EFFECTS OF DIETARY SOYBEAN
LECITHIN ON CHANNEL CATFISH:
GROWTH, INNATE IMMUNE RESPONSE, LIPID
BIOCHEMICAL INDICES, & VALUE OF FILLETS FOR
HUMAN HEALTH
Todd Sink & Rebecca Lochmann
University of Arkansas at Pine Bluff
Catfish Lipid Requirements
n-3 fatty acid requirements
(Satoh et al. 1989)
known
n-6 requirements not fully
established
No known requirement for
phospholipids (PL)
Dietary sources
Synthesis (older fish)
Phospholipids
Major lipid class in biomembranes
Vital to physiological processes
Nutrient digestion, absorption &
transport
Immature fish often cannot
synthesize PL
(Fontagne et al. 2000)
Dietary PL essential for growth,
survival, feed utilization in some
fish fry
Phospholipid Sources
Concentrated sources of PL =>
Eggs, processed soy, & brain
Lecithin from soybeans- mixture
of PL & glycolipids
High conc phosphatidylcholine
(PC) & phosphatidylinositol (PI)
PC & PI demonstrated most
benefits in fish
(Coutteau et al. 1997)
Phospholipid Benefits
Benefits of dietary PL to
juvenile fish:
Improved growth
Increased survival
Increased body fat
Improved FCR
Resistance to stress
Improved health responses
Experimental Objectives
Determine if PL rich soybean
lecithin diets can:
1)
2)
3)
Improve catfish growth & health
Improve lipid & cholesterol
composition
Assess changes in blood
biochemistry - plasma lipids
Relative to lower PL diets
Feeding Trial
Twenty channel catfish - 15 tanks
Fed 3 isonitrogenous experimental
diets
Soy lecithin substituted
Inverse proportions to soybean oil
Fed twice daily to satiation - 6 weeks
Weight gain & survival sampled every
other week
Diet Composition
Ingredient
Menhaden fish
meal (65%)
Soybean meal
(48%)
Cottonseed meal
(41%)
Corn
Diet 1
Diet 2
(32%)
control
(32 %) (32 %)
5
5
Diet 3
5
Composition
(DM basis)
Diet 1
Diet 2 Diet 3
control
Protein
32.0
32.4
33.7
Lipid
8.5
7.9
7.8
44
44
44
Dry matter
86.3
85.3
89.8
8
8
8
Ash
6.8
6.9
7.2
Soybean oil
13
23
2
1
4
13
23
2
1
2
13
23
2
1
0
Soybean lecithin
0
2
4
Wheat midds
Vitamin premix
Mineral premix
Composition Soybean Soybean Diet 1 Diet 2 Diet 3
oil
lecithin control
Total Lipid
100.1
81.6
8.5
(g/100g lipid)
1.6
97.8
50.2 76.4 92.0
Phosphatidylcholine
6.5
69.7
34.5 60.1 71.6
(g/100g)
Phospholipid
(g/100g PL)
7.9 7.8
Blood Biochemistry
Blood collected 2 fish/tank
Health
Mean corpuscular hemoglobin conc
Lysozyme activity
(standard methods)
Alternative complement activity
Plasma lipid concentrations
Total cholesterol (Cholesterol esterase/oxidase FIA)
Triglycerides (TAG) (glycerol phosphate oxidase)
Phospholipids
(adsorption chromatography)
Phosphatidylcholine
(choline oxidase)
Tissue Composition
Liver removed
Hepatosomatic index (HSI)
Glycogen
Total lipid
Phospholipid
(Pflüger method)
(chloroform/methanol method)
(solvent fractionation)
Tissue 3 fish/tank
Whole-body proximate composition
Total lipid
Phospholipid
(chloroform/methanol method)
(solvent fractionation)
Growth
100% Survival
Mean Ind. Gain (g)
40
35
Week 2
Week 4
Week 6
30
25
20
15
10
5
30.3
21.5
15.5
33.9
23.8
16.6
32.5
22.4
15.7
0
4% SO
4% 50/50
Initial weight 5.8 ± 0.02 g
4% Lecithin
Percent Gain
800
Week 2
Week 4
Week 6
Final
Initials
Weight gain (%)
700
600
500
400
300
200
619
469
365
687
662
512
386
486
371
4% 50/50
4% Lecithin
100
0
4% SO
Diet
Feed Conversion Ratio
1.6
Week 2
a
1.5
Week 4
a
a,b
1.4
b
1.3
1.2
Week 6
1.48
1.36
1.44
1.25
1.1
1.29
1.37
b
b
1.31 1.34 1.34
1
4% SO
4% 50/50
4% Lecithin
Whole-body Tissue
Initial
4% SO
4% 50/50 4% Lecithin
(Mean ± SE)
Protein (%CP)
Lipid (%TL)
DM (%)
Ash (%)
11.6
2.2
18.8
2.8
13. 0 (0.5)a
9.7 (0.8)
28.8 (1.1)
2.7 (0.1)
15.0 (0.4)b
9.8 (0.3)
26.8 (1.0)
2.4 (0.3)
13.6 (0.2)a,b
8.9 (0.2)
26.1 (0.7)
2.5 (0.2)
%TL as PL
49.2
33.1 (3.6)
39.5 (6.0)
32.3 (3.3)
% PL as PC
42.6
51.1 (0.8)a
56.3 (0.6)b
58.3 (0.3)b
Health
4% SO 4% 50/50 4% Lecithin
% hematocrit
27.7
29.6
29.7
Hemoglobin (g/dL)
5.3
5.6
5.4
Mean corpuscular
hemoglobin conc.(g/dL)
19
19.7
19.1
Alternative complement
activity (50%)
Lysozyme (units/mL
plasma)
10.6
7.3
9.0
89.7
106.7
120.4
Plasma Lipids
12
TAG (g/L)
Cholesterol (g/L)
PC (g/L)
10
g/L
8
6
4
2
0
a
10.53
5.94
a,b
8.98
8.9
5.2
1.35
1.27
4% SO
4% 50/50
b
4.36
1.31
4% Lecithin
Liver Composition
HSI-No differences
12
Glycogen
a
b
% liver weight (wet basis)
10
8
6
4
10.8
6.47
b
70
b
b
b
a
% TL as PL
80
Lipid
60
b
a
50
40
9.6
9.5
7.61
7.99
30
20
2
67.0
71.7
50.7
10
0
0
4% SO
4% 50/50
4% Lecithin
4% SO
4% 50/50 4% Lecithin
Growth & Survival
No differences
Estimated dietary PL requirement for
most fry - 1-3%
(Coutteau et al. 1997)
Practical diets
(FM 10% lipid)
Control diet 4.25% PL
Dietary PL requirement met
Additional supplementation did
not improve growth
Feed Conversion
Improved with PL supplemention
Improve water stability of pellet
Increase nutrient stability
Antioxidant properties of PL
Enhance palatability & consumption
Greater availability of energy &
EFA from PL than neutral lipids
(Coutteau et al. 1997)
Phospholipids & Liver
Decreased plasma PC, decreased liver
glycogen, increased liver lipid & PC
Metabolic lipid repartitioning
Study fish fasted
Lecithin supplemented fish tissue saturated
with PC
Soybean oil fed fish mobilize PC to areas of
need
PL enhance lipid transport
(Niu et al. 2007)
May affect winter or starvation survival
Acknowledgements
We would like to thank the
Arkansas Soybean Promotion
Board for funding this study.
Questions???????