Roles of antioxidants on prolonged storage of avian spermatozoa in vivo and in vitro

This review focuses on natural and assisted prevention against lipid peroxidation in avian spermatozoa. The presence of high levels of n-6 polyunsaturated fatty acids (PUFAs) in the plasma membrane creates favorable conditions for the formation of peroxidative products, a major cause of membrane damage which may ultimately impair male fertility. However, a complex antioxidant system involving vitamin C, vitamin E and GSH is naturally present in avian semen. Coupled with a battery of enzymatic defenses (e.g., SOD, GSH-Px either Se- or non-Se-dependent), this system acts to prevent or restrict the formation and propagation of peroxides. The presence of specialized sites dedicated to prolonged sperm storage in avian females raises the question of durable protection of sperm membranes against peroxidation. Preliminary observations have revealed the presence of a specific antioxidant system at these sites in which vitamin C could exert a major role. From a practical standpoint, the extensive use of artificial insemination in poultry, along with the emergence in some species of workable techniques to cryopreserve spermatozoa, demand better control of peroxidation occurring in the plasma membrane of spermatozoa before or during storage. Dietary supplementation with vitamin E is effective in limiting lipid peroxidation of sperm plasma membranes, both in chickens and turkeys. In addition, organic Se with or without vitamin E stimulates Se-GSH-Px activity in seminal plasma. Preliminary observations in female chickens have also revealed the effectiveness of dietary supplementation with vitamin E, organic selenium or both to sustain fertility in aging flocks.     

Evidence for a species-specific barrier to sperm transport within the vagina of the chicken hen

Following their insemination into the vagina of chicken hens, turkey spermatozoa did not appear to reach the ovum within the upper magnum or infundibulum and were only occasionally found within the sperm storage tubules at the uterovaginal junction. Turkey spermatozoa were able to populate chicken uterovaginal sperm storage tubules as (or more) efficiently as fowl spermatozoa in uterovaginal junction tissue in vitro. They also populated uterovaginal junction sperm storage tubules in vivo after insemination directly into the uterovaginal region. Thus, a barrier to foreign spermatozoa appears to exist within the vagina of the chicken and not at the level of the uterovaginal junction sperm storage tubules. The nature of this barrier is not known; however it can be shown that while chicken and turkey spermatozoa have similar morphological features and motility characteristics, they have distinct surface antigenicity. Recognition of surface antigenicity by a localised immunological mechanism may be the basis of sperm selection within the hens vagina.     

The effect of dietary supplementation with blueberry, alpha-tocopherol or astaxanthin on oxidative stability of Arctic char (Salvelinus alpinus) semen

The objective was to determine the oxidative stability of Arctic char (Salvelinus alpinus) semen following dietary supplementation with lowbush blueberry (Vaccinium angustifolium) product, alpha-tocopherol, alpha-tocopherol+blueberry product, or alpha-tocopherol+astaxanthin. Sperm lipid peroxidation was initiated by challenging with ferrous sulphate/ascorbic acid (Fe(++)/Asc) at level of 0.04/0.2 mmol/L. Addition of blueberry, alpha-tocopherol, or both to char diets inhibited semen lipid peroxidation by: (a) decreasing the rate of sperm lipid peroxidation, an effect which was more pronounced with alpha-tocopherol treatments; and (b) increasing the antioxidant potential of seminal plasma, based on the lipid peroxidation process of sperm and an in vitro chicken brain tissue model. Dietary supplementation with astaxanthin and alpha-tocopherol had the same effect as the supplementation with alpha-tocopherol alone on inhibiting the lipid peroxidation process of sperm and chicken brain. Catalase-like activity increased significantly in sperm of fish fed alpha-tocopherol, blueberry, or both. There was a negative correlation (r= -0.397, P < 0.05) between catalase-like activity in sperm cells and the rate of sperm lipid peroxidation. Seminal plasma alpha-tocopherol levels increased significantly in fish supplemented with alpha-tocopherol alone or in combination with blueberry or astaxanthin. There were negative correlations between seminal plasma alpha-tocopherol levels and lipid peroxidation rates of sperm cells (r= -0.625, P < 0.01) and brain tissue (r= -0.606, P < 0.01). In conclusion, dietary supplementation of blueberry product or alpha-tocopherol inhibited lipid peroxidation in Arctic char semen. Further experiments are needed to test the effect of dietary blueberry and antioxidants on Arctic char semen quality during liquid and cryopreserved storage.     

