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Articles

Dietary Conjugated Linoleic Acids and Lipid Source Alter Fatty Acid Composition of Juvenile Yellow Perch, Perca flavescens¹

Department of Forestry and Natural Resources and ^* Department of Food Science, Lipid Chemistry and Molecular Biology Laboratory, Purdue University, West Lafayette, IN 47907-1159

²To whom correspondence should be addressed. E-mail: pb{at}fnr.purdue.edu.

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION LITERATURE CITED

 
A study was conducted to examine the effects of dietary conjugated linoleic acids (CLA; 0, 0.5 or 1.0 g/100 g total CLA) and lipid source (menhaden oil, soybean oil or a 1:1 mixture of menhaden:soybean oil) on growth rates and fatty acid composition of yellow perch. Dietary treatments were fed to apparent satiation to triplicate groups of fish initially weighing 37.9 g/fish. At the end of the 9-wk feeding trial, no significant differences were detected in weight gain or feed intake among fish fed any of the dietary treatments. Dietary CLA, lipid source and/or their interaction significantly affected feed efficiency, total liver lipid concentration, and muscle and liver fatty acid concentrations. Feed efficiency (g gain/g feed) was significantly lower in fish fed diets containing soybean oil (0.51) compared with fish fed menhaden oil (0.58) or menhaden:soybean oil (0.60). Liver total lipid concentrations were significantly reduced in fish fed 0.5 and 1.0 g/100 g CLA compared with fish fed the diets containing no CLA and in fish fed menhaden oil compared with those fed soybean oil or a 1:1 mixture of menhaden:soybean oil. Total CLA levels increased in both liver and muscle as dietary CLA concentration increased, irrespective of lipid source. However, total CLA concentrations were significantly lower in liver and muscle of fish fed soybean oil. Total muscle CLA concentrations were 0, 1.26 and 2.92 g/100 g fatty acids in fish fed diets containing menhaden oil and 0, 0.5 and 1.0 g/100 g CLA, respectively. Mono- and polyunsaturated fatty acid (PUFA) concentrations were significantly lower in muscle and liver of fish fed CLA compared with fish fed the diets containing no CLA. In contrast, liver concentrations of saturated fatty acids, 14:0, 16:0 and 18:0, were significantly higher in fish fed 1.0 g/100 g CLA.

KEY WORDS: • conjugated linoleic acids • fatty acids • (n-3)/(n-6) fatty acid ratio • fish

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION LITERATURE CITED

 
Conjugated linoleic acids (CLA)³ have become one of the focal points in fatty acid research, largely because of their health benefits (1 2 3 4) . They also improve production characteristics in several animals (5 ,6) , including fish (7) . CLA concentrations in muscle of fish have been among the highest of any animal examined.

Muscle CLA concentrations of carp (Cyprinus carpio), tilapia (Oreochromis niloticus) and rockfish (Sebastes schlegeli) fed 1.0 g/100 g dietary CLA were 13.0, 4.1 and 5.1 g/100 g fatty acids, respectively (8) . In hybrid striped bass (Morone chrysops x M. saxatilis), muscle CLA concentrations were 8.1 g/100 g fatty acids in fish fed diets containing 1.0 g/100 g CLA (7) . The CLA content of ruminant animals that naturally produce these fatty acids is much lower, ranging from 0.27 g/100 g fatty acids in veal to 0.56 g/100 g fatty acids in lamb (9) . Thus, consumption of CLA-supplemented fish may be an efficacious means of increasing human intake of these fatty acids.

Little is known about lipid metabolism in yellow perch (Perca flavescens). Perch accumulate low levels of lipid in muscle and appear tolerant of a wide range of dietary lipids (10) . Growth rates were not significantly different among yellow perch fed cold-pressed soybean oil, menhaden oil or a 1:1 mixture of cold-pressed soybean oil and menhaden oil, and there was no clear indication of the essential fatty acid (EFA) (10) . Muscle lipid concentrations in this species have typically been < 4 g/100 g on a dry matter basis. Our previous CLA study was with hybrid striped bass, a fish that accumulates relatively high levels of lipid in both liver and muscle (7) . The comparison of yellow perch with hybrid striped bass could be an important model for the study of CLA and other fatty acids in fish. However, the effects of CLA have not been evaluated in yellow perch.

