Effect Of Dietary Vitamin Research Articles

Effect of dietary supplementation with vitamin E on characteristics of vacuum-packed lamb

The effect of dietary vitamin E supplementation on lamb during vacuum-packed storage was studied. Thirty-six weaned male Manchego breed lambs were offered four dietary treatments (20, 270, 520 and 1020 mg vitamin E kg−1 feed). Lambs were fed the vitamin E-supplemented diet from 13 until 26 kg live weight. Pieces of M. longissimus dorsi were stored under vacuum at 2 ± 1 °C in the dark and meat quality was assessed after 5, 14 and 28 days of storage. Dietary supplementation significantly increased the α-tocopherol concentration in the muscle (P < 0.001). Initially, lipid oxidation, meat colour and bacterial load were similar in all groups. In meat of non-supplemented lambs the thiobarbituric acid reactive substance value increased throughout storage, whereas in meat of supplemented lambs it did not increase. Meat pigments and discolouration proportion were significantly affected by storage time (P < 0.001). The bacterial load was low initially, but after 28 days of storage it was close to 7 log10 colony-forming units (cfu) cm−2 and Enterobacteriaceae surpassed the limit of acceptability of 2.5 log10 cfu cm−2, making the lamb unsuitable for human consumption. Meat of supplemented lambs displayed less lipid oxidation than that of their non-supplemented counterparts, while meat colour and bacterial load were not affected by supplementation. Copyright © 2007 Society of Chemical Industry

Effects of dietary vitamin E and fat supplementation on pork quality1

The effects of dietary vitamin E (VE, alpha-tocopherol acetate) and fat supplementation on growth and carcass quality characteristics, oxidative stability of fresh and cooked pork patty in storage, fatty acid profiles of muscle and adipose tissue, and VE concentrations of plasma, muscle, and adipose tissue were studied. Six hundred pigs were allocated to 1 of 6 diets and fed for 63 d in a 3 x 2 factorial design. The dietary treatments included 3 fat levels (normal corn, high oil corn, high oil corn plus added beef tallow) and 2 levels of VE supplementation (40 IU/kg, normal VE supplementation; and 200 IU/kg, high VE supplementation). At 113 kg of BW, 54 pigs were slaughtered as a subsample to evaluate dietary effects on pork quality. Growth performance and meat quality characteristics did not differ (P > 0.05) among treatment groups. The high level of VE supplementation had a beneficial effect on the oxidative stability of pork as indicated by thiobarbituric acid reactive substance (TBARS) values. Lean tissue had lower (P < 0.05) TBARS in the group fed the high VE than in those fed the normal VE level. The TBARS values differed among storage periods (0 to 6 d) and also between fresh and cooked ground ham. Fat type did not significantly affect total saturated and unsaturated fatty acids proportions in the neutral and polar fraction of muscle. Adding VE acetate led to greater (P < 0.05) monounsaturated and total unsaturated fatty acid proportions in neutral lipids of muscle and adipose tissues. Increasing dietary levels of VE acetate increased the concentration of VE in plasma and muscle. These results indicate that dietary VE acetate supplementation increased (P < 0.05) lipid stability and the VE concentration of muscle.