Changes in the expression of estrogen receptor mRNA in the utero-vaginal junction containing sperm storage tubules in laying hens after repeated artificial insemination

The objective was to determine whether expression of estrogen receptor (ER) mRNA in the utero-vaginal junction (UVJ) of laying hens was altered after repeated artificial insemination (AI). Semi-quantitative RT-PCR was used to determine the expression of mRNA of the two types of receptor, ERalpha and ERbeta. Only ERalpha mRNA was expressed in all segments of the oviducts of both virgin and artificially inseminated birds, whereas ERbeta mRNA was expressed in ovarian follicles but not in the oviduct. The expression of ERalpha mRNA in the UVJ was significantly decreased after repeated AI, whereas that in the uterus was not significantly different between virgin and inseminated birds. Since estrogen may be involved in maintaining the sperm storage function of sperm storage tubules, the decreased expression of ERalpha mRNA in the UVJ after repeated AI may contribute to reduced fertility in these birds.     

Antioxidative activity and protective effect of probiotics against high-fat diet-induced sperm damage in rats

In this study, antioxidant capability and protective effect of probiotics on reproductive damage induced by diet oxidative stress were investigated. Thirty male Sprague-Dawley rats were randomly divided into three groups with 10 rats in each group. The control group consumed a normal standard diet (5% fat, w/w). The other two treatment groups were fed with a high-fat diet (20% fat, w/w), and a high-fat diet supplemented with 2% probiotics (w/w), respectively. At the end of the experimental period, that is, after 6 weeks, rats were killed. Activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), contents of nitric oxide (NO) free radical and malondialdehyde (MDA) in serum and sperm suspension were examined. Sperm parameters including sperm concentration, viability, motility and DNA integrity were analyzed. The results showed that high-fat diet could induce oxidative stress, shown as significant increases in lipid peroxidation, NO free radical, significant decrease in activities of SOD, GSH-Px, significant reduction in sperm concentration, viability and motility, and damage in sperm DNA (P < 0.05), compared with the control group. These alterations were significantly reversed in the probiotics-supplemented group and had no significant difference in antioxidant capability, lipid peroxidation and sperm parameters compared with the control group. The percentage of sperm with DNA damage was significantly lower than the high-fat diet group and still higher than the control group, which means that probiotics could attenuate sperm damage to some extent. The present results indicated that dietary probiotics had antioxidant activity and the protective effect against sperm damage induced by high-fat diet to some extent.     

Sperm storage in the oviduct of the American alligator

Oviducts of the American alligator (Alligator mississippiensis) were examined histologically for the presence of stored sperm. Two regions containing sperm were identified, one at the junction of the posterior uterus and the vagina (UVJ) and the other at the junction of the tube and isthmus (TIJ). In these areas, sperm were found in the lumina of oviductal glands. The glands in these areas of the oviduct are diffuse and shallow and appear to allow better access to sperm than glands located elsewhere. Histochemically, the glands of the UVJ reacted weakly for carbohydrates and proteins, whereas those of the TIJ reacted strongly for these same two components, secretions of which are associated with sperm storage structures in other reptiles. Sperm were not in contact with the glandular epithelium, and glands at the UVJ contained more sperm than those at the TIJ. Oviductal sperm storage was observed not only in recently mated females but in all females possessing uterine eggs as well as all females known to be associated with a nest. We conclude that female alligators are capable of storing sperm in their oviductal glands, but not from one year to the next.     

Effects of vitamin E supplementation in the extender on frozen-thawed bovine semen preservation