The objective of this study was to determine the effects of graded levels of dietary CLA and various lipid sources on growth rates and fatty acid composition of yellow perch.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION LITERATURE CITED

 
Fish and animal husbandry.

Juvenile yellow perch (Perca flavescens) (all female) were obtained from a commercial producer (Coolwater Farms, Cambridge, WI) and transported to the Purdue University Aquaculture Research Facility. Procedures used during transport, quarantine and the experimental period were approved by the Purdue Animal Care and Use Committee (PACUC No. 89–060-98, "Nutritional Studies with Aquatic Animals," Principal Investigator Qualification No. BRO-249).

The closed recirculating system contained 30 individual 114-L aquariums and was equipped with two submerged filtration tanks for solid material removal and denitrification of the water. Water was pumped through a sand filter to each aquarium at a rate of 1 L/min. Water temperature was maintained at 21 ± 1°C throughout the experiment. The diurnal light:dark cycle of the aquaculture facility remained at 16 h light:8 h dark throughout the study.

Groups of 20 randomly chosen fish were stocked into each of 27 aquariums. Fish were acclimated to the experimental system for 3 wk before the experiment. All fish were fed a commercial diet during wk 1 of the acclimation period and their respective experimental diets thereafter. Dietary treatments were randomly assigned to triplicate aquariums. All fish were fed two times per day to satiation during acclimation and the experimental period. After the acclimation period, the number of fish in each tank was reduced to 15 so that the total weight of fish in each tank was 569.0 ± 5.0 g. The study was conducted for 9 wk. Water quality was monitored daily and was within acceptable limits throughout the study. Dissolved oxygen concentrations were not < 7.8 mg/L at any time. Ammonia-N and nitrite-N concentrations did not exceed 0.12 mg/L and 0.02 mg/L, respectively.

Diets.

The basal diet was formulated to provide 34.6 g/100 g crude protein. Casein and gelatin provided a total of 10.1 g/100 g crude protein and an L-amino acid mixture supplied the remaining 24.5 g/100 g crude protein (Table 1 ). The L-amino acid mixture was formulated so that the diets contained 1.6 g/100 g arginine (11) , 1.0 g/100 g total sulfur amino acids (12) and 1.2 g/100 g lysine (13) , thus meeting the dietary requirements of yellow perch for these amino acids. The remaining dietary essential amino acid concentrations met or exceeded the highest known requirements for fish (14) . Dietary choline concentration was maintained at 629 mg choline/kg diet with choline chloride (15) . The basal diet contained 8.0 g/100 g lipid and 25.0 g/100 g carbohydrate (dextrin).

The experiment was designed as a 3 x 3 factorial with three levels of CLA and three lipid sources. The nine treatments contained either 0, 0.5 or 1.0 g/100 g CLA in diets containing menhaden oil, soybean oil or a 1:1 mixture (wt:wt) of menhaden:soybean oil. The CLA supplement was added to the diets at the expense of lipid to maintain a constant energy level among all dietary treatments. The CLA supplement contained 30.6 g/100 g 18:2(c-9,t-11; t-9,c-11), 30.1 g/100 g 18:2(t-10,c-12), 2.5 g/100 g 18:2(t-9,t-11; t-10,t-12) and 1.5 g/100 g 18:2(c-9,c-11; c-10,c-12). Methods used in the CLA analysis were similar to those reported previously (7) . Fatty acid composition of the diets is presented in Table 2 . Diets were mixed and pelleted as previously reported (7) .

