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The aim of this review is to collate data relevant to understanding the evolution of viviparity in general, and complex placentae in particular. The wide range of reproductive modes exhibited by lizards provides a solid model system for investigating the evolution of viviparity. Within the lizards are oviparous species, viviparous species that have a very simple placenta and little nutrient uptake from the mother during pregnancy (lecithotrophic viviparity), through a range of species that have intermediate placental complexities and placental nutrient provision, to species that lay microlecithal eggs and most nutrients are provided across the placenta during development (obligate placentotrophy). In its commonest form, lecithotrophic viviparity, some uptake of water, inorganic ions and oxygen occurs from the mother to the embryo during pregnancy. In contrast, the evolution of complex placentae is rare, but has evolved at least five times. Where there is still predominantly a reliance on egg yolk, the omphaloplacenta seems to be paramount in the provision of nutrition to the embryo via histotrophy, whereas the chorioallantoic placenta is more likely involved in gas exchange. Reliance on provision of substantial organic nutrient is correlated with the regional specialisation of the chorioallantoic placenta to form a placentome for nutrient uptake, particularly lipids, and the further development of the gas exchange capabilities of the other parts of the chorioallantois.

Carotenoids in the diet of the laying hen are incorporated into the egg yolk and subsequently into the liver and other tissues or 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 front 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.,(c) 2005 Elsevier Inc. All rights reserved.

During avian development, lipoproteins derived from yolk lipid are assembled in the yolk sac membrane (YSM) for secretion into the embryonic circulation. To investigate how yolk polyunsaturated fatty acids, essential for the development of certain tissues, are distributed among the lipid classes of the lipoproteins, pieces of YSM were incubated in vitro with [14C]arachidonic and [14C]docosahexaenoic acids (DHA). There was a marked difference in the partitioning of these two precursors among the lipid classes of the tissue. Of the radioactivity incorporated into total lipid from [14C]-arachidonic acid during 1 h of incubation, 67.3% was esterified as phospholipid and 29.5% as triacylglycerol. In contrast, only 14.6% of the label incorporated from [14C]-DHA was esterified as phospholipid, whereas 73.2% was recovered in triacylglycerol. This pattern of differential partitioning was observed at all time points and across a 20-fold range of fatty acid concentrations. There was no evidence for conversion of the radioactive arachidonic and DHAs to other fatty acids prior to incorporation into tissue lipids. It is suggested that the selective incorporation of yolk-derived DHA into the triacylglycerol of secreted lipoproteins represents part of a mechanism for directing this polyunsaturate to particular embryonic tissues.

Energy metabolism during embryonic development of snakes differs in several respects from the patterns displayed by other reptiles. There are, however, no previous reports describing the main energy source for development, the yolk lipids, in snake eggs. There is also no information on the distribution of yolk fatty acids to the tissues during snake development. In eggs of the water python ( Liasis fuscus), we report that triacylglycerol, phospholipid, cholesteryl ester and free cholesterol, respectively, form 70.3%, 14.1%, 5.7% and 2.1% of the total lipid. The main polyunsaturate of the yolk lipid classes is 18:2n-6. The yolk phospholipid contains 20:4n-6 and 22:6n-3 at 13.0% and 3.6% (w/w), respectively. Approximately 10% and 30% of the initial egg lipids are respectively recovered in the residual yolk and the fat body of the hatchling. A major function of yolk lipid is, therefore, to provision the neonate with large energy reserves. The proportion of 22:6n-3 in brain phospholipid of the hatchling is 11.1% (w/w): this represents only 0.24% of the amount of 22:6n-3 originally present in the egg. This also contrasts with values for free-living avian species where the proportion of DHA in neonatal brain phospholipid is 16-19%. In the liver of the newly hatched python, triacylglycerol, phospholipid and cholesteryl ester, respectively, form 68.2%, 7.7% and 14.3% of total lipid. This contrasts with embryos of birds where cholesteryl ester forms up to 80% of total liver lipid and suggests that the mechanism of lipid transfer in the water python embryo differs in some respects from the avian situation.