The maturing sperm cells discard the majority of their cytoplasm during the final stages of spermatogenesis and lose some of their defense enzymes. The purpose of this study was to investigate the effects of vitamin E supplementation on standard semen quality parameters and antioxidant activities of frozen-thawed bovine sperm. Vitamin E was added at concentrations of 0.5, 1.0, 1.5 and 2.0 mg/ml to bovine semen cryoprotective medium. The results showed that the sperm motility and VSL, STR values in the extender supplemented with 1.0 and 1.5 mg/ml of vitamin E, were significantly higher than that of other concentrations (P < 0.05). The percentages of acrosome-intact and membrane-intact sperm were significantly improved (P < 0.05) by supplementing with 1.5 mg/ml of vitamin E. In biochemical assays, the extender supplemented with vitamin E did not exhibit significant improvement in SOD (superoxide dismutase) levels, compared with the control (P > 0.05). Compared with other groups, CAT (catalase) levels were demonstrated to be greater with the supplementation of vitamin E at 1.0 and 1.5 mg/ml (P < 0.05). The extender supplemented with 1.5 mg/ml of vitamin E caused the highest levels of glutathione peroxidase (GSH-Px), compared with other groups (P < 0.05). The glutathione (GSH) activity was significantly higher with the supplementation of 0.5, 1.0 and 1.5 mg/ml of vitamin E, compared with 2.0 mg/ml in the vitamin E group and control (P < 0.05). Moreover, increasing the doses of vitamin E decreased sperm antioxidant activities, the extender supplemented with 2.0 mg/ml of vitamin E, caused the lowest levels of GSH-Px and GSH activities, compared with other treatment groups (P < 0.05). In conclusion, the beneficial effects of vitamin E noted in this study can be attributed to the antioxidant characteristics. Vitamin E supplementation in the extender reduced the lipid peroxidation potential and improved semen quality during freezing-thawing. More researches are needed to evaluate and understand the precise physiological role of vitamin E in reproduction.     

Effect of fish oil supplementation on plasma oxidant/antioxidant status in rats

The aim of this study was to investigate effect of dietary omega-3 fatty acid supplementation on the indices of in vivo lipid peroxidation and oxidant/antioxidant status of plasma in rats. The plasma thiobarbituric acid reactive substances (TBARS) and nitric oxide (NO) levels, and activities of xanthine oxidase (XO), superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) were studied in male Wistar Albino rats after ingestion of 0.4 g/kg fish oil (rich in omega-3 fatty acids, eicosapentaenoic acid and docosahexaenoic acid) for 30 days and compared to untreated control rats. The rats in the treated group had significantly higher SOD activity (P < 0.001), NO levels (P < 0.01) and decreased TBARS levels (P < 0.05) with respect to controls whereas GSH-Px and XO activities were not significantly different between the groups. None of the measured parameters had significant correlation with each other in both groups. We conclude that dietary supplementation of omega-3 fatty acids may enhance resistance to free radical attack and reduce lipid peroxidation. These results support the notion that omega-3 fatty acids may be effective dietary supplements in the management of various diseases in which oxidant/antioxidant defence mechanisms are decelerated.     

维生素C对凡纳滨对虾生长及抗病力的影响

以不同水平维生素C 2 磷酸酯 (添加量分别为 0、75、15 0、30 0和 6 0 0mg/kg)的饲料喂养凡纳滨对虾 10周 ,研究维生素C 2 磷酸酯对凡纳滨对虾生长及抗病力的影响。结果显示 :在养殖前 4周 ,饲料中添加维生素C 2 磷酸酯显著促进凡纳滨对虾的生长 ,然而对对虾的成活以及饲料利用不产生影响 (P >0 0 5 ) ;而到实验后期添加维生素C 2 磷酸酯不能促进凡纳滨对虾的生长 ,却显著提高凡纳滨对虾的成活率 (P <0 0 5 )。维生素C 2 磷酸酯对对虾体水分、脂肪、蛋白质和维生素C在肝胰脏中的积累量的影响显著 (P <0 0 5 ) ,对对虾体灰分影响不显著 (P >0 0 5 )。维生素C 2 磷酸酯对对虾血清中超氧化物歧化酶活力无显著影响 ,饲料中未添加维生素C或过量添加 (超过 30 0mg/kg饲料 )均导致血清中酚氧化酶活力、血细胞总数和溶菌酶活力的显著下降。以生长、成活和酚氧化酶活力为指标 ,饲料中维生素C 2 磷酸酯的适宜添加量为 15 0mg/kg。     