All fish were anesthetized (tricaine methanesulfonate, Argent Chemical, Redmond, WA) and weighed 24 h after the final feeding. Fillets were obtained from three randomly chosen fish in each dietary replicate group, pooled and frozen at -20°C for subsequent determination of moisture and total lipid levels. Moisture concentration was determined by drying fillets for 24 h in a forced-air oven maintained at 100°C. Lipid concentration of muscle was determined as described by Folch et al. (16) . Livers were also removed and weighed for calculation of relative liver weight (liver weight x 100/body weight). The livers were then frozen at-20°C for subsequent determination of total lipids. Visceral fat was also removed from each fish for calculation of the intraperitoneal fat (IPF) ratio (IPF weight x 100/body weight).

Analysis of fatty acids.

Liver and muscle samples were obtained from one randomly chosen fish in each dietary replicate group (n = 9) for determination of fatty acid composition. Samples were extracted with chloroform/methanol (2:1, v/v) and fatty acid methyl esters (FAME) prepared using 0.5 mol/L sodium methoxide in anhydrous methanol following procedures described by Li and Watkins (17) . Samples of diet also were subjected to lipid extraction and FAME produced (17) . The FAME were quantified using a gas chromatograph (HP 5890 series II, autosampler 7673, HP 3365 ChemStation; Hewlett-Packard, Avondale, PA) equipped with a DB23 column (30 m, 0.53 mm i.d., 0.5-µm film thickness; J&W Scientific, Folsom, CA) and operated at 140°C for 2 min, temperature programmed 1.5°C/min to 198°C and held for 7 min. The injector and flame ionization detector temperatures were 225 and 250°C, respectively. FAME were identified by comparison of retention times with authentic standards [GLC-422, CLA (UC-59-A and UC-59-M), Nu-Chek-Prep (Elysian, MN); CLA (Cat# 1245, c-9,t-11 and Cat# 1181, t-9,t-11) Matreya (Pleasant Gap, PA)] and FAME prepared from menhaden oil (Matreya).

Statistical analyses.

Data were analyzed as a completely randomized, 3 x 3 factorial design using each aquarium as an experimental unit. The data were subjected to two-way ANOVA using the Statistical Analysis System (SAS Institute, Cary, NC). Main effects were dietary CLA concentration and lipid source. Student-Neuman-Keuls test separated mean values when significant differences were detected by ANOVA. Accepted level of significance was 0.05.

	RESULTS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION LITERATURE CITED

 
There were no mortalities during the experiment. Weight gain, feed intake, IPF ratio and relative liver weight were not significantly affected by dietary treatments (Table 3 ). However, feed efficiencies (FE; g weight gain/g dry feed) were significantly lower in fish fed soybean oil compared with those fed menhaden oil or a 1:1 mixture of menhaden:soybean oil. Dietary CLA or the interaction between CLA and lipid source did not significantly affect FE. Liver moisture concentrations were significantly affected by dietary lipid source and by CLA concentration, but not the interaction of CLA and lipid source (Table 3) . Liver moisture concentrations were significantly higher in fish fed diets containing menhaden oil compared with fish fed soybean oil or a 1:1 mixture of menhaden:soybean oil and significantly higher in fish fed 0.5 g/100 g CLA compared with fish fed no CLA. Values for fish fed 1.0 g/100 g CLA were intermediate to those of fish fed 0 and 0.5 g/100 g CLA. Liver total lipid concentration was significantly affected by dietary lipid source, CLA concentration and their interaction. Liver total lipid concentration was significantly lower in fish fed 0.5 and 1.0 g/100 g CLA compared with fish fed no CLA and significantly lower in fish fed menhaden oil compared with those fed soybean oil or a combination of menhaden and soybean oil. Moisture and lipid concentrations of muscle were not significantly affected by dietary lipid source or CLA. However, muscle lipid concentration was significantly affected by the interaction of CLA and lipid source (Table 3) .

