Silymarin and Inflammation: Food for Thoughts

Inflammation is a vital defense mechanism, creating hostile conditions for pathogens, preventing the spread of tissue infection and repairing damaged tissues in humans and animals. However, when inflammation resolution is delayed or compromised as a result of its misregulation, the process proceeds from the acute phase to chronic inflammation, leading to the development of various chronic illnesses. It is proven that redox balance disturbances and oxidative stress are among major factors inducing NF-κB and leading to over-inflammation. Therefore, the anti-inflammatory properties of various natural antioxidants have been widely tested in various in vitro and in vivo systems. Accumulating evidence indicates that silymarin (SM) and its main constituent silibinin/silybin (SB) have great potential as an anti-inflammation agent. The main anti-inflammatory mechanism of SM/SB action is attributed to the inhibition of TLR4/NF-κB-mediated signaling pathways and the downregulated expression of pro-inflammatory mediators, including TNF-α, IL-1β, IL-6, IL-12, IL-23, CCL4, CXCL10, etc. Of note, in the same model systems, SM/SB was able to upregulate anti-inflammatory cytokines (IL-4, IL-10, IL-13, TGF-β, etc.) and lipid mediators involved in the resolution of inflammation. The inflammatory properties of SM/SB were clearly demonstrated in model systems based on immune (macrophages and monocytes) and non-immune (epithelial, skin, bone, connective tissue and cancer) cells. At the same time, the anti-inflammatory action of SM/SB was confirmed in a number of in vivo models, including toxicity models, nonalcoholic fatty liver disease, ischemia/reperfusion models, stress-induced injuries, ageing and exercising models, wound healing and many other relevant model systems. It seems likely that the anti-inflammatory activities of SM/SB are key elements on the health-promoting properties of these phytochemicals.

Probiotics as an alternative to antibiotics in modulating the intestinal microbiota and performance of broiler chickens

AIMS

Gut bacteria play an important role in poultry nutrition and the immune defense system. Changes in the intestinal microbiome affect the physiological state, metabolism, and innate immunity of poultry. The present study aimed to characterize age-related changes in the gastrointestinal tract microflora in broiler chickens, depending on supplementation of the diet with the in-feed antibiotic Stafac® 110 and a Bacillus subtilis strain-based probiotic.

METHODS AND RESULTS

In this regard, a comprehensive analysis of the taxonomic structure of the microbial community in the gastrointestinal tract (GIT) of broiler chickens was carried out using a molecular genetic technique of the terminal-restriction fragment length polymorphism analysis and taking into account age dynamics and feeding treatment. A beneficial effect on the microbiological composition and body weight of broilers was observed when using the antibiotic and probiotic in compound feeds. Different bacterial communities were revealed in the duodenum and cecum, and their positive impact on broiler growth was established. The results obtained shed light on the formation of GIT microflora of broiler chickens during the growing period and its changes in response to the use of the antibiotic and the probiotic.

CONCLUSIONS

We suggest that the implementation of the tested in-feed antibiotic and probiotic can be beneficial in regulating the intestinal microflora microbiological processes in the GIT and improving the feeding efficiency and productivity of broiler chickens.

Features of Fractal Conformity and Bioconsolidation in the Early Myogenesis Gene Expression and Their Relationship to the Genetic Diversity of Chicken Breeds

Elements of fractal analysis are widely used in scientific research, including several biological disciplines. In this study, we hypothesized that chicken breed biodiversity manifests not only at the phenotypic level, but also at the genetic-system level in terms of different profiles of fractal conformity and bioconsolidation in the early myogenesis gene expression. To demonstrate this effect, we developed two mathematical models that describe the fractal nature of the expression of seven key genes in the embryonic breast and thigh muscles in eight breeds of meat, dual purpose, egg and game types. In the first model, we produced breed-specific coefficients of gene expression conformity in each muscle type using the slopes of regression dependencies, as well as an integral myogenesis gene expression index (MGEI). Additionally, breed fractal dimensions and integral myogenesis gene expression fractal dimension index (MGEFDI) were determined. The second gene expression model was based on plotting fractal portraits and calculating indices of fractal bioconsolidation. The bioconsolidation index of myogenesis gene expression correlated with the chick growth rate and nitric oxide (NO) oxidation rate. The proposed fractal models were instrumental in interpreting the genetic diversity of chickens at the level of gene expression for early myogenesis, NO metabolism and the postnatal growth of chicks.

Antioxidant Defences and Redox Homeostasis in Animals

For many years reactive oxygen species (ROS) production in biological systems has been considered to be detrimental [...]

Taurine as a Natural Antioxidant: From Direct Antioxidant Effects to Protective Action in Various Toxicological Models

Natural antioxidants have received tremendous attention over the last 3 decades. At the same time, the attitude to free radicals is slowly changing, and their signalling role in adaptation to stress has recently received a lot of attention. Among many different antioxidants in the body, taurine (Tau), a sulphur-containing non-proteinogenic β-amino acid, is shown to have a special place as an important natural modulator of the antioxidant defence networks. Indeed, Tau is synthesised in most mammals and birds, and the Tau requirement is met by both synthesis and food/feed supply. From the analysis of recent data, it could be concluded that the direct antioxidant effect of Tau due to scavenging free radicals is limited and could be expected only in a few mammalian/avian tissues (e.g., heart and eye) with comparatively high (>15-20 mM) Tau concentrations. The stabilising effects of Tau on mitochondria, a prime site of free radical formation, are characterised and deserve more attention. Tau deficiency has been shown to compromise the electron transport chain in mitochondria and significantly increase free radical production. It seems likely that by maintaining the optimal Tau status of mitochondria, it is possible to control free radical production. Tau's antioxidant protective action is of great importance in various stress conditions in human life, and is related to commercial animal and poultry production. In various in vitro and in vivo toxicological models, Tau showed AO protective effects. The membrane-stabilizing effects, inhibiting effects on ROS-producing enzymes, as well as the indirect AO effects of Tau via redox balance maintenance associated with the modulation of various transcription factors (e.g., Nrf2 and NF-κB) and vitagenes could also contribute to its protective action in stress conditions, and thus deserve more attention.

