................................................................ 17
3.2 Rapeseed meal ............................................................................................................................. 20
3.3 Solid state fermentation ............................................................................................................... 26
4. MAIN RESULTS AND DISCUSSION .......................................................................................... 36
4.1 Effect of an organic acid salt blend (OAB) of sodium formate and sodium butyrate on
digestibility and growth of rainbow trout and Nile tilapia ................................................................ 36
4.2 Effect of SSF on nutritional quality of rapeseed meal (Paper II, III) .......................................... 39
4.3 Fermented rapeseed meal in diets for tilapia (Paper II, III) ......................................................... 41
4.4 Hydro-thermal (steam) treatment does not improve nutritional value of fermented RSM in diets
for Nile tilapia (Paper IV) ................................................................................................................. 44
5. CONCLUSIONS .............................................................................................................................. 46
6. FUTURE PERSPECTIVES ........................................................................................................... 47
REFERENCES .................................................................................................................................... 48
PAPER I-IV ......................................................................................................................................... 58 

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LIST OF TABLES
Table 1. Mechanisms of organic acids and their salts
Table 2. Typical chemical composition of conventional rapeseed and Canola meals (dry
matter basis)
Table 3. Essential amino acid composition of conventional rapeseed meal, Canola meal and
soybean meal (proportion as % of crude protein)
Table 4. An overview of the results of selected studies where fermentation was used to
inactivate ANFs in plant protein sources
Table 5. An overview of the results of selected studies where fermented plant protein sources
were fed to fish

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LIST OF FIGURES
Figure 1. Model antimicrobial action of organic acid in the stomach
Figure 2. Rapeseed oil extraction and rapeseed meal production
Figure 3. General structure of glucosinolates
Figure 4. Scheme of glucosinolate hydrolysis
Figure 5. Micro structure of solid state fermentation with fungi
Figure 6. Apparent digestibility of main nutrients in the diets used in Experiment 1
Figure 7. Apparent digestibility of crude protein, total amino acids, essential amino acids and
cysteine in the diets used in Experiment 1
Figure 8. Feed conversion ratio in Experiment 1
Figure 9. Ratio of middle intestine to whole body weight (g kg-1)
Figure 10. Specific growth rate of the tilapia fed the moist diets
Figure 11. Feed conversion ratio of the tilapia fed the moist diets
Figure 12. Feed conversion ratio of the tilapia fed the extruded diets

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ABSTRACT
Gao, Y., 2011. Improved nutritional value of fish feed with plant protein ingredients by
means of organic acid salts and solid state fermentation. Norwegian University of life
Sciences, Philosophiae Doctor Thesis 2011:23, ISSN: 1503-1667, ISBN: 978-82-575-0987-3.

The objective of this work was to improve the nutritional value of plant protein sources to be
used in fish feed by means of organic acid salts and solid state fermentation (SSF). Four
studies were conducted to determine the effects of a blend of organic acid salts (OAB) in diets
for rainbow trout (Oncorhynchus mykiss) and Nile tilapia (Oreochromis niloticus), SSF
rapeseed meal in different types of diets for Nile tilapia, and thermal-hydro (steam) treatment
on nutritional value of fermented rapeseed meal in diets for Nile tilapia.
The first study was designed to evaluate the effects of adding an OAB (a mixture of
sodium formate and butyrate) to a fish meal-based diet and a diet where 36% of the fish meal
protein had been replaced by plant proteins (a mixture of soybean meal and pea protein
concentrate). The diets were fed to rainbow trout reared in freshwater. Adding OAB to the
plant protein-based diet before extrusion significantly reduced the digestibility of dry matter,
organic matter, crude fat, and most amino acids. Supplementation of OAB after extrusion
reduced the digestibility of crude fat both in the fishmeal and plant protein-based diets.
Inclusion of OAB in both fishmeal and plant protein-based diets before extrusion significantly
increased feed conversion ratio (FCR), and middle intestine to body weight ratio. Partly
replacing fishmeal with plant proteins reduced the digestibility of dry matter, organic matter,
crude fat, phosphorous and several amino acids, and increased FCR.
The second study was carried out to determine the potential of laboratory-scale aerobic
SSF with Aspergillus niger to increase the nutritional quality of rapeseed meal, and to
evaluate the potential for use of untreated (RSM) and fermented rapeseed meal (FRSM) in
diets for Nile tilapia. In Exp. 1, three moist diets were produced: a diet based on fish meal and
soybean meal (SBM), and two diets in which SBM was fully replaced by RSM or FRSM. In
Exp. 2, three extruded diets were produced with the same formulation as used in Exp. 1.
Phytic acid and glucosinolates in RSM were reduced, the content of crude protein increased
and total amino acids was decreased by SSF. In Exp.1, the growth rate of fish fed the SBM
diet was significantly lower than that of tilapias fed the RSM and FRSM diets. FCR of fish
fed RSM diet was significantly poorer than that of fish fed the SBM and FRSM diets. Fish fed
the RSM diet had significantly higher whole body protein than fish fed the SBM diet. In Exp.
2, the growth rate showed no significant difference among the dietary treatments, while FCR
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differed among all 3 treatments (SBM<RSM< FRSM). The nitrogen retention of fish fed
SBM diet was significantly higher than that of fish fed the RSM diet, which was higher than
that for FRSM. The digestibility of nitrogen in fish fed SBM diet was higher than for tilapia
fed the RSM and FRSM diets. The digestibility of Mg was significantly higher in fish fed the
SBM and FRSM diets than that in tilapias fed RSM. The differences in nutritional value in the
two experiments are rationalized by differences in the SSF process, and by the two methods
of feed production used.
The third study was conducted to evaluate the effects of supplementing the OAB to the
diets, in combination with medium-scale SSF of RSM on growth performance and apparent
nutrient digestibilities in Nile tilapia. The results showed that supplementing diets with the
OAB did not have other effects than increasing the stomach weight in percentage of body
weight. SSF of RSM reduced the feed intake, growth rate, liver weight percentage, increased
stomach weight percentage and FCR, and reduced whole-body dry matter, crude fat and
increased ash contents.  
The fourth study was conducted to evaluate the effect of short-term steam treatment
for pasteurisation of FRSM on growth performance, whole body composition and apparent
nutrient digestibilities in Nile tilapia. Two diets were prepared with and without steam
treatment after SSF of RSM. Steam treatment increased FCR, while growth rate, nutrient
digestibilities and protein retention were not affected.
In conclusion, supplementing the diets with an OAB did not improve the growth
performance of rainbow trout and Nile tilapia. Laboratory-scale SSF of RSM changed the
nutritional value and improved the FCR when used in a moist diet, while less efficient FCR
was found when used in an extruded diet. Medium-scale SSF of RSM reduced growth rate,
but improved FCR. Short-term steam treatment did not improve the nutritional quality of
FRSM as a dietary ingredient for Nile tilapia. 

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