Dietary CLA significantly influenced muscle fatty acid concentrations (Table 5 ). Muscle concentrations of each CLA isomer, 18:2(c-9,t-11;t-9,c-11), 18:2(t-10,c-12) and 18:2(c-9,c-11;c-10,c-12), significantly increased with increasing dietary CLA. Total muscle CLA concentrations of fish fed menhaden oil and 0, 0.5 and 1.0 g/100 g CLA were 0, 1.26 and 2.92 g/100 g fatty acids, respectively. Concentrations of 18:0 also significantly increased as dietary CLA increased. In contrast, muscle concentrations of 16:1(n-7), 18:1(n-7) and 18:3(n-6) were significantly lower in fish fed 0.5 or 1.0 g/100 g CLA compared with fish fed no CLA. Concentrations of 20:2(n-6) were significantly lower in fish fed 1.0 g/100 g CLA compared with fish fed 0 and 0.5 g/100 g CLA. Total (n-6) PUFA concentrations were significantly higher in muscle of fish fed 0.5 g/100 g CLA (11.16 g/100 g fatty acids) compared with fish fed 1.0 g/100 g CLA (9.13 g/100 g fatty acids); intermediate concentrations were detected in fish fed no CLA (10.13 g/100 g fatty acids).

	DISCUSSION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION LITERATURE CITED

 
Dietary CLA did not significantly affect weight gain, feed intake or feed efficiency in the current study, but did exert significant effects on whole-animal performance variables in other studies. Feed intake and weight gain of hybrid striped bass fed 1.0 g/100 g CLA were significantly lower and FE were significantly higher than those of fish fed a diet without CLA (7) . However, tilapia and rockfish fed diets containing 2.5–10.0 g/100 g CLA and carp fed 10.0 g/100 g CLA exhibited significantly lower weight gain and FE compared with fish fed diets containing no CLA (8) . Mice fed dietary CLA concentrations of 0.5–1.5 g/100 g exhibited significantly lower weight gain and FE compared with those fed a control diet (8 ,18 19 20) . Efficiency of feed utilization was increased in rats (17) and pigs (5) fed diets containing CLA. The variation across species in weight gain, consumption and FE may be a reflection of the differences in fatty acid metabolism in the liver and the ability of the animal to use those fatty acids transported to extrahepatic tissues either as a source of energy or a source of EFA. The significant effect of treatments on liver moisture may have little biological importance because the values ranged from a low of 59.04 g/100 g to a high of 63.67 g/100g.

Results of the current study demonstrate that accumulation of CLA in fish tissues is dependent upon dietary lipid source. Muscle and liver concentrations of the CLA isomers 18:2(c-9,t-11; t-9,c-11) and 18:2(t-10,c-12) were significantly higher in fish fed menhaden oil compared with fish fed soybean oil diets; intermediate concentrations were observed in fish fed menhaden:soybean oil diets. There were significant changes in hepatic and muscle (n-3) and (n-6) fatty acids when CLA were fed to hybrid striped bass (7) , suggesting an interaction with dietary or tissue fatty acids. However, this is the first demonstrated interaction of CLA and dietary fatty acids in fish. Most response variables were not significantly altered by dietary lipid source. Feed efficiency, however, was significantly lower in fish fed soybean oil compared with fish fed menhaden oil. This may be an indication that soybean oil does not meet the EFA requirement of yellow perch.

In addition to the significant effects on FE, total liver lipid and hepatic 18:1(n-9) concentrations were significantly higher in fish fed soybean oil and the menhaden:soy mixture compared with fish fed menhaden oil. Each of those responses can be an indication of dietary EFA deficiency in fishes (21 ,22) . Similar to terrestrial vertebrates, fishes are unable to synthesize 18:2(n-6) and/or 18:3(n-3) (14) , and the ability to elongate and desaturate 18-carbon fatty acids varies among species of fish (23) . Generally, freshwater fish exhibit a dietary requirement for 18:2(n-6) and/or 18:3(n-3), and stenohaline marine fish require dietary 20:5(n-3) and/or 22:6(n-3) (14) . Thus, it is likely that soybean oil does not meet the fatty acid requirements of the freshwater yellow perch and that dietary (n-3) fatty acids are required for maximum growth rates and reduced tissue lipid concentrations in this species.