Redox Homeostasis in Poultry: Regulatory Roles of NF-κB

Redox biology is a very quickly developing area of modern biological sciences, and roles of redox homeostasis in health and disease have recently received tremendous attention. There are a range of redox pairs in the cells/tissues responsible for redox homeostasis maintenance/regulation. In general, all redox elements are interconnected and regulated by various means, including antioxidant and vitagene networks. The redox status is responsible for maintenance of cell signaling and cell stress adaptation. Physiological roles of redox homeostasis maintenance in avian species, including poultry, have received limited attention and are poorly characterized. However, for the last 5 years, this topic attracted much attention, and a range of publications covered some related aspects. In fact, transcription factor Nrf2 was shown to be a master regulator of antioxidant defenses via activation of various vitagenes and other protective molecules to maintain redox homeostasis in cells/tissues. It was shown that Nrf2 is closely related to another transcription factor, namely, NF-κB, responsible for control of inflammation; however, its roles in poultry have not yet been characterized. Therefore, the aim of this review is to describe a current view on NF-κB functioning in poultry with a specific emphasis to its nutritional modulation under various stress conditions. In particular, on the one hand, it has been shown that, in many stress conditions in poultry, NF-κB activation can lead to increased synthesis of proinflammatory cytokines leading to systemic inflammation. On the other hand, there are a range of nutrients/supplements that can downregulate NF-κB and decrease the negative consequences of stress-related disturbances in redox homeostasis. In general, vitagene-NF-κB interactions in relation to redox balance homeostasis, immunity, and gut health in poultry production await further research.

Nutritional modulation of the antioxidant capacities in poultry: the case of selenium

Natural antioxidants play important roles in maintaining chicken health, productive and reproductive performance of breeders, layers, rearing birds, and growing broilers. There is a wide range of antioxidant molecules in the body: vitamin E, carotenoids, selenium, ascorbic acid, coenzyme Q, carnitine, taurine, antioxidant enzymes, etc. In the body all antioxidants work together to create the antioxidant network called "antioxidant systems" with Se being the "chief-executive." Analysis of the current data on selenium roles in antioxidant defenses in poultry clearly showed its modulatory effect at the level of breeders, developing embryos, newly hatched chicks, and postnatal chickens. On the one hand, Se is involved in the expression and synthesis of 25 selenoproteins, including GSH-Px, TrxR, and SepP. On the other hand, Se affects non-enzymatic (vitamin E, CoQ, and GSH) and enzymatic (SOD) antioxidant defense mechanisms helping build strong antioxidant defenses. Se efficiency depends on the level of supplementation and form of dietary Se, organic Se sources being more effective modulators of the antioxidant systems in poultry than sodium selenite. Moreover, Se levels in eggs from some wild avian species are close to those found in chicken eggs after 0.3 ppm organic Se supplementation and a search for most effective dietary form of organic Se is a priority in poultry nutrition. Antioxidant/prooxidant (redox) balance of the gut and the role/interactions of Se and microbiota in maintaining gut health would be a priority for future poultry research.

Revisiting Oxidative Stress and the Use of Organic Selenium in Dairy Cow Nutrition

In commercial animals production, productive stress can negatively impact health status and subsequent productive and reproductive performance. A great body of evidence has demonstrated that as a consequence of productive stress, an overproduction of free radicals, disturbance of redox balance/signaling, and oxidative stress were observed. There is a range of antioxidants that can be supplied with animal feed to help build and maintain the antioxidant defense system of the body responsible for prevention of the damaging effects of free radicals and the toxic products of their metabolism. Among feed-derived antioxidants, selenium (Se) was shown to have a special place as an essential part of 25 selenoproteins identified in animals. There is a comprehensive body of research in monogastric species that clearly shows that Se bioavailability within the diet is very much dependent on the form of the element used. Organic Se, in the form of selenomethionine (SeMet), has been reported to be a much more effective Se source when compared with mineral forms such as sodium selenite or selenate. It has been proposed that one of the main advantages of organic Se in pig and poultry nutrition is the non-specific incorporation of SeMet into general body proteins, thus forming an endogenous Se reserve that can be utilized during periods of stress for additional synthesis of selenoproteins. Responses in ruminant species to supplementary Se tend to be much more variable than those reported in monogastric species, and much of this variability may be a consequence of the different fates of Se forms in the rumen following ingestion. It is likely that the reducing conditions found in the rumen are responsible for the markedly lower assimilation of inorganic forms of Se, thus predisposing selenite-fed animals to potential Se inadequacy that may in turn compromise animal health and production. A growing body of evidence demonstrates that organic Se has a number of benefits, particularly in dairy and beef animals; these include improved Se and antioxidant status and better Se transfer via the placenta, colostrum, and milk to the newborn. However, there is a paucity in the data concerning molecular mechanisms of SeMet assimilation, metabolism and selenoprotein synthesis regulation in ruminant animals, and as such, further investigation is required.

Selenium in Poultry Nutrition: from Sodium Selenite to Organic Selenium Sources

Selenium (Se) is an essential element in poultry nutrition and its bio-efficacy depends on its chemical form. A growing body of research proves that organic forms of Se, mainly selenomethionine (SeMet), in poultry diets have a range of important advantages over traditional sodium selenite. In fact, the organic Se concept considers SeMet as a storage form of Se in the chicken body. As chickens are not able to synthesize SeMet, its provision through diet is a key strategy to fight commercially relevant stresses. Indeed, in stress conditions, when increased selenoprotein expression requires additional Se, while its provision via feed usually decreases due to a reduction in feed consumption, Se reserves in the body (mainly in the muscles) could help maintain an effective antioxidant defense and prevent detrimental consequences of stresses. The poultry industry is looking for the most effective sources of organic Se for commercial use. In this review, advantages and disadvantages of main organic Se sources for poultry (Se-yeast, SeMet, and OH-SeMet) are analyzed, and future directions for the development of new Se sources are identified.

Nano-Se Assimilation and Action in Poultry and Other Monogastric Animals: Is Gut Microbiota an Answer?

Recently, a comprehensive review paper devoted to roles of nano-Se in livestock and fish nutrition has been published in the Nanoscale Research Letters. The authors described in great details an issue related to nano-Se production and its possible applications in animal industry and medicine. However, molecular mechanisms of nano-Se action were not described and the question of how nano-Se is converted into active selenoproteins is not resolved. It seems likely that the gut microbiota can convert nano-Se into selenite, H₂Se or Se-phosphate with the following synthesis of selenoproteins. This possibility needs to be further studied in detail, and advantages and disadvantages of nano-Se as a source of Se in animal/poultry/fish nutrition await critical evaluations.