The aim of this study was to evaluate effects of modified glucomannans (Mycosorb) on egg yolk and liver of the day-old quail after aurofusarin inclusion in the maternal diet. Fifty-four 45-day-old Japanese quail were divided into three groups and were fed ad libitum a corn-soya diet balanced in all nutrients. The diet of the experimental quail was supplemented with aurofusarin at the level of 26.4 mg/kg feed in the form of Fusarium graminearum culture enriched with aurofusarin or with aurofusarin plus Mycosorb at 1 g/kg feed. Eggs obtained after 8 weeks of feeding were analysed and incubated in standard conditions of 37.5 degrees C/55% RH. Samples of quail liver were collected from day-old hatchlings. Main polyunsaturated fatty acids (PUFAs) of the egg yolk were analysed by gas chromatography, and tocopherols and tocotrienols were analysed by HPLC-based methods. Inclusion of aurofusarin in the maternal diet was associated with decreased proportions of docosahexaenoic acid and increased proportions of linoleic acid in major lipid fractions of the egg yolk as well as with decreased concentrations of alpha- and gamma-tocopherols, alpha- and gamma-tocotrienols in egg yolk and liver of a day-old quail. Inclusion of modified glucomannans (Mycosorb) into the quail diet simultaneously with aurofusarin showed a significant protective effect against changes in PUFA and antioxidant composition in the egg yolk and liver of quail. It is suggested that a combination of mycotoxin adsorbents and natural antioxidants could be the next step in counteracting mycotoxins in animal feed.

Docosahexaenoic acid (DHA) (22:6n−3) is a polyunsaturated fatty acid that is an essential constituent of membranes, particularly of the nervous system. Infants acquire DHA from their mothers, either prenatally via the placenta or postnatally in milk. The present study aimed to test the hypothesis that maternal supplementation during the second and third trimesters of pregnancy enriches maternal and/or fetal DHA status. In a randomised, prospective, double-blind study 100 mothers received either fish-oil capsules containing 400mg DHA/g (200mg/d) (n50), or placebo containing 810mg oleic acid/g (400mg/d) (n50) from 15 weeks gestation until term. Venous blood samples were obtained from mothers at 15, 28 and 40 weeks, and from the umbilical cord at birth. Total fatty acids in plasma and erythrocytes were analysed by GC–MS. There were no significant differences between maternal groups in baseline DHA, as a proportion of total fatty acids (g/100g total fatty acids) or concentration (nmol/ml), in plasma and erythrocytes. DHA concentrations in plasma at 28 weeks (P=0·02) and erythrocytes at both 28 weeks (P=0·03) and term (P=0·02) were 20% higher in supplemented mothers than the placebo group. DHA accounted for a higher proportion of total fatty acids in erythrocytes of supplemented mothers at 28 weeks (P=0·003) and term (P=0·01). There were no significant differences between groups in DHA (g/100g total fatty acids or nmol/l) in cord blood. Maternal DHA status was maximal in mid-trimester and declined to term, at a lower rate in supplemented compared with unsupplemented mothers. Maternal DHA supplementation significantly increases maternal DHA status and limits the last trimester decline in maternal status, aiding preferential transfer of DHA from mother to fetus.

Because the yolk lipids of the king penguin (Aptenodytes patagonicus) contain the highest concentrations of long-chain n-3 polyunsaturated fatty acids yet reported for an avian species, the consequences for the establishment of the brain's fatty acid profile in the embryo were investigated. To place the results in context, the fatty acid compositions of yolk lipid and brain phospholipid of the king penguin were compared with those from three other species of free-living birds. The proportions of docosahexaenoic acid (22:6n-3; DHA) in the total lipid of the initial yolks for the Canada goose (Branta canadensis), mallard (Anas platyrhynchos), moorhen (Gallinula chloropus), and king penguin were (% w/w of fatty acids) 1.0+/-0.1, 1.9+/-0.2, 3.3+/-0.1, and 5.9+/-0.2, respectively. The respective concentrations of DHA (% w/w of phospholipid fatty acids) in brains of the newly hatched chicks of these same species were 18.5+/-0.2, 19.6+/-0.7, 16.9+/-0.4, and 17.6+/-0.1. Thus, the natural interspecies diversity in yolk fatty acid profiles does not necessarily produce major differences in the DHA content of the developing brain. Only about 1% of the amount of DHA initially present in the yolk was recovered in the brain of the penguin at hatch. There was no preferential uptake of DHA from the yolk during development of the king penguin.