The muscle CLA concentrations of fish fed 1.0 g/100 g CLA and either menhaden oil, soybean oil or a 1:1 mixture of menhaden:soybean oil were 2.92, 1.89 or 2.87 g/100 g fatty acids, respectively. Muscle CLA concentrations were as high as 8.1 g/100 g fatty acids in hybrid striped bass fed 1.0 g/100 g CLA and 3.4 g/100 g in fish fed 0.5 g/100 g CLA (7) . Muscle CLA concentrations in carp, tilapia and rockfish fed 1.0 g/100 g dietary CLA were 13.0, 4.1 and 5.1 g/100 g fatty acids, respectively (8) . These data indicate that the ability of fish to accumulate CLA is dependent upon the species of fish and the dietary lipid source. Part of the observed difference may be due to differences in muscle lipid concentrations. Total muscle lipid concentrations in hybrid striped bass were 14.3–18.2 g/100 g dry muscle (7) , which are higher than those in yellow perch (2.5–3.3 g/100 g). Also, feed consumption, and thus CLA intake, was higher in hybrid striped bass (52.1–61.1 g dry feed/fish) compared with yellow perch (22.8–23.3 g dry feed/fish). Levels of CLA in those animals that naturally produce CLA are 0.27–0.56 g/100 g fatty acids (9 ,24) . The CLA content of cheese and milk fat is 0.30–0.70 g/100 g fatty acids (9 ,24) . Thus, of the animals evaluated, fish are apparently able to accumulate higher concentrations of CLA than other vertebrates.

Yellow perch fed 0.5 and 1.0 g/100 g CLA had significantly lower liver lipid concentrations compared with fish fed no CLA. Similarly, hybrid striped bass fed 1.0 g/100 g CLA had significantly lower liver total lipid concentration and IPF ratio compared with fish fed a control diet containing no CLA (7) . Dietary CLA have also been shown to modify the body composition of rodents. Park et al. (25) fed mice 0.5 g/100 g CLA and found a significant reduction in body fat and a significant increase in body protein. They demonstrated that dietary CLA reduced body fat by increasing carnitine palmitoyltransferase activity in fat pad and skeletal muscle. Furthermore, CLA reduced lipoprotein lipase activity and intracellular triacylglyceride concentrations in cultured 3T3-L1 adipocytes (25) . The same investigators recently found that the 18:2(t-10,c-12) isomer was responsible for reduced lipoprotein lipase activity and intracellular triacylglycerol concentrations in 3T3-L1 adipocytes (26) . However, dietary CLA increased liver lipid concentrations in other studies with rodents (18 ,27) . The reasons for these conflicting results are not readily apparent, but may be due to differences in CLA composition used in the various studies.

Fatty acid compositions of liver and muscle of yellow perch were significantly different in fish fed CLA and fish fed the diets containing no CLA. Liver concentrations of several saturated fatty acids (14:0, 16:0 and 18:0), as well as CLA, were significantly higher in fish fed 1.0 g/100 g CLA compared with fish fed no CLA (Table 4) . In contrast, total (n-3) and (n-6) PUFA were significantly lower in liver of fish fed CLA compared with fish fed the control diets containing no CLA. Muscle fatty acid concentrations were less affected by dietary CLA. Muscle concentrations of the saturated fatty acid, 18:0, and CLA were significantly increased, whereas concentrations of 16:1(n-7), 18:1(n-7) and 20:2(n-6) were significantly reduced in fish fed 1.0 g/100 g CLA. Thus, it is apparent that CLA altered the metabolism of other fatty acids in yellow perch perhaps through competition as substrates for various enzymatic reactions.

Dietary CLA also modified fatty acid concentrations in liver and muscle of hybrid striped bass (7) . Liver concentrations of several (n-3) PUFA, 20:5(n-3), 22:5(n-3) and 22:6(n-3), were significantly higher in hybrid striped bass fed 1.0 g/100 g CLA compared with fish fed other levels of CLA or in fish fed no CLA. In contrast, muscle concentrations of 20:5(n-3) and 22:6(n-3) were significantly lower in fish fed 1.0 g/100 g CLA compared with fish fed no CLA. Thus, dietary CLA resulted in accumulation of saturated fatty acids in liver of yellow perch, whereas (n-3) PUFA accumulated in liver of hybrid striped bass fed CLA. In both fish species, muscle fatty acid concentrations generally decreased as dietary CLA levels increased. The reasons for the differential effects of dietary CLA on liver fatty acid concentrations in these two species are not readily apparent, but may reflect differences in EFA or fatty acid metabolism.