Effect of dietary vitamin E supplementation and feeding period on pork quality1

Feeding increased levels of dietary vitamin E can inhibit lipid oxidation. The aim of this study was to investigate the effect of levels of dietary alpha-tocopherol acetate (VE) and feeding duration on meat quality and lipid oxidation. Eighty-one pigs were allocated to 1 of 3 diets containing 40, 200, or 400 IU of VE/kg of feed, and each diet group was divided into 3 feeding periods (3, 6, or 9 wk). Carcass characteristics and meat quality were evaluated. Oxidative stability of fresh and cooked pork patties and pork chops was determined after chilled or frozen storage. Increasing dietary concentrations of VE did not affect any growth performance parameter. Drip loss, however, decreased (P < 0.05) with increased dietary VE levels. Moreover, an increased duration of VE feeding improved (P < 0.05) pH and drip loss. Less lipid oxidation (P < 0.05) was detected in fresh ground pork from pigs fed greater concentrations of VE after 4 d of storage. A greater (P < 0.05) resistance to oxidation in cooked ground pork was observed in pigs fed 200 or 400 IU of VE/kg at 2 and 6 d of storage. Fresh and cooked pork patty oxidation decreased (P < 0.05) linearly as feeding duration increased from 3 to 9 wk. After 6 mo of freezer storage, lipid oxidation of pork chops from pigs fed 200 or 400 IU of VE/kg was lower (P < 0.05) than for pigs fed 40 IU of VE/kg. Likewise, lipid oxidation of pork chops of pigs fed VE for an extended period of time (6 wk) was lower (P < 0.05) after 9 mo of storage. Fatty acid profiles of neutral lipid fraction of the LM became more unsaturated (P < 0.05) with added VE to the feed. These results indicate an increased intake of dietary VE concentration, and prolonged feeding of VE can improve drip loss and reduce lipid oxidation in ground pork and pork chops. This study suggests that supplementation with 200 IU of VE/kg of feed for 6 wk before market is beneficial in improving lipid stability and pork quality.

Effect of dietary Vitamin E on the cloacal gland, foam and semen characteristics of male Japanese quail

This experiment was to investigate the effects of increasing the level of dietary Vitamin E (Vit. E) on cloacal gland size, foam production and semen characteristics of male Japanese quail ( Coturnix coturnix Japonica). One hundred and eighty male Japanese quail chicks (day old) were randomly distributed to three dietary treatments for a period of 25 weeks. Each treatment comprised of three replicates each containing 20 chicks. The basal diet contained 15 IU Vit. E/kg and the two experimental diets were supplemented with 150 and 300 IU Vit. E/kg (diets T 2 and T 3, respectively). DL α-tocopherol acetate was used as the source of Vit. E. All chicks were provided feed and water ad libitum. Foam characteristics, in terms of frequency of foam discharge (24 h), cloacal gland index and foam weight were significantly higher ( P < 0.05) in T 2 group. Body weight, testes weight (left and right) and plasma testosterone concentrations did not differ significantly. Semen characteristics (semen volume, sperm motility, % live sperm, % hatchability and sperm concentrations) did not differ significantly ( P > 0.05). Percentages of abnormal and dead spermatozoa were significantly ( P < 0.05) lower and fertility was higher ( P < 0.05) in the T 2 group. From this study, it can be concluded that moderate supplementation of dietary Vit. E may be beneficial for foam production, cloacal gland and improve the semen characteristics in male Japanese quail.

Effect of Dietary Vitamin E on Growth Performance and Immune Response of Breeder Chickens

The effect of dietary vitamin E supplementation on immune responses was studied in breeder chickens during the maturing period. In experiment 1, 17-week old female birds were fed corn-soybean meal based diets supplemented with either 0, 40, 80, 120, or 160 mg vitamin E (all-rac-α-tocopherol acetate)/kg diet for 19 weeks. In experiment 2, 23-week old male birds were fed the corn-soybean meal based diet supplemented with either 0, 20, 40, 80 or 160 mg vitamin E/kg diet for 8 weeks. The chickens were evaluated for growth performance, antibody titer to sheep red blood cell (SRBC), Newcastle disease virus (NDV), infectious bursal disease virus (IBDV) and infectious bronchitis virus (IBV), and skin response to phytohemagglutinin-P (PHA-P). The results showed that supplemental vitamin E improved body weigh gain of laying pullets during peak-laying period but had no significant effect on growth performance of cockerels. For cockerels, addition of 20 mg vitamin E/kg diet significantly enhanced (p<0.05) immune response to SRBC compared to those added with 0, 80 and 160 mg vitamin E/kg diet; addition of 20 mg vitamin E/kg diet had higher (p<0.01) antibody titer to IBDV than those added with 40-160 mg vitamin E/kg diet. No significant effects on immune response were observed in laying pullets fed supplemental vitamin E. The findings suggest that moderate supplementation of vitamin E may enhance immune responses to selective antigens in cockerels but excessive vitamin E may depress specific immune response. (Asian-Aust. J. Anim. Sci. 2006. Vol 19, No. 6 : 884-891)