The switch from yolk to food (myctophid fishes) as the nutrient source for the newly hatched chick of the king penguin ( Aptenodytes patagonicus) results in a profound change in the pattern of fatty acid provision. This is characterized by major increases in the proportionate intake of n-3 polyunsaturates (20:5n-3 and 22:6n-3) and long chain (C(20-24)) monounsaturates, accompanied by relatively lower levels of n-6 polyunsaturates (18:2n-6 and 20:4n-6). The effects of this change on the fatty acid composition of tissue lipids during the first month of growth, a period of tissue maturation leading to thermal emancipation, were determined. The composition of adipose tissue triacylglycerol responded rapidly to the switch in nutrient source, the proportion of long chain monounsaturates (mainly 20:1n-9 and 22:1n-11) increasing five-fold between hatch and emancipation while the relative levels of 20:5n-3 and 22:6n-3 also increased significantly, by 3- and 1.2-fold, respectively. At emancipation, the fatty acid profile of adipose tissue triacylglycerol was essentially identical to that of the diet. At hatch, the main polyunsaturates of muscle phospholipid were 20:4n-6, 20:5n-3, and 22:6n-3, respectively, forming (w/w of fatty acids) 13.2%, 5.0%, and 12.0%. By emancipation, 20:4n-6 had decreased to 4.8%, 20:5n-3 increased to 10.9%, and 22:6n-3 at 11.4% showed little change. The main polyunsaturate in brain phospholipid at hatch was 22:6n-3 (19.3%): this remained almost constant until day 15 but then increased significantly to 23.6% by emancipation. Significant but minor changes in the proportions of 20:4n-6 (from 5.2% at hatch to 3.5% at emancipation) and 20:5n-3 (from 3.0% to 3.9%) were also observed in brain phospholipid. The data do not allow us to completely distinguish changes that are solely diet driven from those which are a consequence of tissue differentiation. Nevertheless, it is evident that, whereas the fatty acid composition of adipose tissue responds faithfully to the change in nutrient source, the phospholipids of muscle and, especially, of brain are much more refractory to the effects of diet during this period of tissue maturation.

Most reptiles are oviparous, with the developing embryos relying on the contents of the yolk to sustain development until hatching (lecithotrophy). The yolk is composed primarily of lipid and protein, which act as an energy source and the essential components to build embryonic tissue. Nevertheless, yolk and the resulting embryos contain many other nutrients, including inorganic ions, vitamins, carotenoids, water and hormones. Apart from water and oxygen, which may be taken up by eggs, and some inorganic ions that can come from the eggshell or even from outside the egg, everything required by the embryo must be in the egg when it is laid. Approximately 20% of squamate reptiles are viviparous, exhibiting a variety of placental complexities. Species with complex placentae have reduced yolk volumes, with the mother augmenting embryonic nutrition by provision across the placenta (placentotrophy). Despite assumed advantages of placentotrophy, only 5 out of approximately 100 lineages of viviparous squamates exhibit substantial placentotrophy. This paper reviews available and recent information on the yolk contents of a variety of squamate reptiles to ask the question, how are nutrients transported from the yolk to the embryo or across the placenta? Although, current available data suggest that, in broad terms, yolk is taken up by embryos without discrimination of the nutrients, there are some apparent exceptions, including the very long chain polyunsaturated fatty acids. In addition, fundamental differences in the patterns of energy utilisation in lizards and snakes suggest fundamental differences in lipid profiles in these taxa, which appear to reflect the differences between placentotrophic and lecithotrophic viviparous lizards.