Antioxidant systems in chick embryo development. Part 1. Vitamin E, carotenoids and selenium

Chick viability is known to be an important factor determining profitability of the poultry industry. Chick embryo tissues contain a high proportion of highly polyunsaturated fatty acids in the lipid fraction and therefore need antioxidant defence. The antioxidant system of the developing embryo and newly hatched chick includes the antioxidant enzymes (superoxide dismutase, glutathione peroxidase, catalase), water-soluble antioxidants (ascorbic acid, taurine, carnitine, glutathione, etc.), fat-soluble antioxidants (vitamin E, carotenoids, coenzyme Q) as well as selenium (Se). In fact, the high levels of endogenous antioxidants within the egg and embryonic tissues can clearly serve as a major adaptive mechanism for the protection of the tissue during the oxidative stress experienced at hatching. It has been shown that among different nutrients in the maternal diet which could significantly affect chick embryo development and their viability in the early posthatch life, natural antioxidants have been suggested to play a central role. Our data indicate that increased supplementation of the maternal diet can substantially increase concentrations of vitamin E, carotenoids (especially canthaxanthin) and Se in developing chick tissues and significantly decrease susceptibility to lipid peroxidation being effective nutritional tools to deal with various commercial stresses in poultry production.

Selenium in pig nutrition and reproduction: boars and semen quality-a review

Selenium plays an important role in boar nutrition via participating in selenoprotein synthesis. It seems likely that selenoproteins are central for antioxidant system regulation in the body. Se-dependent enzyme glutathione peroxidase (GSH-Px) is the most studied selenoprotein in swine production. However, roles of other selenoproteins in boar semen production and maintenance of semen quality also need to be studied. Boar semen is characterised by a high proportion of easily oxidized long chain polyunsaturated fatty acids and requires an effective antioxidant defense. The requirement of swine for selenium varies depending on many environmental and other conditions and, in general, is considered to be 0.15 to 0.30 mg/kg feed. It seems likely that reproducing sows and boars are especially sensitive to Se deficiency, and meeting their requirements is an important challenge for pig nutritionists. In fact, in many countries there are legal limits as to how much Se may be included into the diet and this restricts flexibility in terms of addressing the Se needs of the developing and reproducing swine. The analysis of data of various boar trials with different Se sources indicates that in some cases when background Se levels were low, there were advantages of Se dietary supplementation. It is necessary to take into account that only an optimal Se status of animals is associated with the best antioxidant protection and could have positive effects on boar semen production and its quality. However, in many cases, background Se levels were not determined and therefore, it is difficult to judge if the basic diets were deficient in Se. It can also be suggested that, because of higher efficacy of assimilation from the diet, and possibilities of building Se reserves in the body, organic selenium in the form of selenomethionine (SeMet) provided by a range of products, including Se-Yeast and SeMet preparations is an important source of Se to better meet the needs of modern pig genotypes in commercial conditions of intensive pig production.

Polyphenol compounds in the chicken/animal diet: from the past to the future

Animal feed provides a range of antioxidants that help the body building an integrated antioxidant system responsible for a prevention of damaging effects of free radicals and products of their metabolism. Vitamin E is considered to be the main chain-breaking antioxidant located in the membranes and effectively protecting them against lipid peroxidation. Recently, various polyphenol compounds, especially flavonoids, have received substantial attention because of their antioxidant activities in various in vitro systems. However, it was shown that flavonoid compounds are poorly absorbed in the gut and their concentrations in target tissues are too low to perform an effective antioxidant defences. The aim of the present paper is to review existing evidence about possible roles of various plant extracts provided with the diet in animal/poultry nutrition with a specific emphasis to their antioxidant activities.

Changes in broiler chick tissue concentrations of lipid-soluble antioxidants immediately post-hatch

The antioxidant protection of the chicken (Gallus gallus) embryo during incubation and early postnatal development plays an important role in chick viability. To assess the antioxidant capacity of the newly hatched chick, we determined the concentrations of vitamin A, vitamin E, carotenoids and coenzyme Q₁₀ in the major tissues of chicks which had been held in an incubator for up to 36 h post-hatch. Concentrations of total carotenoids and free retinol and retinol esters in the tissues did not differ significantly over the 36 h period post-hatch (p>0.05). In contrast concentrations of vitamin E (α-tocopherol, γ-tocopherol, and α-tocotrienol and γ-tocotrienol) in various tissues (liver, heart, brain and leg muscle) decreased significantly in chicks that had been held in the incubator for 36 h when compared to younger chicks that were held for up to 18 h. Comparatively high concentrations of coenzyme Q₁₀ were detected in the yolk sac membrane, liver and heart, the concentrations being dependent on age of chicks, the highest value being recorded 18 h post-hatch. In most of the tissues studied, coenzyme Q₁₀ concentrations decreased substantially between 18 and 36 h post-hatch. This study demonstrated that there are tissue-specific changes in the concentrations of the major antioxidants (vitamin E and coenzyme Q₁₀) during the 36 h post-hatch.

Dietary fish and evening primrose oil with vitamin E effects on semen variables in cockerels

Our aim was to determine the effect of n-3 (2%, wt/wt, fish oil rich diet) and n-6 (2%, wt/wt, evening primrose oil rich diet) fatty acid dietary supplementation and their combination with two concentrations of vitamin E (40 vs 200 mg/kg) on semen variables and on fatty acid and vitamin E profiles of spermatozoa in broiler breeders at 32, 42 and 52 weeks of age. The inclusion of fish oil in the cockerel diets increased the docosahexaenoic acid proportion in the sperm phospholipid fraction, which was almost threefold higher compared to the other two groups irrespective of vitamin E supplementation. In contrast, an increase in the proportion of total n-6 polyunsaturates, mainly 22:4n-6, was observed in the evening primrose oil group compared to the control only when the dietary content of vitamin E was increased to 200 mg/kg. Sperm concentration was decreased in the fish and evening primrose oil groups if vitamin E was 40 mg/kg, but such an effect was prevented in the fish, not the evening primrose oil group, by increasing the vitamin E to 200 mg. The proportion of motile spermatozoa was improved by the increased supplementation of vitamin E in all oil treatments.