The CLA isomers 18:2(c-9,c-11;c-10,c-12) were present at low levels (1.5 g/100 g) in the commercial supplement used in our study, but were not detected in the diets that contained CLA. Because the diets contained a maximum of 1.0 g/100 g CLA supplement, dietary levels of those isomers were likely below the detection limits of the gas chromatograph. However, those isomers were detected in liver and muscle of yellow perch fed CLA. In contrast, the 18:2(t-9,t-11;t-10,t-12) isomers were present in the supplement and detected in the diets that contained the CLA supplement, but were not found in tissues of the fish fed CLA. These results are likely explained by interconversion of CLA isomers by gut microflora and possibly by preferential metabolism by liver enzymes. Absence of the 18:2(t-9,t-11;t-10,t-12) isomers in both tissues likely resulted from preferential oxidation of these isomers, because cis double bonds of fatty acids must be converted to the trans form to complete ß-oxidation.

Results of research conducted to date indicate that fish are able to accumulate relatively high levels of CLA compared with ruminant species (7 ,8 ,24) . Results have also shown that tissue concentrations were dependent upon species, dietary lipid source, and the amounts and types of CLA consumed by those fish.

	FOOTNOTES

 
¹ Supported by the Purdue University Agricultural Research Programs, technical manuscript #16545.

³ Abbreviations used: CLA, conjugated linoleic acids; EFA, essential fatty acids; FAME, fatty acid methyl esters; FE, feed efficiency; IPF, intraperitoneal fat; PUFA, polyunsaturated fatty acids.

Manuscript received March 27, 2001. Initial review completed May 4, 2001. Revision accepted June 14, 2001.

	LITERATURE CITED

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION LITERATURE CITED

 

1. Ip C. (1994) Conjugated linoleic acid in cancer prevention research: a report of current status and issues. Research Report No. 100–104. Special Report Prepared for the National Livestock and Meat Board 1994 Washington, DC .

2. Ip C., Chin S. F., Scimeca J. A. & Pariza M. A. (1991) Mammary cancer prevention by conjugated derivatives of linoleic acid. Cancer Res 51:6118-6124.[Abstract/Free Full Text]

3. Parodi P. W. (1996) Milk fat components: possible chemopreventive agents for cancer and other diseases. Aust. J. Dairy Technol. 51:24-32.

4. Scimeca J. A., Thompson H. J. & Ip C. (1994) Effects of conjugated linoleic acid on carcinogenesis. Weisburger E. K. eds. Diet and Breast Cancer 1994:59-65 Plenum Press New York, NY. .

5. Dugan M.E.R., Aalhus J. L., Schaefer A. L. & Kramer J.K.G. (1997) The effect of conjugated linoleic acid on fat to lean repartitioning and feed conversion in pigs. Can. J. Anim. Sci. 77:723-725.

6. Haumann B. F. (1996) Conjugated linoleic acid offers research promise. INFORM 7:152-159.

7. Twibell R. G., Watkins B. A., Rogers L. & Brown P. B. (2000) Effects of dietary conjugated linoleic acids on hepatic and muscle lipids in hybrid striped bass. Lipids 35:155-161.[Medline]

8. Choi B.-D., Kang S.-J., Ha Y.-L. & Ackman R. G. (1999) Accumulation of conjugated linoleic acid (CLA) in tissues of fish fed diets containing various levels of CLA. Xiong Y. L. Ho C.-T. Shahidi F. eds. Quality Attributes of Muscle Foods 1999:61-71 Kluwer Academic/Plenum Publishers New York, NY. .

9. Watkins B. A. & Li Y. (2001) Conjugated linoleic acid: the present state of knowledge. Wildman R. eds. Handbook of Nutraceuticals and Functional Foods 2001:443-474 CRC Press Boca Raton, FL. .

