Chen-Huei Huang

Dietary vitamin E supplementation affects tissue lipid peroxidation of hybrid tilapia, Oreochromis niloticus x O. aureus

A feeding trial was conducted to evaluate the effects of dietary vitamin E contents on the growth, ascorbate induced iron-catalyzed lipid peroxidation in post-mortem muscle and liver tissue, and Raman spectral changes in lens of juvenile hybrid tilapia (Oreochromis niloticus x O. aureus). Experimental fish were fed practical diets supplemented with 0, 50, 100, 200, 450 and 700 mg alpha-tocopheryl acetate/kg diet for 14 weeks. There was no significant difference in weight gain, feed conversion ratio and protein efficiency ratio among fish fed test diets (P>0.05). Protein content of fish fed diet containing the lowest vitamin E level was the lowest (P<0.05) among all groups. No difference was found in other body constituents among test fish (P>0.05). The thiobarbituric acid-reactive substances produced by iron-catalyzed lipid peroxidation in muscle and liver tissue of fish fed the diet without alpha-tocopheryl acetate supplementation were significantly (P<0.05) greater than those from fish fed diets containing higher levels of alpha-tocopheryl acetate. Dietary vitamin E supplementation increased the antioxidant capability of tilapia tissues against lipid peroxidation. Further, dietary vitamin E supplementation also influenced the lens cortical membrane structure of tilapia.

Effect of NaCl on catalysis of lipid oxidation by the soluble fraction of fish muscle

Sodium chloride stimulated catalysis of oxidation of phosphatidylcholine liposomes by the soluble fraction of mackerel muscle. Chloride was determined to be the active component of the salt in this system. Sulfate also stimulated lipid oxidation. No difference was observed with either anion among sodium, potassium, or lithium cations. Redox iron was involved in the chloride stimulation of lipid oxidation by the press juice. Part of the chloride stimulation of the press juice was mediated through the high molecular weight (greater than 5 kdalton) fraction. Chloride improved the pro-oxidative effect of ascorbate on rat liver ferritin in vitro. It did not appear that production of chlorine radical by peroxidase was involved in the stimulatory effect of chloride.

Effects of intermittent feeding on the growth of oophagous ( Chirixalus eiffingeri ) and herbivorous ( Chirixalus idiootocus ) tadpoles from Taiwan

The effects of intermittent feeding on the growth of oophagous Chirixalus eiffingeri and herbivorous Chirixalus idiootocus tadpoles were studied. Tadpoles were fed, once every 1, 2, 4, 8, 14, or 20 days (feeding treatments 1D, 2D, 4D, 8D, 14D, and 20D, respectively). At each feeding, C. eiffingeri were given yolk from chicken eggs, and those of C. idiootocus were given boiled spinach, ad libitum . For each species, each treatment consisted of 12 replicates of one tadpole each. For C. eiffingeri , the 1D feeding treatment was eliminated because the tadpoles were unwilling to eat daily. Chirixalus eiffingeri tadpoles in the 2D and 4D feeding treatments grew fastest, while tadpoles in the 20D treatment grew slowest. At least five tadpoles from each treatment, except 20D treatment, reached metamorphosis. Chirixalus idiootocus tadpoles in the 1D and 2D feeding treatments showed signs of growing, but tadpoles in the other four treatments did not grow at all. Only tadpoles in the 1D treatment reached metamorphosis. In another experiment, yolk digestion in the stomach of C. eiffingeri tadpoles was monitored. Yolk use was slow and egg yolk remained in the stomach for at least 8 days. Chirixalus idiootocus tadpoles could not tolerate long periods without food, probably because their digestive tract had a short clearance time and their stomach was incapable of long-term food storage. In contrast, between feedings, C. eiffingeri tadpoles seemed to mobilize food stored in their stomach, providing a continuous supply of nutrition to facilitate normal growth and development. These results and observations provide important insights into the maternal brood care of female C. eiffingeri .

Effect of Substituting De-hulled or Fermented Soybean Meal for Fish Meal in Diets on Growth of Hybrid Tilapia, Oreochromis niloticus×O. aureus

Two feeding experiments were conducted to evaluate the effects of replacing fish meal with de-hulled soybean meal (DSBM) and fermented soybean meal (FSBM) in diets on growth of juvenile hybrid tilapia. In experiment I, four isonitrogenous and isocaloric diets were formulated to contain 0-20% fish meal (or 57-31.6% DSBM) and fed to juvenile hybrid tilapia of 0.38 g initial body weight for 8 weeks. In experiment II, the diets containing 0-20% fish meal (51-28.3% FSBM) were fed to juvenile hybrid tilapia of 0.34 g. In both trials, the percent weight gain (WG) of the fish fed control diet (fish meal-free) was significantly (P＜0.05) lower than those fed diets containing fish meal. No difference was found in WG among fish fed diets containing fish meal. Although there was no significant (P＞0.05) difference among test groups, feed conversion and protein efficiency ratio followed similar trends as WG. Addition of encapsulated methionine did not improve the growth of fish fed diets containing no fish meal. Lowest feed consumption in control, indicating poor palatability from lacking the attraction of fish meal, could be the main reason for low WG of this group of fish.