The fatty acid compositions of yolk lipids of eggs collected in the wild from five species of ducks (Anatidae) showing a range of dietary preferences, the king eider Somateria spectabilis, the lesser scaup Aythya affinis, the mallard Anas platyrhynchos, the green-winged teal Anas crecca and the gadwall Anas streperi, are reported. For all five species, the fatty acid profiles conformed to a similar pattern, characterized by relatively balanced proportions (w/w) of arachidonic (6.7‐9.1%) and docosahexaenoic (5.9‐7.0%) acids in yolk phospholipid. This contrasts markedly with the yolk phospholipid of current commercially-reared ducks where the proportion of arachidonic acid can be 10 times greater than that of docosahexaenoic acid. It was most notable that the similarities in yolk fatty acid profiles among the different species of wild ducks were achieved despite the considerable interspecies variation in dietary modes. It seems that, in this instance, genetic factors deriving from a common phylogeny may be more important than dietary differences in determining the fatty acid composition of yolk.

Since the yolk lipids of the king penguin (Aptenodytes patagonicus) naturally contain the highest concentrations of DHA and EPA yet reported for the eggs of any avian species, the effects of this (n-3)-rich yolk on the FA profiles of the embryonic heart and skeletal muscle were investigated. The concentrations (mg/g wet tissue) of phospholipid (PL) in the developing heart and leg muscle of the penguin doubled between days 27 and 55 from the beginning of egg incubation (i.e., from the halfway stage of embryonic development to 2 d posthatch), whereas no net increase occurred in pectoral muscle. During this period, the concentration of TAG in heart decreased by half but increased two- and sixfold in leg and pectoral muscle, respectively. The most notable change in cholesteryl ester concentration occurred in pectoral muscle, increasing ninefold between days 27 and 55. Arachidonic acid (ARA) was the major polyunsaturate in PL of the penguin's heart, where it formed about 20% (w/w) of FA at day 55. At the equivalent developmental stage, the heart PL of the chicken contained a 1.3-fold greater proportion of ARA, contained a fifth less DHA, and was almost devoid of EPA, whereas the latter FA was a significant component (7% of FA) of penguin heart PL. Similarly, in PL of leg and pectoral muscle, the chicken displayed about 1.4-fold more ARA, up to 50% less DHA, and far less EPA in comparison with the penguin. Thus, although ARA-rich PL profiles are achieved in the heart and muscle of the penguin embryo, these profiles are significantly affected by the high n-3 content of the yolk.

The effects of aurofusarin in the quail diet on the antioxidant systems of the developing embryo are investigated. Thirty eight 45-day-old Japanese quails (Coturnix japonica) were divided into two groups and were fed on a corn-soya diet or the same diet supplemented with aurofusarin at the level of 26.4 mg/kg feed in the form of Fusarium graminearum culture enriched with aurofusarin. Eggs obtained after 7 weeks of feeding were incubated. Samples of quail tissues were collected at day 17 of embryonic development and from day old hatchlings. Antioxidants and malondialdehyde were analysed by HPLC-based methods. Inclusion of aurofusarin in the maternal diet was associated with decreased concentrations of alpha- and gamma-tocopherols, alpha- and gamma-tocotrienols, retinol, lutein and zeaxanthin in egg yolk. The vitamin E (tocopherols and tocotrienols) concentration in the liver and yolk sac membrane (YSM) of the day 17 embryos and the hatchlings from aurofusarin-fed group was significantly decreased. Alpha-tocopherol concentration was also reduced in kidney, lung, heart, muscle and brain of day-old quails. In the liver of day-old quails, concentrations of lutein, zeaxanthin, retinol, retinyl linoleate, retinyl oleate, retinyl palmitate and retinyl stearate were also reduced. As a result of these diminished antioxidant concentrations, tissue susceptibility to lipid peroxidation was significantly increased. It is suggested that a compromised antioxidant system of the egg yolk and embryonic tissues could predispose quails to increased mortality at late stages of their embryonic development.

