Peter F. Surai

Carotenoids and egg quality in the lesser black-backed gull Larus fuscus: a supplemental feeding study of maternal effects

Egg quality is a phenotype of, and can profoundly influence fitness in, both mother and offspring. However, the physiological mechanisms that underlie this maternal effect are poorly understood. Carotenoids are hypothesized to enhance antioxidant activity and immune function, and are responsible for the pigmentation of egg yolk. The proximate basis and consequences of this maternal investment, however, have not previously been studied in wild birds. In this supplemental feeding study of lesser black–backed gulls, Larus fuscus, carotenoid–fed females are shown to have increased integument pigmentation, higher plasma concentrations of carotenoids and antioxidant activity, and lower plasma concentrations of immunoglobulins (Igs) in comparison with controls. In turn, carotenoid–fed females produced eggs containing high carotenoid but low Ig concentrations (i.e. passive immunity), whereas control females produced eggs containing low carotenoid but high Ig concentrations. Within–clutch patterns of these resources varied over the laying sequence in a similar manner in both carotenoid–fed and control nests. Our results suggest that carotenoids could be one resource responsible for egg quality maternal effects in birds. We discuss the possible implications of carotenoid–mediated effects on phenotype for fitness in mothers and their offspring.

Effect of selenium and vitamin E content of the maternal diet on the antioxidant system of the yolk and the developing chick

1. The effects of selenium and vitamin E supplementation of the maternal diet on their transfer to the egg yolk and tissues of the newly hatched chick and on the development of the antioxidant system in the chick liver in early postnatal life were investigated. 2. One hundred Cobb broiler breeder hens were divided into 10 equal groups and housed in pens at 25 weeks of age. Each hen received 1 of the treatment diets which included 0.2 or 0.4 mg/kg selenium, 40, 100, 200 mg/kg vitamin E or their combination. After 6 weeks, the hens were artificially inseminated once per week. From week 8, eggs were collected and placed in an incubator. After hatching, chicks from each group were reared (under standard commercial conditions) to 10 d of age. The chicks were fed on a standard starter commercial broiler diet. At the time of hatching, and at 5 and 10 days old, 4 chicks from each group were sacrificed and blood, liver and brain were collected for the subsequent biochemical analyses. 3. The inclusion of organic selenium or vitamin E in the commercial diet significantly increased their concentration in the egg and in the liver of 1-d-old chicks obtained from the eggs enriched with these substances. A positive effect of such dietary supplementation was seen at d 5 and d 10 of postnatal development. 4. There was a positive effect of selenium supplementation of the maternal diet on glutathione concentration in the liver of 1-d-old and 5-d-old chicks. A combination of a dietary selenium supplementation with high vitamin E doses further increased glutathione concentration in the liver. Dietary selenium supplementation significantly increased selenium-dependent glutathione peroxidase (Se-GSH-Px) activity in the liver of the 1-d-old and 5-d-old chicks and decreased liver susceptibility to peroxidation. 6. It is concluded that the nutritional status of the laying hen determines the efficiency of the antioxidant system throughout embryonic and early postnatal development of the offspring.

Neonatal nutrition, adult antioxidant defences and sexual attractiveness in the zebra finch

Early nutrition has recently been shown to have pervasive, downstream effects on adult life–history parameters including lifespan, but the underlying mechanisms remain poorly understood. Damage to biomolecules caused by oxidants, such as free radicals generated during metabolic processes, is widely recognized as a key contributor to somatic degeneration and the rate of ageing. Lipophilic antioxidants (carotenoids, vitamins A and E) are an important component of vertebrate defences against such damage. By using an avian model, we show here that independent of later nutrition, individuals experiencing a short period of low–quality nutrition during the nestling period had a twofold reduction in plasma levels of these antioxidants at adulthood. We found no effects on adult external morphology or sexual attractiveness: in mate–choice trials females did not discriminate between adult males that had received standard– or lower–quality diet as neonates. Our results suggest low–quality neonatal nutrition resulted in a long–term impairment in the capacity to assimilate dietary antioxidants, thereby setting up a need to trade off the requirement for antioxidant activity against the need to maintain morphological development and sexual attractiveness. Such state–dependent trade–offs could underpin the link between early nutrition and senescence.

Designer eggs: from improvement of egg composition to functional food

Abstract Diet plays an important role in maintaining health. Among the different products delivering essential nutrients to the body, an egg has arguably a special place, being a rich and balanced source of essential amino and fatty acids as well some minerals and vitamins. This paper focuses on the benefits to the consumer of improving the nutritional quality of eggs by enhancing levels of anti-oxidants and n-3 fatty acids such as docosahexaenoic acid (DHA). The advantages of simultaneous enrichment of eggs with vitamin E, carotenoids, selenium and DHA include better stability of polyunsaturated fatty acids (PUFA) during egg storage and cooking, high availability of such nutrients as vitamin E and carotenoids, absence of off-taste and an improved anti-oxidant and n-3 status of people consuming these eggs. Having reviewed the relevant scientific literature it is concluded that “designer eggs” can be considered as a new type of functional food.