The fatty acid composition of oophagous tadpoles (Chirixalus eiffingeri) fed conspecific or chicken egg yolk.

We compared the lipid content and fatty acid composition of (1) the egg yolk of three anuran species (Chirixalus eiffingeri, Rhacophorus moltrechti and Buergeria robustus) and chicken eggs; and (2) C. eiffingeri tadpoles fed conspecific eggs or chicken egg yolk. Anuran and chicken egg yolk contained more non-polar than polar lipids but the proportions varied among species. Chicken egg yolk contained low amounts of 22:5n-3 in the polar lipid fraction, and B. robustus eggs did not contain any n-3 or n-6 non-polar lipids. The specific variation of lipid contents and fatty acid composition may relate to the maternal diet and/or breeding biology. In C. eiffingeri tadpoles that fed chicken yolk or frog egg yolk, the dominant components of polar and non-polar lipids were 16:0, 18:0, 18:1, and 18:2n-6, or 20:4n-6 fatty acids. C. eiffingeri eggs contained more n-3 fatty acids (e.g. 18:3n-3 and 20:5n-3) than chicken egg yolk, and tadpoles fed conspecific eggs contained more of these fatty acids than tadpoles fed chicken egg yolk. The compositional differences in the fatty acids between C. eiffingeri tadpoles that fed frog egg or chicken egg yolk are the reflection of the variation in the dietary sources. Our results suggest a direct incorporation of fatty acids into the body without or minimal modification, which provide an important insight into the physiological aspects of cannibalism.

Fatty acid composition, sarcoplasmic reticular lipid oxidation, and immunity of hard clam (Meretrix lusoria) fed different dietary microalgae

Fatty acid profiles, activities of biomembrane lipid peroxidation, and immunity of a seawater clam (Meretrix lusoria) fed three species of dietary microalgae were investigated. Clams of a marketable size (25 g mean weight) were fed Tetraselmis chui, Chaetoceros muelleri, or Isochrysis galbana for 8 weeks. Fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in the polar lipid fractions of clams reflected those of the dietary algae species. Clams fed with T. chui and C. muelleri contained higher proportion of non-methylene interrupted (NMI) fatty acids than those fed I. galbana. Proportion of DHA in lipids of the clams fed with I. galbana was the highest among test groups. The NADH-dependent sarcoplasmic reticular lipid peroxidation activity of clams fed I. galbana was significantly greater (p < 0.05) than that of clams fed T. chui or C. muelleri. The hemocyte adhesion capacity of clams fed C. muelleri or I. galbana was significantly higher (p < 0.05) than that of clams fed T. chui. No significant differences (p ≥ 0.05) in total hemocyte count, phenoloxidase activity, clearance efficiency hemocyte and phagocytosis were detected among clams fed different microalgae.

Fatty Acid Composition of Copepods Fed with Different Diets

Research on the dietary requirements of marine fish larvae has evolved from considerations of optimal dietary levels of n-3 highly unsaturated fatty acids (HUFA) to considerations of optimal dietary ratios of the two principal HUFAs, 22:6 n-3 (DHA) and 20:5 n-3 (EPA), and optimal dietary levels and ratios of those essential fatty acids. In this study, we found the microalgae Isochrysis galbana have relatively high concentrations of 18-carbon, 16-carbon polyunsaturated fatty acid (PUFA), and especially DHA. The DHA/EPA ratio is approximately 27:1. Microalgae Tetraselmis chuii has high concentrations of 18-carbon, 16-carbon PUFA and EPA. The DHA/EPA ratio is approximately 6.4:1. Two species of copepods, Apocyclops royi and Pseudodiaptomus annandalei, which arc commonly found as live food used in fish or shrimp culture ponds in southern Taiwan. Both copepod can not survive on feeding alone on artificial animal protein (artificial fermented liquid, powdered clam feed. powdered eel feed), but can grow abundantly when they were fed with suitable phytoplankton with sufficient quantities of either I. galbana or T chuii. When fed with I. galbana, the EPA content of A. royi and P. annandalei were similar to the alga, but DHA increased by 9.55% and 7.55%, respectively. When fed with T. chuii, the EPA content of P. annandalei was similar to the alga, but A. royi decreased by 5.21%. However Dha, increased by 4.76% and 2.91%, respectively. The DHA/EPA ratio of copepod fed with either I. galbana or T. chuii are 61.4:1, 7.9:1, 45.0:1 and 0.6:1, respectively.