Effect of Dietary Vitamin E Supplementation on Serum 慣-Tocopherol and Immune Status of Crossbred Calves

An experiment was conducted with twenty crossbred male calves (7-15 days old) divided into 4 different experimental groups on the basis of body weights to study the effect of vitamin E supplementation on the serum α-tocopherol concentration and immune response of the calves. All the calves were fed on milk and calf starter up to 13 weeks and afterwards, they were fed on concentrate mixture and oat hay up to 32 weeks of age. In addition, the calves in groups I, II, III and IV were supplemented with 0, 125, 250 and 500 IU feed grade DL-α-tocopheryl acetate, respectively. Blood samples were collected at 0 day and subsequently at 1, 2, 3, 4, 6 and 8 months of age to monitor the serum α-tocopherol concentration in crossbred calves. After 24 weeks of experimental feeding, 4 animals from each group were intramuscularly inoculated with single dose (3 ml) of Haemorrhagic septiceaemia (Pasteurella multocida P52 strain) oil adjuvant vaccine. The cumulative group mean serum α-tocopherol concentration (µg/100 ml) was 88.12, 210.11, 235.21 and 294.02 in-groups I, II, III and IV, respectively and differed significantly (p<0.001) among the four groups. Lymphocyte stimulation indices (LSI) did not differ among the groups significantly. The pooled mean ELISA antibody titer against Pasteurella multocida (P52 strain) was 788.02, 926.85, 1,214.00 and 1,109.51 for group I, II, III and IV, respectively, which indicated higher antibody titer in groups supplemented with vitamin E as compared to the control group. It may be concluded that vitamin E supplementation increased the α- tocopherol concentration in serum and dietary supplementation of vitamin E at higher level has a humoral immune enhancing effect against killed bacterial antigen. (Asian-Aust. J. Anim. Sci. 2006. Vol 19, No. 4 : 500-506)

Effect of Dietary Vitamin E and Selenium on DNA Damage in Fresh and Frozen Tissues

To determine whether deficiencies of dietary vitamin E and Se can elevate background DNA damage, rats were fed diets deficient in or supplemented with vitamin E (30 and 200 mg/kg diet) and Se (0.2 mg/kg diet) for 8 weeks. DNA damage was measured using the Comet (single-cell electrophoresis) assay and 8-oxodeoxyguanosine (8-oxo-dG) in liver, kidneys, and lymphocytes. We found that a deficiency of vitamin E and/or Se for 8 weeks did not significantly increase DNA damage in freshly isolated liver, kidneys, or lymphocytes. However, deficiency of vitamin E and/or Se for 8 weeks markedly increased DNA strand breaks in frozen kidney (-80 degrees C for 72 hours) and in lymphocytes incubated overnight at 37 degrees C, both of which were effectively prevented by supplementation of Se and vitamin E. However, vitamin E at 200 mg/kg did not afford more protection than it did at 30 mg/kg). Little or no significant increase in DNA damage was found in frozen livers. These results indicate that freezing or freeze-thawing of tissues may cause oxidative damage to DNA when the tissues are deficient in a major antioxidant, and that normal levels of vitamin E (30 mg/kg diet) and Se (0.2 mg/kg diet) are sufficient to prevent the damage. Thus, our results caution against the interpretation of DNA data obtained from frozen rat tissues or cells in animal studies with dietary vitamin E or Se deficiencies.