1. The effect of the mycotoxin aurofusarin on the antioxidant composition and fatty acid profile of quail eggs was investigated. 2. Thirty eight 45-d-old Japanese quails were divided into two groups (experimental and control, 15 females +4 males in each group) and were fed on a maize-soya diet balanced in all nutrients. The diet of the experimental quails was supplemented with aurofusarin at the level of 26.4 mg/kg feed in the form of Fusarium graminearum culture enriched with aurofusarin. At the beginning and after 2, 4 and 8 week supplementation periods, eggs were collected and analysed. After 8 weeks of supplementation, experimental quails were fed on unsupplemented diet during the next 4 weeks and eggs were collected after 2 and 4 weeks on such a diet and analysed. 3. Aurofusarin caused a significant (P

Eight mid-lactation Holstein-Friesian dairy cows were used in an experiment to investigate whether poor transfer to milk of (n-3) long chain (≥C20) poly-unsaturated fatty acids (n-3 LCPUFA), from diets containing fish oil, is related to their mode of transport in plasma lipoproteins. The cows were split into two groups of four, each of which was housed with 24 other cows which did not provide blood data in this experiment. All cows received a basal diet ad libitum consisting of (kg/t dry matter) silage (539), grain distillers’ grains (148), rolled barley (248) and soya (65). All cows also received a mid-day meal of 2·76 kg per cow per day of molassed sugar-beet shreds. The control group (C) received no oil supplement but those in the treatment group (F) received 300 g per cow per day of fish oil absorbed onto the sugar-beet shreds. Fish oil inclusion progressively depressed milk fat concentration of the four cows from each group over the 3 weeks of the experiment so that levels were approximately 20 g/kg lower for cows in treatment F than for those in C (P < 0·05). Mean concentrations over all cows of the long-chain (≥C20, n-3) poly-unsaturated fatty acids in milk fat (g/100 g) were 0·12 and 0·54 for treatments C and F respectively, whilst corresponding output in milk (g/day) increased from 116 to 3·91, an average efficiency of transfer of 4·6%. The fatty acid compositions of the lipoproteins were measured in plasma samples from the four cows from each group after 3 weeks on the experimental diets The proportions (g/100 g fatty acids) of C20: 5 (n-3) in cholesteryl (CE) and phospholipid (PL) of high-density lipoprotein (HDL) in the plasma were respectively increased from 0·97 to 4·39 (P < 0·05) and from 1·15 to 4·74 (P < 0·01) by the fish-oil supplementation. For C22: 6 (n-3), the proportions in CE and PL of HDL respectively increased (P < 0·001) from 0·02 to 0·23 and from 0·16 to 2·18 as a result of the supplementation. The mean proportions (g/100 g fatty acids) of C20: 5 (n-3) and C22: 6 (n-3) in the triglyceride fraction of very low-density lipoprotein were 1·05 and 2·3 respectively and were not significantly altered by fish-oil supplementation (P > 0·05). It is suggested that the low transfer efficiency of (n-3) LCPUFA to the milk is partly due to their transport in the plasma largely as components of HDL lipids which are unavailable to the mammary gland.

Piscivorous birds consume diets which are rich in highly-polyunsaturated n-3 fatty acids; these play vital roles in embryonic development but are very susceptible to oxidative damage. The effects of such diets on the fatty acid composition and antioxidant content of the yolk were investigated in the northern gannet Morus bassanus, the great skua Catharacta skua, the American white pelican Pelecanus erythrorhynchos and the double-crested cormorant Phalacrocorax auritus. The phospholipid fraction of the eggs of these four species contained high proportions of the n-3 fatty acid, docosahexaenoic acid, which formed 7.5‐11.3% (w/w) of the fatty acids of this fraction. The presence of eicosapentaenoic and docosapentaenoic acids also contributed to the total n-3 content of the phospholipid. The n-6 polyunsaturate, arachidonic acid, formed between 8% and 19% (w/w) of the phospholipid fatty acids. For the pelican and cormorant, this is consistent with the consumption of freshwater fishes in which arachidonic acid may be a significant acyl constituent. This finding is, however, more difficult to explain for the gannet and skua which largely consume marine fish with a low arachidonic acid content. The yolks of all four species contained relatively high concentrations of vitamin E (90.2‐302.3 m gg 71 wet yolk) which was mainly present as a-tocopherol. The eggs of the pelican and cormorant were especially enriched in carotenoids (150.9 and 115.7 m gg 71 wet yolk, respectively).