Specific features of in vivo and in vitro sperm storage in birds

This review focuses on some of the main features of sperm selection and storage in birds mainly on the basis of studies performed in poultry species, with emphasis on the initial selection of sperm at the female vagina level prior to migration towards the sperm storage tubules. Sperm originating from low-quality males or subjected to inappropriate in vitro storage conditions are rapidly discarded, resulting in impaired fertility in corresponding flocks. In the absence of accessible and appropriate technology for matching the 'storing' potential of sperm in the oviduct, conditions for prolonged sperm storage under a liquid (through the use of semen extenders) or a solid state (cryopreservation) have received only limited attention, despite their potential interest to facilitate male and female management in poultry flocks. Despite this, technology for short-term liquid storage is currently used in turkeys, guinea fowl and muscovy ducks and also in progress in chickens. In addition, technology for cryopreservation of avian semen has become available for some species (chicken, goose) to facilitate the management of genetic resources, including the preservation of rare and economically important breeds.     

Tissue-Specific antioxidant profiles and susceptibility to lipid peroxidation of the newly hatched chick

The hatching process is characterized by a range of adaptive changes, and a newly hatched chick is considered as an intermediate stage between prenatal and postnatal development. The aim of the present study was to evaluate the characteristic relationships between tissue-specific fatty acid composition and antioxidant protection in newly hatched chicks. Liver, yolk sac membrane, heart, kidney, lung, and four brain regions (cerebrum, cerebellum, stem, and optic lobes) were collected. Fatty acid composition of total lipids and phosphoglycerides, α-tocopherol, lutein, ascorbic acid, reduced glutathione, and the activities of Mn-and Cu,Zn-superoxide dismutase (SOD) and Se-dependent and non-Se-glutathione peroxidase (GSH-Px), and catalase (CAT) were determined. The levels of Fe, Cu, Zn, and Mn as well as tissue susceptibility to lipid peroxidation were also studied. The tissues of the newly hatched chick showed distinctive features in fatty acid profiles, antioxidant accumulation, and susceptibility to lipid peroxidation. The brain clearly displayed the greatest susceptibility to spontaneous and Fe-stimulated lipid peroxidation, was highly unsaturated and contained very low levels of vitamin E, no detectable carotenoids, low GSH-Px, and low CAT activity. At the same time, the brain was characterized by high ascorbic acid concentration and comparatively high SOD activity. It was suggested that in postnatal development, antioxidant enzymes presumably play the major role in antioxidant protection of the chick tissues.     

Antioxidative activity of naringin and lovastatin in high cholesterol-fed rabbits.

The consumption of a cholesterol-enriched diet increases the degree of lipid peroxidation, which is one of the early processes of atherosclerosis. The aim of this trial was to determine the antioxidative effects of the citrus bioflavonoid, naringin, a potent cholesterol-lowering agent, compared to the cholesterol-lowering drug, lovastatin, in rabbits fed a high cholesterol diet. Male rabbits were served a high-cholesterol (0.5%, w/w) diet or high-cholesterol diet supplemented with either naringin (0.5% cholesterol, 0.05% naringin, w/w) or lovastatin (0.5% cholesterol, 0.03% lovastatin, w/w) for 8 weeks to determine the plasma and hepatic lipid peroxide, plasma vitamin A and E levels, and hepatic hydrogen peroxide levels, along with the hepatic antioxidant enzyme activities and gene expressions. Only the lovastatin group showed significantly lower plasma and hepatic lipid peroxide levels compared to the control group. The naringin supplementation significantly increased the activities of both hepatic SOD and catalase by 33% and 20%, respectively, whereas the lovastatin supplementation only increased the catalase activity by 23% compared to control group. There was no difference in the GSH-Px activities between the various groups. Content of H2O2 in hepatic mitochondria was significantly lower in groups supplemented with lovastatin and naringin than in control group. However, there was no difference in cytosolic H2O2 content in liver between groups. The concentration of plasma vitamin E was significantly increased by the naringin supplementation. When comparing the antioxidant enzyme gene expression, the mRNA expression of SOD, catalase and GSH-Px was significantly up-regulated in the naringin-supplemented group. Accordingly, these results would appear to indicate that naringin, a citrus bioflavonoid, plays an important role in regulating antioxidative capacities by increasing the SOD and catalase activities, up-regulating the gene expressions of SOD, catalase, and GSH-Px, and protecting the plasma vitamin E. In contrast, lovastatin exhibited an inhibitory effect on the plasma and hepatic lipid peroxidation and increased the hepatic catalase activity in high-cholesterol fed rabbits.     