Effects of dietary vitamin A intake on acrosin- and plasminogen-activator activity of ram spermatozoa

Acrosin and plasminogen activators are proteolytic enzymes of ram spermatozoa that play an essential role in the induction of the acrosome reaction, as well as the binding of spermatozoa to the oocyte and their penetration through the layers that surround the oocyte. Since vitamin A can alter gene expression in various tissues, testis included, this study was undertaken to evaluate the possible effect of vitamin A intake on acrosin- and plasminogen-activator activity. During a 20-week experiment, 15 rams of the Greek breed Karagouniki, divided to three groups, received different amounts of vitamin A per os in retinyl acetate capsules (group A, controls, 12,500 iu/animal per day; group B, 50,000 iu/animal per day; group C, 0 iu/animal per day up to the 13th week, then 150,000 iu/animal per day until the end of the experiment). Acrosin- and plasminogen-activator activity were determined by spectrophotometric methods. Vitamin A was determined in blood plasma by HPLC. No statistical differences were detected regarding the body weight of the rams or the qualitative and quantitative parameters of their ejaculate throughout the whole experiment. No statistically significant alterations of enzyme activity were detected in group B. In group C, both enzyme activities started declining in week 9. Compared with controls, maximum reduction for acrosin was 49% on week 11 and for plasminogen activators 51% in week 14. Activities returned to normal rates after vitamin A re-supplementation. To date, the main result of vitamin A deficiency was known to be arrest of spermatogenesis and testicular degeneration. A new role for vitamin A may be suggested, since it can influence factors related to male reproductive ability before spermatogenesis is affected.

Effect of dietary vitamin C supplement on reproductive performance of aviary pheasants

The effects of three doses of vitamin C (100, 200 and 300 mg/kg) added to the feed of reproductive pheasants on egg production, egg fertility and parameters of hatchability were investigated. In experiments I (1999) and II (2000) birds were kept in outdoor aviaries. In 2000, air temperatures recorded on the farm during the experiment were high (25&amp;ndash;30&lt;sup&gt;o&lt;/sup&gt;C), differing considerably from those recorded in the preceding years. In experiment I no statistically significant differences were shown between the control pheasants and those supplemented with 100 and 200 mg/kg vitamin C in terms of egg production, egg fertility and parameters of hatchability. The poorest results were found in the group of birds receiving a feed supplemented with 300 mg/kg vitamin C. In experiment II, statistically higher egg production and egg fertility were noted, compared to the control group, in the groups supplemented with 100 and 200 mg/kg vitamin C. Compared to the control group, pheasants from these groups were also characterized by higher hatchability from set eggs (by approx. 15 percentage units) and fertilized eggs (by approx. 9 percentage units) and smaller number of unhatched chicks and dead embryos after day 10 of incubation. In experiment II, the beneficial effect of 100 and 200 mg supplements of vitamin C on the studied parameters could result from the soothing action of the vitamin on the effects of heat stress. The present results justify the prophylactic use of vitamin C supplement at 100 mg/kg feed in the nutrition of reproductive pheasants reared in aviaries. Under heat stress (high air temperatures) increasing the dose of this vitamin to 200&amp;nbsp;mg/kg feed seems beneficial. &amp;nbsp; &amp;nbsp;

Analysis of the variable effect of dietary vitamin E supplements on experimental atherosclerosis

Vitamin E inhibits processes thought to be important in the development of atherosclerosis but clinical trials to determine its effect on cardiovascular disease have given variable results, the majority being negative. The reasons for this are unclear. Animal trials can be better controlled and use more rigorous measures of lesion progression than human trials. The present study reviewed trials using rabbits and mice to determine whether they also are variable and, if so, to uncover methodological differences that may account for the different outcomes. A large number of trials examining the effect of vitamin E supplements on experimental atherosclerosis were identified. Using rigorous selection criteria, a well-defined group was selected for further investigation. Almost all the mice trials showed a significant effect of vitamin E, but only around one-third of the rabbit trials did so. When the rabbit trials were divided into those that did and those that did not observe significant effects, no single factor was found that could account for the dichotomy. However, when the percentage reduction in disease was considered, rather than the within-trial significance level, there were clear dose-dependent effects of vitamin E on disease severity in heritable hyperlipidaemic rabbits, and in genetically normal rabbits made hyperlipidaemic with cholesterol alone; the dose dependence was different in the two groups, the heritable hyperlipidaemic rabbits showing a near ten-fold lower sensitivity. The high doses required to affect experimental atherosclerosis may, if applicable to other species, help explain the absence of effects in many human trials.