Maternal effects mediated by antioxidants and the evolution of carotenoid-based signals in birds

Bright yellow to red signals used in mate choice or intrasexual competition are based on carotenoid pigments that are hypothesized to be traded between physiological functions and coloration. These signals have recently been shown to be influenced by maternal effects. Indeed, yolk-derived carotenoids are essential for embryos to develop efficient carotenoid metabolism in posthatching life. Maternal effects facilitate adaptation to environmental variability and influence the evolution of phenotypic traits such as secondary sexual signals. Here we propose that maternal investment in yolk carotenoids promotes the evolution of carotenoid-based ornaments. We conducted a comparative analysis of lipid-soluble antioxidants (carotenoids and vitamins A and E) in the eggs of 112 species of bird. Species with large clutch sizes deposited higher yolk concentrations of the three antioxidants. There was a significant positive relationship between yolk carotenoids and the expression of male carotenoid-based signals, but not between yolk carotenoids and sexual dichromatism in these signals. These relationships were specific to carotenoids, as they were not found for vitamins A and E. This provides evidence consistent with the hypothesis that maternal effects mediated by yolk carotenoids play a role in the evolution of carotenoid-based signals as a response to sexual selection, likely based on organizational effects of carotenoids during embryo development.

Selenium in human and animal nutrition: resolved and unresolved issues. A partly historical treatise in commemoration of the fiftieth anniversary of the discovery of the biological essentiality of selenium, dedicated to the memory of Klaus Schwarz (1914-1978) on the occasion of the thirtieth anniversary of his death

Selenium (Se) is an essential trace element unevenly distributed on the Earth's crust with low selenium regions predominating. To prevent selenium-deficiency diseases in livestock, additions of selenium to animal feed are required and were approved for all species, but the chemical form of the element to be added was not specified. Presently, sodium selenite is still widely employed, although it is not a natural nutritional form of selenium. Its use creates ecological problems and affects human selenium nutriture in as much as the meat, milk, and eggs from animals maintained on selenite contain less selenium than from animals receiving it as selenomethionine, the chief natural nutritional form of the element present in grain crops grown in selenium-adequate regions, or from high-selenium yeast added to feedstock. Human dietary selenium intakes are sub-optimal in many countries but are considered to be adequate if they reach the currently adopted Recommended Dietary Allowances (RDAs). Their upward revision will be required if the health benefits of selenium are to be fully utilized.

Producing selenium-enriched eggs and meat to improve the selenium status of the general population

The role of selenium (Se) in human health and diseases has been discussed in detail in several recent reviews, with the main conclusion being that selenium deficiency is recognised as a global problem which urgently needs resolution. Since selenium content in plant-based food depends on its availability from soil, the level of this element in food and feeds varies among regions. In general, eggs and meat are considered to be good sources of selenium in human diet. When considering ways to improve human selenium intake, there are several potential options. These include direct supplementation, soil fertilisation and supplementation of food staples such as flour, and production of functional foods. Analysing recent publications related to functional food production, it is evident that selenium-enriched eggs can be used as an important delivery system of this trace mineral for humans. In particular, developments and commercialisation of organic forms of selenium have initiated a new era in the availability of selenium-enriched products. It has been shown that egg selenium content can easily be manipulated to give increased levels, especially when organic selenium is included in hens' diet at levels that provide 0.3-0.5 mg/kg selenium in the feed. As a result, technology for the production of eggs delivering approximately 50% (30-35 microg) of the human selenium RDA have been developed and successfully tested. Currently companies all over the world market selenium-enriched eggs including the UK, Ireland, Mexico, Columbia, Malaysia, Thailand, Australia, Turkey, Russia and the Ukraine. Prices for enriched eggs vary from country to country, typically being similar to free-range eggs. Selenium-enriched chicken, pork and beef can also be produced when using organic selenium in the diet of poultry and farm animals. The scientific, technological and other advantages and limitations of producing designer/modified eggs as functional foods are discussed in this review.

Protective effect of modified glucomannans and organic selenium against antioxidant depletion in the chicken liver due to T-2 toxin-contaminated feed consumption

The aim of this work was to assess the effect of T-2 toxin on the antioxidant status of the chicken and to study possible protective effects of modified glucomannan (Mycosorb) and organic selenium (Sel-Plex). Inclusion of T-2 toxin in the chickens' diet (8.1 mg/kg for 21 days) was associated with significant decreases in the concentrations of selenium (Se)(by 32.2%), alpha-tocopherol (by 41.4%), total carotenoids (by 56.5%), ascorbic acid (by 43.5%) and reduced glutathione (by 56.3%) in the liver, as well as a decrease in the hepatic activity of Se-dependent glutathione peroxidase (Se-GSH-Px) (by 36.8%). However, inclusion of modified glucomannans into the T-2 toxin-contaminated diet provided a partial protection against the detrimental effects of the mycotoxin on the antioxidant defences in the chicken liver. For example, the Se concentration in the liver was restored completely, although the Se-GSH-Px activity in the liver increased to only 81% of its control value. These protective effects of modified glucomannas were associated with a 45% reduction of lipid peroxidation in the liver in comparison to the effects of T-2 toxin alone. A combination of modified glucomannas with organic Se was shown to provide further protection against toxin-induced antioxidant depletion and lipid peroxidation in the chicken liver. Thus, the data clearly indicate a major protective effect of the mycotoxin-binder in combination with organic Se against the detrimental consequences of T-2 toxin-contaminated feed consumption by growing chickens.

Effects of carotenoids from lucerne, marigold and tomato on egg yolk pigmentation and carotenoid composition

1. The effects of various sources of natural carotenoids (Px alfalfa concentrate, tomato powder and marigold extract) as feed additives in quail diets on egg yolk pigmentation and carotenoid composition were investigated. 2. Adult Japanese quail were fed one of 5 different diets for 23 d: three diets each contained Px alfalfa concentrate (PX) or tomato powder (TP) or marigold extract (MG), one diet contained marigold extract and tomato powder (MG + TP) and a control diet (wheat/barley based) was low in carotenoid. All products were added at a rate of 2%, apart from marigold extract which was added at a rate of 0.2%. 3. Visual assessment of yolk colour (Roche colour fan) showed a stabilised yolk colour of 1.6, 7.7, 8.5, 8.8 and 10.6 for the control, PX, TP, MG and MG + TP treatments, respectively. 4. The total carotenoid concentration of the egg yolks were 2.2, 22.4, 4.1, 39.0 and 37.7 microg/g for the experimental groups fed the following diets: control, PX, TP, MG and MG + TP, respectively. Deposition of retinol, alpha-tocopherol and gamma-tocopherol in the egg yolk was unaffected by treatments. 5. Lutein was shown to be the major carotenoid in the egg yolk, comprising 1.65, 17.97, 2.03, 31.14 and 28.57 microg/g in control, PX, TP, MG and MG + TP, respectively. Inclusion of TP in the quail diet resulted in lycopene transfer to the egg. 6. It was concluded that, in comparison with the control group, there was an increase in the yolk concentrations of lutein, zeaxanthin, lycopene and beta-carotene in eggs produced by female quail fed diets supplemented with natural carotenoids.