Liquid storage of turkey semen: changes in quality parameters, lipid composition and susceptibility to induced in vitro peroxidation in control, n-3 fatty acids and alpha-tocopherol rich spermatozoa

The study considered two major aims: (a) to measure the changes in quality parameters, lipid composition and antioxidant activity occurring in turkey spermatozoa during liquid storage; (b) to determine if the enrichment of sperm in n-3 fatty acids and alpha-tocopherol affect sperm survival during storage. Turkey breeders were fed a control diet or an Omega3 diet enriched with fish oil and alpha-tocopheryl-acetate. Ejaculates were pooled (5ejaculates/pool; 4pools/treatment) and stored in vitro for 48h at 4 degrees C. Viability, motility, susceptibility to induced peroxidation and alpha-tocopherol content were measured in spermatozoa; lipid and phospholipid fatty acid composition were measured in spermatozoa and seminal plasma. The proportion of motile and viable spermatozoa significantly decreased, and the proportion of dead spermatozoa significantly increased. The susceptibility of turkey spermatozoa to induced peroxidation also significantly increased during storage. The enrichment of turkey spermatozoa with n-3 long chain PUFA and vitamin E by dietary treatment did not prevent the negative effect of storage on sperm quality and sensitivity to induced in vitro peroxidation; however, it was efficient in partially prevent the increase of sperm death, therefore the proportion of dead spermatozoa was higher in control (37.4%) compared to treated spermatozoa (31.7%) after 48h liquid storage. Major changes were recorded in the lipid composition of turkey spermatozoa during liquid storage in both experimental dietary groups, whereas no significant changes were measured in seminal plasma. In spermatozoa, a great loss in the phospholipid and free cholesterol content was measured. Moreover, the loss in total sperm phospholipid was associated to a peculiar and selective decrease in the bounded fatty acids: saturates and monounsaturates were greatly reduced and polyunsaturates did not change. As a consequence, the polyunsaturated to saturated fatty acid ratio increased during 48h liquid storage. The observed changes in the lipid and phospholipid-bound fatty acid composition of turkey spermatozoa occurring during liquid storage might be related to different events and have been discussed.     

Effect of vitamin E and selenium supplementation of cockerel diets on glutathione peroxidase activity and lipid peroxidation susceptibility in sperm, testes, and liver

The phospholipids of avian spermatozoa are characterized by high proportions of arachidonic (20:4n-6) and docosatetraenoic (22:4n-6) fatty acids and are therefore sensitive to lipid peroxidation. α-Tocopherol and glutathione peroxidase [GSH-Px] are believed to be the primary components of the antioxidant system of the spermatozoa. The present study evaluates the effect of vitamin E and vitamin E plus Se supplementation of the cockerel diet on GSH-Px activity, vitamin E accumulation, and lipid peroxidation in the spermatozoa, testes, and liver. At the beginning of the experiment 75 Rhode Island Red cockerels were divided into five groups, kept in individual cages, and fed a wheat-barley-based ration balanced in all nutrients. Supplements fed to the different groups were as follows: vitamin E, 0, 20, 200, 20, and 200 mg/kg to groups 1–5, respectively, with groups 4 and 5 also receiving 0. 3 mg Se/kg. The vitamin E supplementation produced increased levels of α-tocopherol in semen, testes, and liver. The inclusion of the Se into the cock diet had a significant (P < 0.01) stimulating effect on GSH-Px activity in seminal plasma, spermatozoa, testes, and liver. The increased vitamin E concentration in the spermatozoa was associated with a reduction in their susceptibility to lipid peroxidation. Similarly, the increased GSH-Px activity provided enhanced protection against lipid peroxidation.     