Effects of dietary vitamin E and vitamin C supplementation on the level of α-tocopherol and L-ascorbic acid in muscle and on the antioxidative status and meat quality of pigs

In total thirty pigs (Slovak Meaty) defined by DNA based test as not susceptible to malignant hyperthermia (non-mutant on RYR1) were used in the experiment. Treatment consisted in supplementation of vitamin E (500 mg &amp;alpha;-tocopherol/kg diet as &amp;alpha;-tocopherol acetate) (group E) and the same doses of vitamin E plus vitamin C (200 mg L-ascorbic acid/kg diet) (group E + C) to finishing pigs for the last 30 days before slaughter. The higher dietary vitamin E level resulted in higher levels of &amp;alpha;-tocopherol in fresh (24 h), chill-stored (5 days, 4&amp;deg;C), chill-stored and cooked (80&amp;deg;C) and frozen meat (3 months, &amp;ndash;25&amp;deg;C), (P &amp;lt; 0.05). Higher dietary vitamin C resulted in higher levels L-ascorbic acid in fresh and chill-stored meat (P &amp;lt; 0.05) but no significant differences vs. control pigs were observed in cooked and frozen meats. Supplementation with vitamins E and C (group E + C) had positive effects on pH (45 min) (P = 0.06) and on drip loss (P &amp;lt; 0.05) values as compared to control group. The rate of oxidation (malondialdehyde-MDA production) by stimulation with Fe&lt;sup&gt;2+&lt;/sup&gt;/ascorbate (incubation of muscle LD for 0 and 30 min) was higher in control group as compared to both experimental groups (P &amp;lt; 0.05). Positive effects of vitamin E on oxidative stability measured as thiobarbituric acid reactive substances (TBARS, MDA) were observed mainly in chill-stored meat (P &amp;lt; 0.05). Using TBARS method, no additional effect of vitamin C on oxidative stability of fresh, chill-stored, cooked and frozen meat was found. In conclusion, supplementation of the combination of vitamin E (500 mg &amp;alpha;-tocopherol/kg diet) and vitamin C (200 mg L-ascorbic acid/kg diet) for 30 days before slaughter improved meat quality values (drip loss, pH), however, it seems to depend on the genetic background of animals (occurrence of mutation on RYR1). Oxidative stability of meat lipids measured as TBARS value can be improved by vitamin E supplementation to feed. &amp;nbsp;

Effects of Dietary Vitamins C and E on Egg Shell Quality of Broiler Breeder Hens Exposed to Heat Stress

A feeding trial was conducted to determine whether dietary vitamin C (200 mg/kg) and vitamin E (250 mg/kg) prevent any drops in egg shell quality under heat stress in broiler breeder hens. One hundred and sixty molted Ross broiler breeders were housed randomly in an individual cage at 83 weeks of age. Four dietary treatments with forty hens and four replications per treatment were control (no additional vitamins), vitamin C-, or vitamin E-supplemented and combined supplementation of the two vitamins. After a ten- day-adaptation period at 25°C, the ambient temperature was kept at 32°C for a three-week-testing period. Egg production dropped dramatically over week but it did not show a significant change among treatments (p<0.05). However, egg quality parameters such as egg weight, specific gravity, shell thickness, SWUSA, puncture force and shell breaking strength from the birds fed the diet with the combined vitamins C and E were significantly improved over those of the control group during the heat stress period (p<0.05). The hens fed the vitamin C diet improved tibia breaking strength (37.16 kg), statistically higher than the birds fed the control and the vitamin E diets (p<0.05). The hens fed the control diet showed higher serum corticosterone levels, a mean of 5.97 ng/ml, than those of the other treatments (p<0.05). The heat stress resulted in elevated heterophils and decreased lymphocytes in serum, increasing the H/L ratios for all the treatments. However, the increases in H/L ratios were alleviated by feeding the diets containing vitamin C alone or together with vitamin E, although there were no significant differences in the ratio between the two groups (p<0.05). In conclusion, vitamins C (200 mg/kg) and/or E (250 mg/kg) supplemented to the diets for broiler breeder hens could prevent drops in egg shell quality and tibia bone strength under highly stressful environmental temperatures. (Asian-Aust. J. Anim. Sci. 2005. Vol 18, No. 4 : 545-551)