Effect of organic selenium in quail diet on its accumulation in tissues and transfer to the progeny

1. The aim of the present study was to investigate the effects on the eggs and hatchlings (up to 2 weeks post-hatch) of feeding a relatively large amount of so-called organic selenium to breeder quail. 2. Two groups of quail (3 families in each group consisting of 4 females and 1 male) were formed at the beginning of their reproductive period. The quail were fed on a commercial maize-based diet containing 0.096 mg/kg feed-derived selenium (Se), supplemented with 0.2 mg/kg selenite (control group) or 0.5 mg/kg organic selenium in the form of Sel-Plex (Alltech Ltd, USA) for 6 months. Eggs were collected at 6 months of age and Se in the egg yolk, egg white and shell was analysed. Five quail at 1, 7 and 14 d post-hatch were killed to provide samples of liver, brain, breast and leg muscles for Se analysis. After egg collection for analysis and incubation, adult quail were killed and liver, kidney, lung, brain, breast and leg muscles were collected for Se analyses. 3. Inclusion of high doses (0.5 mg/kg) of organic Se in the quail diet was associated with a significant increase in Se concentration in all tissues studied of adult quail as well as in egg yolk, egg albumin and eggshell. 4. Increased Se concentration in the quail egg was associated with increased Se concentration in the liver, breast and leg muscles and brain of newly hatched quail. This difference was shown to be significant for 2 weeks post-hatch. Therefore, it has been suggested that the maternal effect of dietary selenium can be seen beyond the hatching time and more emphasis should be given to this effect in future. 5. It was shown that it is possible to produce Se-enriched quail meat and eggs by adding organic selenium to the diet.

An analysis of pre- and post-hatching maternal effects mediated by carotenoids in the blue tit

Maternal effects increase phenotypic plasticity in offspring traits and may therefore facilitate adaptation to environmental variability. Carotenoids have been hypothesized to mediate costs of reproduction in females as well as maternal effects. However, assessing potential transgenerational and population consequences of environmental availability of carotenoids requires a better understanding of mechanisms of maternal effects mediated by these antioxidant pigments. Manipulating dietary availability of carotenoids to egg-laying female blue tits and subsequently cross-fostering nestlings between female treatments allowed us to specifically investigate the relative importance of maternal effects through egg carotenoids and through post-hatching care mediated by antioxidants in females. Nestling body size and mass and plasma antioxidants were not significantly affected by pre- or post-hatching maternal effects mediated by antioxidants, although both types of maternal effects in interaction explained the variation in growth, as measured by wing length. Development of the ability to mount a cell-mediated immune response as well as its temporal dynamics was influenced by both pre- and post-hatching maternal effects, with an advantage to nestlings originating from, or reared by, carotenoid-supplemented females. In addition, nestlings reared by carotenoid-fed females had a lower blood sedimentation rate, indicating that they may have been less infected than nestlings from controls. Finally, prehatching maternal effects in interaction with nestling plasma carotenoid levels affected the development of carotenoid-based plumage. Maternal effects mediated by carotenoids may thus act as a proximate factor in development and phenotypic plasticity in traits associated with nestling fitness, such as immune response and ability to metabolize and use antioxidants, and ultimately participate in the evolution of phenotypic traits.

Selenium content in selected foods from the Greek market and estimation of the daily intake

The total selenium content of foods purchased from the North West part of Greece was determined using hydride generation atomic fluorescence spectroscopy. The results of this study were within the range from other countries. The overall mean average of selenium concentration of the foods examined, in decreasing order, was found in sesame seeds (783.1 ng g(-1)), fish (246 ng g(-1)), legumes (162.5 ng g(-1)), eggs (123 ng g(-1)), bread (91.9 ng g(-1)), meat (71.7 ng g(-1)), cheese (69.8 ng g(-1)), yoghurt (23.6 ng g(-1)), nuts (19.6 ng g(-1)), milk (15.4 ng g(-1)), vegetables (6.5 ng g(-1)) and fruits (3.4 ng g(-1)). Considering the average daily individual consumption of these foods by Greeks, the average daily dietary intake of selenium supplied by this source is 39.3 microg per capita.

Maternal organo-selenium compounds and polyunsaturated fatty acids affect progeny performance and levels of selenium and docosahexaenoic acid in the chick tissues

The effects of supplementing broiler breeder diets with polyunsaturated fatty acids (PUFA) and organo-Se compounds on the levels of Se and PUFA in chick tissues and on chick performance were assessed. Prepeak (23 wk) and peak (27 wk) production broiler breeders were fed 1 of 4 diets: a wheat-based commercial diet with soybean oil or fish oil but no added Se, and each diet with added Se as Sel-Plex (soybean oil + Se, fish oil + Se; Alltech Inc, Nicholasville, KY). The diets were designed to contain less than 0.1 mg of Se/kg and about 0.5 mg/kg for the nonsupplemented and the supplemented diets, respectively. As-hatched chicks from the 4 parental treatments were fed a nutritionally high quality diet (ME = 12.57 MJ/kg; CP = 228.7 g/kg) or a low quality diet (ME = 10.28 MJ/kg; CP = 182.8 g/kg), resulting in 8 dietary treatments. Performance was better and mortality lower in chicks from 27-wk-old breeders compared with those from 23-wk-old breeders. Fish oil in the maternal diet increased progeny mortality and reduced chick body mass at hatch. Body mass at 7 and 14 d posthatch was lower in chicks fed the low quality diet compared with chicks fed the high quality diet. At hatch, and for up to 14 d posthatch, chicks from hens fed diets high in PUFA had higher concentrations of docosahexaenoic acid (DHA) in the brain and liver compared with chicks hatched from hens fed diets low in PUFA. The DHA content of the tissues of chicks from breeders fed diets supplemented with Se was higher than that in chicks from breeders fed unsupplemented diets. Even after 14 d of being fed a diet with identical levels of Se, chicks hatched from parents fed diets high in Se had higher tissue Se concentrations than those hatched from parents fed diets low in Se. Supplementation of the maternal diet of chicks with organo-Se appears to enhance the DHA concentration of the chick brain, which may improve brain function.