Omega-3 fatty acids enhance mitochondrial superoxide dismutase activity in rat organs during post-natal development

The protection of the developing organism from oxidative damage is ensured by antioxidant defense systems to cope with reactive oxygen species (ROS), which in turn can be influenced by dietary polyunsaturated fatty acids (PUFAs). PUFAs in membrane phospholipids are substrates for ROS-induced peroxidation reactions. We investigated the effects of dietary supplementation with omega-3 PUFAs on lipid peroxidation and antioxidant enzyme activities in rat cerebrum, liver and uterus. Pups born from dams fed a diet low in omega-3 PUFAs were fed at weaning a diet supplying low α-linolenic acid (ALA), adequate ALA or enriched with eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA). Malondialdehyde (MDA), a biomarker of lipid peroxidation, and the activities of superoxide dismutase 1 (SOD1), SOD2, catalase (CAT) and glutathione peroxidase (GPX) were determined in the three target organs. Compared to low ALA feeding, supplementation with adequate ALA or with EPA + DHA did not affect the cerebrum MDA content but increased MDA content in liver. Uterine MDA was increased by the EPA + DHA diet. Supplementation with adequate ALA or EPA + DHA increased SOD2 activity in the liver and uterus, while only the DHA diet increased SOD2 activity in the cerebrum. SOD1, CAT and GPX activities were not altered by ALA or EPA + DHA supplementation. Our data suggest that increased SOD2 activity in organs of the growing female rats is a critical determinant in the tolerance to oxidative stress induced by feeding a diet supplemented with omega-3 PUFAs. This is may be a specific cellular antioxidant response to ROS production within the mitochondria.     

Ultrastructure of the reproductive system of the black swamp snake (Seminatrix pygaea): Part I. Evidence for oviducal sperm storage

Oviducal sperm storage in the viviparous (lecithotrophic) colubrid snake Seminatrix pygaea was studied by light and electron microscopy. Out of 17 adult snakes examined from May–October, sperm were found in the oviducts of only two specimens. In a preovulatory female sacrificed 14 May, sperm were found in the oviducal lumen and sperm storage tubules (SSTs) of the posterior infundibulum. In a nonvitellogenic female sacrificed 9 June, sperm were found in the lumen and glands of the posterior uterus and anterior vagina, indicating a recent mating. The glands in the posterior infundibulum and vagina were simple or compound tubular, whereas glands in the uterus always were simple tubular. The epithelium of the sperm storage glands was not modified from that lining the rest of the oviduct. The cuboidal or columnar epithelium consisted of alternating ciliated and secretory areas. The secretory product released into the lumen by a merocrine process contained mucoprotein. Lipid droplets also were numerous in the epithelium. Portions of sperm sometimes were embedded in the apical cytoplasm or in secretory material. A carrier matrix containing a mucoid substance, desquamated epithelium, lipids, membranous structures, and possibly phagocytes was found around sperm in the posterior uterus. J. Morphol. 241:1–18, 1999. © 1999 Wiley‐Liss, Inc.     

Quality and lipid composition of spermatozoa in rabbits fed DHA and vitamin E rich diets

The effects of fish oil (FO) and vitamin E (vE) dietary supplementation on semen quality, sperm susceptibility to lipid peroxidation, tocopherols content and fatty acid profiles were studied in rabbits. Fifty-two rabbit bucks randomly divided in four groups received a control diet and enriched diets containing either FO (1.5%, w/w), vE (200 mg/kg) or both. Semen volume, concentration, motility and viability were analysed at various time-points and the lipid composition was assessed on sperm cells. The phospholipid fatty acid profile was determined: n-6 PUFA were the major fatty acids found, with a proportion of 42%, whereas the n-3 PUFA accounted for nearly 1%, mainly represented by C22:6n-3 (docosahexaenoic acid, DHA). FO supplementation produced a seven-fold increase in the content of DHA in sperm phospholipids and a comprehensive rearrangement of the phospholipid fatty acid composition, while an unexpected negative effect of feeding high level of vE on the proportion of total PUFA was found. Despite the remarkable changes observed in sperm lipid composition, semen quality parameters were not affected by the dietary treatments and the interaction between the two dietary supplements had a significant effect only on sperm concentration. An increase in semen production by ageing and a concomitant rise in sperm susceptibility to in vitro peroxidation was found. α- and δ-tocopherol, present in rabbit sperm in similar amount, were not affected by dietary treatment. δ-tocopherol content had a significant linear negative regression with age and showed a significant negative correlation with the susceptibility to peroxidation values.     