Effect of dietary supplementation of vitamin E on characteristics of lamb meat packed under modified atmosphere

The effect of dietary vitamin E supplementation on modified-atmosphere packed lamb meat during storage was studied. Thirty-six weaned male Manchego breed lambs were fed diets supplemented with three different vitamin E concentrations (0, 250, 500 and 1000 mg/kg feed) for an average of 37 days, in the 13–26 kg live weight growth range. Slices of m. longissimus dorsi were packaged under modified atmosphere (70% O 2 and 30% CO 2), stored at 2 ± 1 °C in darkness for 14 and 28 days. Meat quality parameters after both storage periods were assessed. Dietary vitamin E supplementation significantly increased α-tocopherol concentration in muscle. Initially, lipid oxidation (TBARS), meat colour and bacterial load were similar in all groups. Lipid and colour oxidation of meat increased significantly ( P < 0.001) throughout storage. The increase was greater in non-supplemented lambs than in supplemented ones. The bacterial counts after 28 days of storage reached the limit for microbiological shelf life (7 log 10cfu/cm 2). Dietary vitamin E supplementation increased the shelf life of meat packaged under modified atmosphere to 14 days. TBARS, pigment oxidation and bacterial load were inside the acceptable limit. The meat maintained its quality for 28 days of storage only when lambs were fed with the 1000 mg/kg dietary supplement, though the bacterial load was at the limit of acceptability.

The effect of dietary vitamin E and fatty acid supplementation of pregnant and lactating ewes on placental and mammary transfer of vitamin E to the lamb

The present study investigated the effect of maternal vitamin E and fatty acid supplementation on lamb antioxidant status. Forty-eight ewes were fed one of four concentrate diets supplemented with a basal (50 mg/kg) or supranutritional (500 mg/kg) level of vitamin E plus a source of either saturated fat (Megalac; Volac Ltd, Royston, Hertfordshire, UK) or long-chain PUFA (fish oil) from 6 weeks prepartum until 4 weeks postpartum. Blood samples were taken from ewes and lambs at intervals throughout the experiment and, at parturition, muscle, brain and blood samples were obtained from twelve lambs (three per treatment). Colostrum and milk samples were obtained at 12 h and 21 d after parturition, respectively. Supranutritional vitamin E supplementation of the ewe significantly increased concentrations of vitamin E in neonatal lamb tissues although plasma concentrations were undetectable. A significant increase in lamb birth weight resulted from increasing the dietary vitamin E supply to the ewe. Furthermore, maternal plasma, colostrum and milk vitamin E concentrations were increased by vitamin E supplementation, as were lamb plasma concentrations at 14 d of age. Neonatal vitamin E status was not significantly affected by fat source although plasma vitamin E concentrations in both ewes and suckling lambs were reduced by fish oil supplementation of the ewe. Fish oil supplementation reduced vitamin E concentrations in colostrum and milk and the activity of glutathione peroxidase in suckling lambs. The data suggest that the vitamin E status of the neonatal and suckling lamb may be manipulated by vitamin E supplementation of the ewe during pregnancy and lactation.