The concentrations (microg/g wet yolk) of total carotenoids in eggs of the common moorhen (Gallinula chloropus), American coot (Fulica americana) and lesser black-backed gull (Larus fuscus), collected in the wild, were 47.5, 131.0 and 71.6, respectively. In contrast to data for eggs of the domestic chicken, beta-carotene was a significant component in the yolks of these three wild species, forming 25-29% by wt. of the total carotenoids present. The concentration of total carotenoids in the livers of the newly-hatched chicks was 5-10 times higher than in the other tissues and beta-carotene was again a major component, forming 37-58% of the hepatic carotenoids. In the newly-hatched gull, the proportions of both lutein and zeaxanthin were very low in the liver but high in the heart and muscle when compared with the yolk. By contrast canthaxanthin, echinenone and beta-carotene were very minor constituents of heart and muscle when compared with their proportions in the yolk of the gull. The proportions of lutein and zeaxanthin in the liver of the newly-hatched coot and moorhen were also far lower than in the yolk whereas the liver was relatively enriched with beta-cryptoxanthin, beta-carotene and (in the moorhen) echinenone. The results indicate that avian embryos discriminate between different carotenoids during their distribution from the yolk to the various tissues.

This study examines the transfer of lipids from the yolk to the embryo of the king penguin, a seabird with a high dietary intake of n–3 fatty acids. The concentrations of total lipid, triacylglycerol (TAG), and phospholipid (PL) in the yolk decreased by ∼80% between days 33 and 55 of development, indicating intensive lipid transfer, whereas the concentration of cholesteryl ester (CE) increased threefold, possibly due to recycling. Total lipid concentration in plasma and liver of the embryo increased by twofold from day 40 to hatching due to the accumulation of CE. Yolk lipids contained high amounts of C20–22n–3 fatty acids with 22:6(n–3) forming 4 and 10% of the fatty acid mass in TAG and PL, respectively. Both TAG and PL of plasma and liver contained high proportions of 22:6(n–3) (∼15% in plasma and >20% in liver at day 33); liver PL also contained a high proportion of 20:4(n–6) (14%). Thus both 22:6(n–3) and 20:4(n–6), which are, respectively, abundant and deficient in the yolk, undergo biomagnification during transfer to the embryo.

Niveoscincus ocellatus is an important species in historical analyses of the evolution of viviparity because it is the species upon which the type II chorioallantoic placenta was based. Here we describe the net nutrient uptake across the placenta of N. ocellatus for comparison with other species of skinks with complex placentae. N. ocellatus is highly placentotrophic, with neonates being 1.68-times larger in dry matter than the fresh eggs. There is an increase of nitrogen from 6.3 +/- 0.2 mg to 9.2 +/- 0.6 mg, and ash from 3.8 +/- 0.3 mg to 6.7 +/- 0.6 mg. The increase in ash is made up by a more than two-fold increase in the amounts of calcium, potassium and sodium. There is no significant difference in lipids in the neonates compared to fresh eggs, so considerable lipid must have crossed the placenta to provide energy for embryonic development. N. ocellatus is significantly more placentotrophic than Niveoscincus metallicus, which also has a complex chorioallantoic placenta. Discovery of substantial placentotrophy in this genus confirms that two lineages of Australian lygosomine skinks (represented by the genera Pseudemoia and Niveoscincus) have evolved this pattern of embryonic nutrition and supports the hypothesis that the evolution of reptilian placentotrophy involves specialisations in addition to structural modifications of the chorioallantoic placenta.

We have reviewed published and new quantitative data on the net uptake of nutrients by embryos of oviparous and viviparous lizards that vary in chorioallantoic placental complexity to better understand the evolution of complex placentae. We assessed net nutrient uptake during embryonic development by measuring the total dry mass, or the mass of separate nutrients, in the egg at about the time of ovulation and in the neonate. There is no significant difference in the fresh egg to neonate dry mass ratio of oviparous and viviparous species that have simple placentae, indicating that there is little, if any, net uptake of nutrients by viviparous species with simple chorioallantoic placentae. In contrast, there is significant uptake of dry matter and individual nutrients across the placenta of species with complex chorioallantoic placentae. Species of the genus Niveoscincus have a range of placentae and nutrient uptakes, even among populations of one species, suggesting that further studies among populations of single species are required. Data are available for relatively few clades, and all the data for the three most complex chorioallantoic placental types are derived from a single genus. Thus, further research on new genera of lizards is required to overcome the potentially confounding effects of phylogeny in our analyses.