Phospholipid Hydroperoxides and Lipid Peroxidation in Liver and Plasma of ODS Rats Supplemented with α-Tocopherol and Ascorbic Acid

Forty-five mutant male ODs rats, unable to synthesize ascorbic acid, were fed nine diets containing 5, 50 or 250 mg of vitamin E/kg diet and 150,300 or 900 mg of vitamin C/kg diet for 21 days. The concentrations of vitamins C and E increased in liver and plasma in relation to the level of these vitamins in the diet. Vitamin C dietary supplementation increased the plasma vitamin E content at low levels of vitamin E intake, supporting the concept of an in vivo synergism between both antioxidant vitamins. Vitamin C, at the dietary levels studied, did not affect the lipid peroxidation. Vitamin E decreased liver and plasma endogenous levels of thiobarbituric acid-reactive substances and liver sensitivity to non-enzymatic lipid peroxidation. This was confirmed by a highly specific assay of lipid hydroperoxides using high performance liquid chromatography with chemiluminescence detection. The hepatic concentration of both phosphatidylcholine and phosphatidylethanolamine hydroperoxides decreased as the vitamin E content of the diet increased. The results show for the first time the capacity of vitamin E to protect against peroxidation of major phospho-lipids in vivo under basal unstressed conditions.     

Effect of long-term supplementation with arachidonic or docosahexaenoic acids on sperm production in the broiler chicken

The possibility was investigated that dietary supplementation of the male chicken with long-chain polyunsaturated fatty acids of the n-6 and n-3 series may prevent the decrease in sperm output that normally occurs by 60 weeks of age. From 26 weeks of age, birds were raised on wheat-based diets supplemented with either maize oil (rich in linoleic acid, 18:2n-6), arasco oil (rich in arachidonic acid, 20:4n-6) or tuna orbital oil (rich in docosahexaenoic acid, 22:6n-3). The effects of the last two oils were investigated at two levels of vitamin E supplementation (40 and 200 mg kg(-1) feed). By 60 weeks of age, there was a small increase in the proportion of the main polyunsaturate of chicken sperm phospholipid, docosatetraenoic acid 22:4n-6, in chickens fed arasco oil diet compared with chickens given the maize oil diet, an effect that was potentiated at the higher dietary intake of vitamin E. Supplementation with tuna orbital oil significantly reduced the proportions of 20:4n-6 and 22:4n-6 in the sperm phospholipid and increased the proportion of 22:6n-3. The diet supplemented with tuna orbital oil and the lower level of vitamin E markedly depleted vitamin E from the tissues of the birds and decreased the concentration of vitamin E in the semen; these effects were largely prevented by the higher level of vitamin E in the diet. The susceptibility of semen to lipid peroxidation in vitro was increased in chickens fed arasco and tuna orbital oils with 40 mg vitamin E kg(-1) feed, but was reduced when 200 mg vitamin E kg(-1) feed was provided in the diet. The number of spermatozoa per ejaculate decreased by 50% between 26 weeks and 60 weeks of age in the birds fed the maize oil diet. This age-related decrease in the number of spermatozoa was almost completely prevented by feeding the birds with the oils enriched in either 20:4n-6 or 22:6n-3. Testis mass at 60 weeks of age was approximately 1.5 times greater in birds given of the arasco and tuna orbital oil diets compared with those given the maize oil diet.     

Antioxidant effect of vitamin E and glutathione on lipid peroxidation in boar semen plasma

The protective effect of vitamin E and reduced glutathione (GSH) against lipid peroxidation in boar semen plasma was studied. The lipid peroxidation, measured by the test for thiobarbituric acid reactive substances (TBARS), doubled in the presence of the lipid peroxidation Fe²⁺-sodium ascorbate-inducing system. The ascorbate-induced TBARS were inhibited by about 62% through the water-soluble vitamin E analog (TROLOX) and about 57% by GSH. In the in vivo experiments, 7 wk of oraldl-α-tocopherol acetate (1000 IU/d/animal) administration caused a significant fall in the level of the semen plasma TBARS, from 2.2±0.09 to 1.2±0.13 nmol MDA/mL. The semen plasma superoxide dismutase (SOD) and GSSG tended to increase with the time of vitamin E administration, but the increment did not reach a significant level by the seventh week. The vitamin E supplementation significantly increased the number of spermatozoa per 1 cm³ of ejaculate. The protective role of vitamin E and GSH with respect to boar semen against fatty acid peroxidation and a positive influence of vitamin E supplementation on semen quality have been evidenced.