Dietary Vitamin E Does Not Inhibit the Promotion of Liver Carcinogenesis by Polychlorinated Biphenyls in Rats

In this study, the effect of dietary vitamin E on the hepatic tumor-promoting activity of PCB-77 and PCB-153 in female Sprague-Dawley rats (175-200 g) was investigated. One week after diethylnitrosamine injection, rats were fed purified diets containing 10, 50, or 250 mg/kg vitamin E in the form of alpha-tocopheryl acetate. Starting 1 wk later, we injected rats i.p. with vehicle (corn oil) or PCB-77 or PCB-153 (300 mumol/kg) every 14 d for 4 injections. All rats were killed 10 d after the last PCB injection. The number and volume of placental glutathione S-transferase (PGST)-positive foci were increased by PCB-77 but not by PCB-153. Vitamin E did not affect the induction of PGST-positive foci. PCB-77, but not PCB-153, increased hepatic NF-kappaB activity. In conclusion, dietary vitamin E supplementation does not protect against the induction of altered hepatic focal lesions by PCBs.

Dietary vitamin E reduces labile iron in rat tissues

Previous studies have shown that dietary vitamin E reduced generation and/or levels of superoxide. As superoxide has potential to release iron from its transport and storage proteins, and labile or available form of iron is capable of catalyzing the formation of reactive hydroxyl radicals, the effect of dietary vitamin E on labile iron pool was studied in rats. One-month-old Sprague-Dawley male and female rats were fed a basal vitamin E-deficient diet supplemented with 0, 20, 200, or 2,000 IU vitamin E/kg diet for 90 days. The levels of labile iron were measured in the liver, kidney, spleen, heart and skeletal muscle. Additionally, the levels of lipid peroxidation products were measured. The results showed that, except for labile iron in the heart of male rats, dietary vitamin E dose dependently reduced the levels of labile iron and lipid peroxidation products in all tissues of male and female rats. The findings suggest that dietary vitamin E may protect against oxidative tissue damage by reducing the generation and/or level of superoxide, which in turn attenuates the release of iron from its protein complexes.

Effects of Dietary Vitamin A on Juvenile Red Sea Bream Chrysophrys major

AbstractA 55‐d feeding experiment was conducted to evaluate the effects of dietary vitamin A on growth of juvenile red sea bream Chrysophrys major. Nine semi‐purified diets with supplemental retinol palmitate at levels of 0, 300, 600, 1,500, 3,000, 4,500, 6,000, 15,000 and 30,000 retinol eq/kg diet, were fed twice daily to triplicate groups of 10 juveniles per tank with an initial weight of 1.178 ± 0.001 g. Weight gain and specific growth rate increased with the increase of supplemental retinol palmitate in the diet up to a level of 6,000 retinol eq/kg diet, beyond which those indices tended to decrease slightly or to plateau. Significantly lower weight gain and specific growth rate were observed in fish fed with 0 and 300 retinol eq/kg diet. No significant differences were found in survival rates among the different levels of supplementation. The crude protein, lipid, moisture and ash contents in the whole body were not affected by the different vitamin A supplemental levels. Besides the reduced growth, fish fed with low levels of vitamin A supplement showed no other signs of deficiency. No hypervitaminosis A symptoms were observed in fish fed on high levels of supplementation. Fish fed on diets with 0 and 300 retinol eq/kg diet showed a significantly lower content of vitamin A (as a total retinol) in the liver than those in groups fed with higher levels of supplementation. Vitamin A was stored in the liver mainly as retinyl esters. Total retinal content of the eye showed no significant differences among the treatments; however, fish fed with 0 and 300 retinol eq/kg of diet had slightly higher concentrations. According to the results of the mean weight gain, specific growth rate and liver retinol content, the requirement of dietary vitamin A for juvenile red sea bream was estimated to be between 1,500 and 6,000 retinol eq/kg.

Effects of dietary vitamins C and E on alternative complement activity, hematology, tissue composition, vitamin concentrations and response to heat stress in juvenile golden shiner ( Notemigonus crysoleucas)