Effects of Supplementing Broiler Breeder Diets with Organoselenium Compounds and Polyunsaturated Fatty Acids on Hatchability

The effects of supplementing broiler breeder diets with polyunsaturated fatty acids (PUFA) and organoselenium compounds on fertility, hatchability, and the weight of 1-d-old chicks was assessed. Prepeak (23 wk) and peak (27 wk) production breeders were fed 1 of 4 diets: a wheat-based commercial breeder diet with 55 g/kg of either soybean oil (SO) or fish oil (FO), but no added Se (only that originating from feed ingredients), and each diet with added Se as Sel-Plex (SO + Se, FO + Se). The diets were designed to contain <0.1 mg/kg of Se and about 0.5 mg/kg of Se for the nonsupplemented (no added Se) and the supplemented diets, respectively. The Se concentration of the eggshell of the hatching egg was measured. The concentration of Se, PUFA, and total lipid content of the brain and liver of the 1-d-old chick was determined. The number of fertile eggs increased, embryonic mortality decreased, and hatchability increased as hen age increased from 23 to 27 wk. The Se concentration in the eggshell and the brain and liver of 1-d-old chicks was higher in the high-Se treatments com pared with the concentration in the low-Se treatments. Fish oil inclusion in the breeder diet increased embryonic mortality in wk 3 of incubation and reduced both hatchability and 1-d-old chick weight in hens of both ages. The addition of Se to the FO diets ameliorated some of these adverse effects, because chicks hatched from eggs laid by 23-wk-old breeders of the FO + Se treatment were heavier than those receiving the FO treatment. The Se concentration in the brain and liver of chicks from the FO hens was higher than that in chicks from the SO hens. The concentration of docosahexaenoic fatty acid was higher in the liver of chicks from the SO + Se treatment compared with that of chicks from the SO treatment, indicating possible protective effects of Se. Hatchability was decreased by increased PUFA and was higher in 27-wk-old compared with 23-wk-old breeders.

Effect of organic selenium on turkey semen quality during liquid storage

The aim of the present study was to evaluate the effect of dietary organic selenium on the turkey semen during storage. Twenty males (BUT, Big 6, 40 weeks of age) were divided into control (n=10) and experimental group (n=10). The turkeys in the both groups were fed with a commercial diet containing 0.1 ppm Se in the form of sodium selenite. The experimental birds were additionally supplied with 0.3 ppm organic Se in the form Sel-Plex (Alltech, Inc.). After 30 days of feeding, the semen samples were collected twice a week for the 3 weeks of the study and diluted 1+1(v/v) with TUR-2 diluent, and stored in a water bath (+10 to 15 degrees C) for 6 h. The percentage of motile spermatozoa, the sperm viability (live/dead spermatozoa), total lipids, phospholipids and total cholesterol were assessed in fresh and stored semen. The fertilizing ability of semen was assessed by artificial insemination of 30 hens per group with dose containing 200x10(6) spermatozoa weekly. After 6 h of semen storage, the motility of spermatozoa decreased significantly in the control group (by 8.7 relative percent, P<0.05) and only by four relative percent (P>0.05) in experimental group reflecting a protective effect of dietary Se supplementation. The proportion of live spermatozoa was higher in fresh semen and significantly lower in stored semen. The positive effect of Se supplementation was observed on the lipid composition of stored semen: the concentration of the total lipids and phospholipids in the seminal plasma from control group significantly increased, while in the experimental group remained constant. Better semen integrity in the experimental group was associated with an improved fertilizing ability of spermatozoa: the fertility rate of stored spermatozoa in the control group was 88%, while in the experimental group was 90.5%.

Carotenoid availability in diet and phenotype of blue and great tit nestlings

Carotenoids are biologically active pigments of crucial importance for the development of avian embryos and nestlings. Thus parental ability to provide nestlings with a carotenoid-rich diet may enhance offspring fitness. However,very little is known about the possible effects of carotenoid availability in the diet on growing nestlings in natural populations. We experimentally manipulated dietary intake of carotenoids by nestlings of two closely related passerine species, the great tit Parus major and the blue tit Parus caeruleus, and measured nestling antioxidants, body condition,immunity and plumage colour. There was no detectable increase in plasma carotenoids after treatment in carotenoid-fed nestlings of either species despite regular supply of dietary carotenoids. However, in carotenoid-fed blue tit nestlings, plasma vitamin E concentration increased with plasma carotenoid concentration, while that was not the case for control nestlings. In both species, there was no significant effect of carotenoid supply on immune function. Carotenoid supplementation enhanced yellow feather colour in great tit nestlings only. In both species a strong effect of carotenoid supply was found on body condition with an increase in body mass for small carotenoid-fed nestlings compared to similarly sized control nestlings. Dietary availability of carotenoids may thus have important fitness consequences for tits. We hypothesise that the difference in effect of dietary carotenoids on the two species is due to relatively larger clutch size and higher growth rates of blue tits compared to great tits, leading to blue tit nestlings being more in need of carotenoids for antioxidant function than great tit nestlings.

Influences of carotenoid supplementation on the integrated antioxidant system of a free living endangered passerine, the hihi (Notiomystis cincta)

The integrated antioxidant system is recognised as an essential component of an organisms self maintenance. Our knowledge of this system, however, is largely restricted to species of economic importance. The health and productivity benefits these dietary based compounds provide make them increasingly relevant for study in wildlife ecology. The aim of this research was to identify numerous components of this integrated system in a free living and endangered passerine bird, the hihi. In addition experimental supplementation with carotenoids was used to investigate the modulatory interactions with other members of the antioxidant system. Our results identified lutein and zeaxanthin as the carotenoids utilised by hihi (82% and 17% of total carotenoids respectively in control samples of egg yolk, 84% and 16% of total carotenoids respectively in control samples of nestling plasma), and that vitamin E was represented by both alpha- and gamma-tocopherol. Retinol was also present, as was selenium in surprisingly high concentrations (599.64, 91.76, 377.72 ng/g fresh weight Se in control samples of yolk, albumin and plasma, respectively). Supplementation of lutein and zeaxanthin not only increased their presence in egg yolk (F(1,10)=14.285, P=0.005 and F(1,10)=9.606, P=0.015, respectively) and nestling plasma (F(1,19)=35.126, P<0.001 and F(1,19)=28.597, P<0001, respectively) but also led to increased selenium concentration in egg yolk (F(1,10)=7.213, P=0.028), increased retinol concentration in nestling plasma (F(1,19)=4.272, P=0.054) and decreased alpha-tocopherol concentration in nestling plasma (F(1,19)=5.122, P=0.037). These results provide detail of the antioxidant system in novel taxa and importantly highlight interaction between these various compounds. Given their increased application in productivity and health in agriculture and human medicine we highlight the potential application of this knowledge in wildlife ecology and conservation.