10. Cartwright D. (1998) Dietary Lipid Studies with Juvenile Yellow Perch. M.S. thesis 1998 Purdue University West Lafayette, IN. .

11. Twibell R. G. & Brown P. B. (1997) Dietary arginine requirement of juvenile yellow perch. J. Nutr. 127:1838-1841.[Abstract/Free Full Text]

12. Twibell R. G., Wilson K. A. & Brown P. B. (2000) Dietary sulfur amino acid requirement of juvenile yellow perch fed the maximum cystine replacement value for methionine. J. Nutr. 130:612-616.[Abstract/Free Full Text]

13. Twibell R. G., Cartwright D. D., Wilson K. A. & Brown P. B. (1998) Dietary lysine requirement of juvenile yellow perch. World Aquaculture ’98, Las Vegas, NV (abs.) 1998.

14. National Research Council (1993) Nutrient Requirements of Fish 1993 National Academy Press Washington, DC. .

15. Twibell R. G. & Brown P. B. (2000) Dietary choline requirement of juvenile yellow perch (Perca flavescens). J. Nutr. 130:95-99.[Abstract/Free Full Text]

16. Folch J., Lees M. & Sloan-Stanley G. H. (1957) A simple method for the isolation and purification of total lipides from animal tissues. J. Biol. Chem. 226:497-509.[Free Full Text]

17. Li Y. & Watkins B. A. (1998) Conjugated linoleic acids alter bone fatty acid composition and reduce ex vivo prostaglandin E₂ biosynthesis in rats fed (n-6) or (n-3) fatty acids. Lipids 33:417-425.[Medline]

18. Belury M. A. & Kempa-Steczko A. (1997) Conjugated linoleic acid modulates hepatic lipid composition in mice. Lipids 32:199-204.[Medline]

19. Hayek M. G., Han S. N., Wu D., Watkins B. A., Meydani M., Dorsey J. L., Smith D. E. & Meydani S. N. (1999) Dietary conjugated linoleic acid influences the immune response of young and old C57BL/6NCrlBR mice. J. Nutr. 129:32-38.[Abstract/Free Full Text]

20. West D. B., Delany J. P., Camet P. M., Blohm F., Truett A. A. & Scimeca J. (1998) Effects of conjugated linoleic acid on body fat and energy metabolism in the mouse. Am. J. Physiol. 275:R667-R672.

21. Ruyter B., Rosjo C., Einen O. & Thomassen M. S. (2000) Essential fatty acids in Atlantic salmon: time course of changes in fatty acid composition of liver, blood and carcass induced by a diet deficient in (n-3) and (n-6) fatty acids. Aquacult. Nutr. 6:109-117.

22. Tacon A.G.J. (1996) Lipid nutritional pathology in farmed fish. Arch. Anim. Nutr. 49:33-39.

23. Bell J. G. (1998) Current aspects of lipid nutrition in fish farming. Black K. D. Pickering A. D. eds. Biology of Farmed Fish 1998:114-145 Sheffield Academic Press Sheffield, England. .

24. Chin S. F., Liu W., Storkson J. M., Ha Y. L. & Pariza M. W. (1992) Dietary sources of conjugated dienoic isomers of linoleic acid, a newly recognized class of anticarcinogens. J. Food Comp. Anal. 5:185-197.

25. Park Y., Albright K. J., Liu W., Storkson J. M., Cook M. E. & Pariza M. W. (1997) Effect of conjugated linoleic acid on body composition in mice. Lipids 32:853-858.[Medline]

26. Park Y., Storkson J. M., Albright K. J., Liu W. & Pariza M. W. (1999) Evidence that the trans-10, cis-12 isomer of conjugated linoleic acid induces body composition changes in mice. Lipids 34:235-241.[Medline]

27. Moya-Camarena S. Y., Vanden Heuvel J. P. & Belury M. A. (1999) Conjugated linoleic acid activates peroxisome proliferator-activated receptor and ß subtypes but does not induce hepatic peroxisome proliferation in Sprague-Dawley rats. Biochim. Biophys. Acta 1436:331-342.[Medline]

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