Tissue-specific differences in antioxidant distribution and susceptibility to lipid peroxidation during development of the chick embryo

The purpose of this study was to determine the tissue-specific acquisition of antioxidant capacity during chick embryo development and to assess the effectiveness of this process in the prevention of lipid peroxidation. The transfer of alpha-tocopherol, carotenoids and ascorbic acid from the yolk/yolk sac membrane (YSM) to the developing chick embryo and the distribution of these antioxidant compounds between the embryonic tissues were investigated. The concentrations of alpha-tocopherol and carotenoids in the yolk decreased between day 15 of development and hatching at day 21, concomitant with an increase in the levels of these antioxidants in the YSM. The concentration of both these lipid-soluble antioxidants in the liver increased dramatically between day 18 of embryonic development and day 1 after hatching. The adipose tissue content of alpha-tocopherol also increased markedly during the late embryonic/early neonatal period. However, the levels of alpha-tocopherol in the liver were far higher than in any other tissue with particularly low levels observed for the brain. Also, carotenoids were undetectable in the developing brain. Ascorbic acid was not present in the initial yolk but high levels of this water-soluble antioxidant were detected in the YSM, particularly at the early stages of development. The concentration of ascorbic acid in the embryonic brain was far higher than in any other tissue. Homogenates of brain tissue were extremely susceptible to lipid peroxidation during incubation in vitro whereas extracts of liver, yolk and YSM were relatively resistant to lipid peroxidation, particularly in the absence of exogenous Fe2+.

Viability, susceptibility to peroxidation and fatty acid composition of boar semen during liquid storage

The changes in viability, susceptibility to peroxidation and fatty acid composition of total phospholipid were studied in boar spermatozoa during 5 day liquid storage in a standard or alpha-tocopherol (alphaT) enriched diluent. The sperm rich fraction of the ejaculates was collected from 6-month old boars. Sperm viability progressively decreased during storage and alphaT inclusion into the diluent significantly inhibited this trend. alphaT inclusion also decreased significantly peroxidation (TBARS production of spermatozoa). Spermatozoa stored in the treatment diluent became rapidly enriched in alphaT with a concomitant decrease of alphaT content in the medium. The proportion of polyunsaturates, mainly 22:6n-3, decreased with a complementary increase in the content of the saturates, mainly 18:0. The inclusion of alphaT into the diluent was effective in totally preventing the significant decrease of 22:6n-3 observed in sperm phospholipid in the control samples during the storage period. It is concluded that the alphaT inclusion in the boar semen diluent increased cell viability through its prevention of an oxidative reduction in the levels of the major polyunsaturated fatty acids, namely 22:6n-3.

Distribution of carotenoids from the yolk to the tissues of the chick embryo

Abstract Laying hens were placed on either a control diet or a carotenoid-supplemented diet. The subsequent concentrations of carotenoids in the yolks of the newly laid fertile eggs (μg carotenoid/g fresh yolk) were 13.3 and 41.1 on the control diet and high-carotenoid diet, respectively. For the day-old chicks derived from the high-carotenoid group, the carotenoid levels in the yolk sac membrane, liver, and plasma were approximately 3 times greater than in the control group; however, the other tissues were less responsive. The proportion of lutein (% wt/wt of total carotenoids) was far lower in the liver of the chick than in the yolk. However, in the non-hepatic tissues the proportion of lutein was generally higher than in the yolk. This suggests that discrimination between different carotenoids may occur in the embryo. For the high-carotenoid group, the peroxidative susceptibility of extracts of the yolk, yolk sac membrane, and liver was decreased compared with samples from the control group. Thus, carotenoids may provide antioxidant protection to the tissues.

Selenium in poultry nutrition 1. Antioxidant properties, deficiency and toxicity

Selenium (Se) has a special place among the feed-derived natural antioxidants, being an integral part of selenoproteins participating in the regulation of various physiological processes in the body. As a part of glutathione peroxidase (GSH-Px) Se belongs to the first and second major levels of antioxidant defence in the cell. There are two major sources of Se for poultry organic selenium, mainly in the form of selenomethionine (SeMet), which can be found in any feed ingredient in varying concentrations and inorganic selenium, mainly selenite or selenate, which are widely used for dietary supplementation. There is a principal difference in metabolism and efficiency of these two forms of selenium, with SeMet being more effective. In fact SeMet possesses antioxidant properties, however, in some conditions selenite can be a pro-oxidant. Se deficiency and excess in modern poultry production are very rare. In general, adequate Se supplementation is considered to be a crucial factor in maintaining the high productive and reproductive characteristics of commercial poultry.

Evaluation in vitro of plant essential oils as natural antioxidants

ABSTRACT Five essential oils, geranium, monarda, nutmeg, oregano and thyme, were evaluated for their antioxidant properties at final concentrations of 0.75 ppm to 100 ppm. Thiobarbituric acid reactive substances (TBARS) were measured in three avian assay systems based on egg yolk, one-day old chicken livers and muscle from mature chickens. All the oils demonstrated extensive antioxidant capacities. The egg yolk TBARS assay showed monarda, nutmeg and thyme essential oils to be the most effective while the chick liver assay revealed nutmeg oil to be the most active. The chicken muscle assay demonstrated equal activity for the oils of monarda, nutmeg, oregano and thyme. Based on this assay technique, oils demonstrating the most effective antioxidant capacities will be chosen for feeding trials to demonstrate their effectiveness in vivo upon polyunsaturated fatty acid (PUFA) metabolism during vital periods of the lifespan, in particular, the foetal/neonate and aging periods.

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.