Interspecies variation in yolk selenium concentrations among eggs of free-living birds: The effect of phylogeny

Birds deposit the trace element selenium (Se) into their eggs because an adequate supply of this micronutrient is essential for embryonic development. Although there is considerable interest in egg Se with regard to topics as diverse as poultry nutrition and environmental pollution, data on the natural levels of Se in eggs of free-living avian species are currently very limited. To address this lack of information, we measured the yolk Se concentrations in eggs of 14 avian species collected in the wild. The concentrations (ng/g wet yolk) varied from 394 to 2238, with a mean value of 1040. Values (means+/-SD) for eggs from the UK, Canada and New Zealand were, respectively, 522+/-192 (3 species), 1194+/-584 (8 species) and 1147+/-200 (3 species). However, analysis by appropriate statistical models indicates that the effect of phylogenetic relatedness among these species is so significant that it removes any effect of geographical location. In particular, species belonging to the order Passeriformes displayed significantly higher yolk Se levels than Non-Passeriforme species. In marked contrast to the free-living species, our previously published data indicate that the Se concentration in egg yolk of the domestic chicken is only about 100 ng/g wet yolk when the birds are maintained on a basal commercial diet without supplementary Se. The results reveal an extensive interspecies variation in yolk Se (across a 6-fold range) for eggs collected from the wild. Nevertheless, the Se concentrations in the yolks of all the free-living species were far higher (4-21-fold) than that achieved in the yolk of the domestic chicken consuming a standard basal diet.

Embryonic development within carotenoid-enriched eggs influences the post-hatch carotenoid status of the chicken

Carotenoids in the diet of the laying hen are incorporated into the egg yolk and subsequently into the liver and other tissues of the chicken embryo. Since these pigments are known to provide a range of health benefits to a variety of animals, it is of interest to know whether the effects of maternally derived carotenoids are strictly limited to the embryonic period or if they persist in the progeny after hatching. The aim of this study is to compare the effectiveness of pre-hatch (from the hen's diet) with that of post-hatch (from the progeny's diet) supplementation with carotenoids on the carotenoid status of the chick during the first 4 weeks of post-hatch life. Hens were fed a control diet or a diet supplemented with a carotenoid-rich extract of alfalfa. Eggs from the supplemented hens contained up to 22 times more carotenoids than the controls. The concentration of carotenoids in the livers of chicks hatching from the enriched eggs was initially 29 times greater than in the control chicks. Hepatic carotenoid concentrations in chicks from enriched eggs maintained post-hatch on the control diet were sustained at higher values compared with chicks from control eggs that were fed post-hatch on the carotenoid-supplemented diet, for at least the first 7 days. However, by 14 days, the latter group had overtaken the former in terms of liver carotenoid levels. Thus, under these conditions, maternal effects predominate for at least the first week after hatching, whereas from 2 weeks onwards, the progeny's diet becomes the main determinant of its carotenoid status. Since the antioxidant and immunostimulatory roles of carotenoids are likely to be especially important during the immediate post-hatch period, maternal dietary intake of carotenoids may have important ramifications for the viability of the offspring.

The selenium intake of the female chicken influences the selenium status of her progeny

The primary purpose of this study is to determine the extent to which the effects of dietary supplementation of the female chicken with selenium (Se) continue into the next generation. An additional aim is to compare the relative effectiveness of pre-hatch (from the hen's diet) with that of post-hatch (from the progeny's diet) supplementation with Se on the Se status of the chick during the first 4 weeks of post-hatch life. Hens were maintained on control or Se-supplemented diets, respectively containing 0.027 and 0.419 mug Se/g of feed. The high-Se diet elevated the Se content of the hens' eggs by 7.1-fold. At hatch, the concentrations of Se in the liver, breast muscle and whole blood of the chicks originating from the high-Se parents were, respectively, 5.4-, 4.3- and 7.7-fold higher than the values in the chicks of the low-Se parents. When the offspring from the two parental groups were both maintained on the low-Se progeny diet, the tissue Se concentrations in chicks originating from the high-Se hens remained significantly higher for 3-4 weeks after hatching, compared with the values in chicks from the low-Se hens. Similarly, tissue glutathione peroxidase activity remained significantly higher in chicks from the high-Se hens for 2-4 weeks post-hatch. Thus, the effects of maternal Se supplementation persist in the progeny for several weeks after hatching. However, when chicks hatching from low-Se eggs were placed on a high Se diet, their tissue Se concentrations at 7 days of age were markedly higher than the values in chicks from high-Se eggs placed on the low-Se diet.

Tissue-specific distribution of carotenoids and vitamin E in tissues of newly hatched chicks from various avian species

The aim of this study was to evaluate carotenoid and vitamin E distribution in egg and tissues of newly hatched chicks from wild mallard (Anas platyrhynchos), game pheasant (Phasianus colchicus), free-range guinea fowl (Numida meleagris), hen (Gallus domesticus) and domestic duck (Anas platyrhynchos) and intensively housed hens. Carotenoid concentrations in the egg yolk of free-range guinea fowl, pheasant and wild mallard were similar (61.3-79.2 microg/g). Egg yolks from ducks and intensively housed hens were characterised by the lowest carotenoid concentration comprising 11.2-14.8 microg/g. However, carotenoid concentration in eggs from free-range ducks and hens was less than half of that in free-range guinea fowl or pheasant. Depending on carotenoid concentration in the livers of species studied could be placed in the following descending order: free living pheasant>free-range guinea fowl>>free-range hen>>intensively housed hen>wild mallard>>housed duck>free-range duck. The carotenoid concentrations in other tissues of free-range guinea fowl and pheasant were substantially higher than in the other species studied. Egg yolk of housed hens was characterised by the highest alpha- and gamma-tocopherol concentrations. In accordance with the alpha-tocopherol concentration in the egg yolk, the birds can be placed in the following descending order: intensively housed hen>wild mallard>free-living pheasant>free-range duck>free-range hen=free-range guinea fowl>housed duck. The main finding of this work is species- and tissue-specific differences in carotenoid and vitamin E distribution in the various avian species studied.