The objective of this study was to characterize the response of golden shiner fed one of eight purified diets with either 0 or 38 mg α-tocopherol (α-T) kg −1 and one of four levels of ascorbic acid (AA) (23, 43, 98, or 222 mg kg −1 diet) in a 2×4 factorial design. Growth, survival, signs of vitamin E deficiency, and immune and stress responses were monitored in groups of 30 golden shiners (mean average initial weight=0.79 g) fed the diets to apparent satiation twice daily in triplicate aquaria for 14–19 weeks. The average individual weight gain was not affected by dietary α-T concentrations at 14 weeks, but the survival of fish fed the α-T-unsupplemented diets was lower than that of fish fed the α-T-supplemented diets. After 10 weeks, fish fed the α-T-unsupplemented diets began to show vitamin-E-deficiency signs such as increased prevalence of fish with darkened skin. After 17 weeks the deficient fish had lower α-T concentrations in viscera, lower whole-body crude protein, total lipid, dry matter, hematocrit, hemoglobin, lymphocyte (%), alternative complement activity (ACH50), and survival after exposure to stressful water temperatures (36–37 °C) than those fed the α-T-supplemented diets. A sparing effect of vitamin E on vitamin C was evident. Elevated dietary vitamin C reduced the incidence and severity of vitamin E deficiency signs in a dose-dependent manner. The interactive effect of vitamins C and E on ACH50 activity and percentage of thrombocytes was also significant. Regardless of vitamin E levels, different vitamin C levels did not influence the α-T concentration in viscera and other interactions between vitamins C and E were not evident.

Effects of dietary vitamin C on growth and immune response of Japanese seabass, Lateolabrax japonicus

Studies were conducted to investigate the effects of dietary ascorbic acid on growth, survival, tissue concentration and immune response of Japanese seabass (initial average weight 6.26±0.10 g). Seven practical diets were formulated to contain 0.0, 12.2, 23.8, 47.6, 89.7, 188.5 and 489.0 mg ascorbic acid equivalent kg −1 diet, supplied as l-ascorbyl-2-polyphosphate (LAPP). Each diet was fed to triplicate groups of fish in seawater floating cages (1.5×1.5×2.0 m), and each cage was stocked with 80 fish. Fish were fed twice daily (06:30 and 16:30) to apparent satiation for 8 weeks. The water temperature fluctuated from 26.5 to 32.5 °C, salinity from 32‰ to 36‰ and dissolved oxygen approximately 7 mg l −1 during the experimental period. The optimum growth was obtained in diets with equal to or more than 47.6 mg ascorbic acid kg −1 diet. The ascorbic acid concentrations in liver and muscle correlated positively with those in diets. The vitamin C requirements were estimated to be 53.5 mg kg −1 based on growth performance, 93.4 mg kg −1 based on liver concentration of ascorbic acid and 207.2 mg kg −1 based on muscle concentration of ascorbic acid. The activities of lysozyme and alternative complement pathway in serum increased with the increase of dietary ascorbic acid. When dietary ascorbic acid reached 489.0 mg kg −1, these parameters were significantly higher than those of all other treatments.

The effects of dietary vitamin E and selenium deficiencies on plasma thyroid and thymic hormone concentrations in the chicken

Beginning at hatching, male Cornell K strain single comb white leghorn chickens were fed a basal diet, with or without vitamin E (100 IU/kg) and/or selenium (Se, 0.2 ppm). After 3 weeks of treatment, animals fed either the Se-deficient or basal diet had significantly reduced plasma Se-dependent glutathione peroxidase activities when compared to those fed a vitamin E and Se-supplemented diet. Similarly, animals fed the vitamin E-deficient or basal diet had significantly reduced plasma α-tocopherol levels. The effect of these treatments on plasma concentrations of thyroid hormones (T 3/T 4), growth hormone (GH), and thymic hormone (thymulin) was determined using radioimmunoassay and ELISA. A deficiency in Se, but not in vitamin E, resulted in an increase in plasma T 4 concentrations while plasma T 3 concentrations were decreased. Plasma GH levels showed some fluctuation as a result of the dietary treatments but there was no significant correlation between plasma GH levels and any of the other variables. A significant decrease in plasma thymulin levels was observed in Se-deficient birds compared to those receiving adequate Se in the diet. A vitamin E deficiency had no measurable effect on plasma thymulin levels. From these studies, we conclude that plasma thymulin concentrations directly correlate with plasma T 3 concentrations which are negatively affected by a Se deficiency.