426
a. B. OOWEY AND J. R. SAROENT
of polyunsaturated fatty acids (polyenoic acids) in fish and other
animals ; these are listed in Table XII.
Tissue fatty acids of fish are derived from two sources ; firstly, from
the food and secondly by de novo biosynthesis within the fish. Furthermore, ingested fatty acids may be modified within the fish by desaturation and chain elongation. All lipid classes in the diet will contribute
fatty acids to the fish although on a normal diet the bulk of them will
be derived from triglycerides and phospholipids in about equaI
proportions (e.g. see Table XVI).
In considering the fatty acid requirements of fish some appreciation
of the spectrum of fatty acids commonly found in their lipid is usefuI.
Fatty acid analyses of lipid from freshwater and marine sources is
covered by a vast literature stemming from the original work of
Lovern in the 1930s. Fatty acids of fish are usually much more unsaturated than fatty acids from land animals because of their high
content of mono, di-, tri-, tetra-, penta- and hexaenoic acids (Lovern,
1942; Bailey, 1952; Lovern, 1964; Hilditch and Williams, 1964).
The concept has emerged that freshwater fats have higher amounts of
Cl6 and ClS fatty acids and lower amounts of C20 and C22 fatty acids
than marine fats.
TABLE XIII. DISTRIBUTION OF MAJOR FAW AOLDS IN VARIOWS FISE OILS
Fatty acid
Freshwater species
Marine species
hewing
cod
Sheepsheud
Tullibee Maria Alewife Atlantic Atlantic
14:O
14:l
16:O
16:l
18:O
18:l
18 : 2w6
18:3w3
20:l
20 : 406
20 : 6w3
22: 1
22 : 4w6
22 : 6w3
22 : 6w3
2.8
1.0
16.6
17.7
3.3
26.1
4.3
3.6
2.4
2-6
4.7
0.3
0.4
2.0
2.0
4.6
3.1
6.7
6.1
3.7
0.8
0.8
0.7
0.4
0.1
13.8
13.2
14.6
10.9
12.6
21.6
16.2
14.7
12.0
9.3
2.9
2-8
1.6
1.2
2.3
26.2
29.1
18.2
12.6
22.7
1.9
2.2
3-7
0.7
1-6
2-6
1.9
3- 6
0.3
0.6
1.3
1.2
1.6
16-1
7.6
1.7
2.4
2.4
0.4
1.4
6.2
6.6
8.2
7.4
12.9
0.3
0.3
0.4
19.8
6.2
0-3
0.4
0.4
-
0.1
1.8
2.4
1.6
1.1
1.7
3.8
7.8
6.0
3.9
12.7
Ratio of -
1.7
3.6
3.6
3.0
7-6
9.2
w3
w6
Data from Ackmtm (1967) expressed as weight per cent fatty acids; (-) signifies absent
or preeent i n traoe amounts.
a. B. OOWEY AND J. R. SAROENT
of polyunsaturated fatty acids (polyenoic acids) in fish and other
animals ; these are listed in Table XII.
Tissue fatty acids of fish are derived from two sources ; firstly, from
the food and secondly by de novo biosynthesis within the fish. Furthermore, ingested fatty acids may be modified within the fish by desaturation and chain elongation. All lipid classes in the diet will contribute
fatty acids to the fish although on a normal diet the bulk of them will
be derived from triglycerides and phospholipids in about equaI
proportions (e.g. see Table XVI).
In considering the fatty acid requirements of fish some appreciation
of the spectrum of fatty acids commonly found in their lipid is usefuI.
Fatty acid analyses of lipid from freshwater and marine sources is
covered by a vast literature stemming from the original work of
Lovern in the 1930s. Fatty acids of fish are usually much more unsaturated than fatty acids from land animals because of their high
content of mono, di-, tri-, tetra-, penta- and hexaenoic acids (Lovern,
1942; Bailey, 1952; Lovern, 1964; Hilditch and Williams, 1964).
The concept has emerged that freshwater fats have higher amounts of
Cl6 and ClS fatty acids and lower amounts of C20 and C22 fatty acids
than marine fats.
TABLE XIII. DISTRIBUTION OF MAJOR FAW AOLDS IN VARIOWS FISE OILS
Fatty acid
Freshwater species
Marine species
hewing
cod
Sheepsheud
Tullibee Maria Alewife Atlantic Atlantic
14:O
14:l
16:O
16:l
18:O
18:l
18 : 2w6
18:3w3
20:l
20 : 406
20 : 6w3
22: 1
22 : 4w6
22 : 6w3
22 : 6w3
2.8
1.0
16.6
17.7
3.3
26.1
4.3
3.6
2.4
2-6
4.7
0.3
0.4
2.0
2.0
4.6
3.1
6.7
6.1
3.7
0.8
0.8
0.7
0.4
0.1
13.8
13.2
14.6
10.9
12.6
21.6
16.2
14.7
12.0
9.3
2.9
2-8
1.6
1.2
2.3
26.2
29.1
18.2
12.6
22.7
1.9
2.2
3-7
0.7
1-6
2-6
1.9
3- 6
0.3
0.6
1.3
1.2
1.6
16-1
7.6
1.7
2.4
2.4
0.4
1.4
6.2
6.6
8.2
7.4
12.9
0.3
0.3
0.4
19.8
6.2
0-3
0.4
0.4
-
0.1
1.8
2.4
1.6
1.1
1.7
3.8
7.8
6.0
3.9
12.7
Ratio of -
1.7
3.6
3.6
3.0
7-6
9.2
w3
w6
Data from Ackmtm (1967) expressed as weight per cent fatty acids; (-) signifies absent
or preeent i n traoe amounts.