Lipid-soluble and water-soluble antioxidant activities of the avian intestinal mucosa at different sites along the intestinal tract

The antioxidant capacity of the avian intestinal mucosa is potentially important in protecting the gut wall from the harmful actions of reactive oxygen species originating from the diet, mucosal metabolism and the inflammatory response to enteric microbes. To assess this capacity, we determined the total lipid-soluble and water-soluble antioxidant activities of mucosal extracts, using tissue from different parts of the intestinal tract of the chicken. The lipid-soluble antioxidants, vitamin E and carotenoids, were also measured in the same samples. Total lipid-soluble antioxidant activity was highest in mucosa from the duodenum followed by the jejunum, with much lower activities in the ileum, ceca and colon. Total water-soluble antioxidant activity of the mucosa was at least an order of magnitude greater than the lipid-soluble activity under the assay conditions and did not differ significantly among the different parts of the intestinal tract. High concentrations of vitamin E were present in the mucosa of the duodenum and jejunum, with a trend to lower levels in the ileum and ceca, and significantly less in the colon. Similarly, the mucosa of the duodenum and jejunum contained the highest concentrations of carotenoids, with much lower levels in the ileum and colon. The different isoforms of vitamin E were absorbed from the digesta by the mucosa without any major selectivity. However, the liver was greatly enriched with alpha-tocopherol over the other isoforms, indicating a high degree of discrimination by this tissue. The results indicate major differences in the relative contributions of lipid- and water-soluble antioxidants in the mucosa along the different parts of the intestinal tract, most likely reflecting the sites of vitamin E and carotenoid absorption.

Effects of supplementing broiler breeder diets with organic selenium and polyunsaturated fatty acids on egg quality during storage

We assessed the effects of supplementation of broiler breeder diets with polyunsaturated fatty acids (PUFA) and organic Se on hatching egg quality during storage. Broiler breeders (n = 352) were fed 1 of 4 diets: SO (soybean oil with no added Se), SO with Se (SO+Se), fish oil (FO), or FO and Se (FO+Se). Eggs from prepeak (23 wk) and peak production (27 wk) breeders were stored for 14 d under typical (15 degrees C, 78% RH) conditions. Eggs were analyzed for albumen Haugh units (HU) and pH, shell characteristics, egg component weight, Se content, and fatty acid (FA) profile. The efficiency of transfer of Se into the egg was greater in low Se treatments compared with in high Se treatments. The majority of Se from the low Se treatments was deposited in the yolk, whereas in high Se treatments, the Se was deposited evenly in the yolk and albumen. In the low Se treatments, the Se content of yolk and albumen was lower than in the high Se treatments and decreased as age increased. Albumen HU decreased with increased storage, although high Se treatments had greater HU compared with low Se treatments. Eggs from the FO treatment were smaller with thinner eggshells compared with the SO treatment, but addition of Se to the FO diets ameliorated some of these effects. The egg yolk FA profile from the SO+Se treatment was altered compared with that from the SO treatment, perhaps due to interactions between dietary PUFA and Se-dependent enzyme systems. Hatching egg quality during storage was affected by dietary PUFA and Se content, as well as broiler breeder age.

Effects of carotenoid availability during laying on reproduction in the blue tit

Carotenoids are antioxidant pigments involved in several physiological processes and signalling in animals that cannot synthesise them and therefore must acquire them from food. We experimentally investigated the effects of carotenoid availability in the diet during egg laying on antioxidant deposition in egg yolk and the related effects on nestling condition, female body condition and parental investment in the blue tit (Parus caeruleus). Carotenoid supplementation of egg-laying females resulted in a significant increase in carotenoid concentration in egg yolk, but not in vitamin E or A concentration. There was no relationship between yellow plumage colour of adult females and carotenoid deposition in eggs, and no differential effect of feeding treatment depending on female colour. Nestlings from eggs laid by carotenoid supplemented females had longer tarsi, had faster development of the immune system as reflected by leukocyte concentration in blood, and grew brighter yellow feathers than nestlings from control females. However, nestlings from the two groups did not differ significantly in body mass, plasma antioxidants or plumage colour hue. At the time of chick rearing, carotenoid-fed females had increased plasma vitamin E levels compared to controls. However, females from the two treatment groups did not differ significantly in body condition or feeding rate. These results suggest that carotenoid availability is limiting during egg laying, and that females may have to balance the benefits of investing in egg quality against the potential costs of impairing their own future antioxidant protection. In addition, there may be considerable variation in carotenoid availability not only across seasons, but also among different stages of the breeding season.

Effects of maternal dietary supplementation with three sources of carotenoids on the retinyl esters of egg yolk and developing quail liver

The effects of supplementation of the maternal diet of quail with three natural sources of carotenoids (alfalfa nutrient concentrate (PX agrotrade mark), tomato powder and marigold extract) on the accumulation of retinol and retinyl esters in egg yolk and in the liver of the new hatchling and maternal were investigated. The present study showed that the vitamin A in quail egg yolk was present in 4 different forms, namely retinol (R 52-62%), retinyl linoleate (RL 9-11%), retinyl stearate (RS 4%), retinyl oleate (RO 11-15%) and retinyl palmitate (RP 13-22%). The retinyl ester profile of the liver of newly hatched quail (R 2-4%, RL 8-12%, RS 19-21%, RO 12-15%, RP 50-55%) differs from that of egg yolk but was similar to that of the liver of adult quail (R 1%, RL 5-6%, RS 21-28%, RO 9-12%, RP 54-63%). It has been shown that RO and RP concentrations in egg yolk and the liver of day old quail chick significantly increased as a result of carotenoid supplementation of the maternal diet.

Egg-laying capacity is limited by carotenoid pigment availability in wild gulls Larus fuscus

In birds, experimentally increased egg production can reduce maternal condition, parenting ability and survival, and the quality of the eggs themselves. Such costs probably reflect resource limitation, but the identity of the resource(s) in question remains unclear. Carotenoids are antioxidants and immunomodulants that birds can only obtain in their diet. Trade-offs in the allocation of limiting carotenoids between somatic maintenance and egg production could therefore be an important factor underlying reproductive costs. We show that in wild lesser black-backed gulls, Larus fuscus, dietary carotenoid availability (i) constrained the capacity to re-lay following clutch removal; and (ii) affected the relationship between yolk mass and egg mass. However, whether carotenoids are limiting for egg production directly, by stimulating the synthesis or antioxidant protection of yolk precursors, or indirectly via effects on maternal health, requires further study.