Objective: To evaluate the ability of designer eggs enriched in vitamin E, lutein, selenium (Se) and docosahexaenoic acid (DHA) to deliver micronutrients to the human in a palatable and visually acceptable form. Design: Double-blind, placebo-controlled trial, two treatment groups balanced for sex and age. Setting: Department of Biochemistry and Nutrition, SAC, Scotland. Subjects: Forty healthy adult volunteers completed the study. Volunteers were recruited among staff of the Scottish Agricultural College Interventions: Volunteers consumed, for 8 weeks, either a designer egg or a normal table egg per day. Fasting blood samples were taken before and at the end of the study. Results: Consumption of designer eggs enriched in vitamin E, lutein, Se and DHA significantly increased the levels of α-tocopherol, lutein and DHA in plasma as compared to the changes found after consumption of normal table eggs, with the largest increases found in plasma lutein (1.88-fold increase). The proportion of DHA was increased in all the main lipid classes of the plasma including triacylglycerol (2.3-fold), free fatty acids (1.6-fold), cholesteryl ester (1.4-fold) and phospholipid (1.3-fold). Egg consumption did not change Se concentration in plasma, blood pressure, total plasma lipid concentrations or the concentrations of total cholesterol and HDL-cholesterol in plasma. Conclusion: Consumption of designer eggs enriched in vitamin E, lutein, DHA and Se as part of normal diet for 8 weeks effectively increased the blood levels of α-tocopherol, lutein and DHA. Sponsorship: Scottish Office Agriculture, Environment, and Fisheries Department. European Journal of Clinical Nutrition (2000) 54, 298–305

Recent studies on chicken semen have suggested that the lipid and fatty acid composition of spermatozoa may be important determinants of fertility. Phospholipid fatty acid composition, vitamin E content and in vitro susceptibility to lipid peroxidation of duck spermatozoa were investigated using GC-MS and HPLC based methods. The total phospholipid fraction of duck spermatozoa was characterized by high proportions of the n-6 polyunsaturated fatty acids arachidonic (20:4n-6), docosatetraenoic (22:4n-6) and docosapentaenoic (22:5n-6) acids but a substantial proportion of the n-3 fatty acid docosahexaenoic (22:6n-3) acid was also present. Palmitic (16:0) and stearic (18:0) fatty acids were the major saturates in sperm phospholipids. Among the phospholipid classes, phosphatidylserine (PS) had the highest degree of unsaturation due to very high proportions of 22:6n-3, 22:5n-6, 22:4n-6 and 20:4n-6, comprising together more than 75% of total fatty acids in this fraction. Phosphatidylethanolamine (PE) also contained high proportions of these four C 20–22 polyunsaturates, which together formed 60% of total fatty acids in this phospholipid. Spermatozoa and seminal plasma of duck semen were characterized by unexpectedly low content of vitamin E, being more than 4-fold lower than in chicken semen. In duck semen the major proportion of the vitamin E (>70%) was located in the spermatozoa. The very high proportion of 22:6n-3 in PS and PE fractions of duck sperm lipids and the comparatively low levels of vitamin E could predispose semen to lipid peroxidation. Nevertheless the in vitro susceptibilities to Fe 2+ -stimulated lipid peroxidation of duck and chicken spermatozoa were very similar. The results of the study suggest that increased superoxide dismutase and glutathione peroxidase activity and increased antioxidant activity of seminal plasma may compensate for the low levels of vitamin E to help protect the membranes of duck spermatozoa, which exhibit a high degree of unsaturation from oxidative stress.

The effects of three fat supplements on milk yield and composition were measured using 12 mid-lactation in-calf Hoistein-Friesian cows in a balanced incomplete change-over design over three periods each of 3 weeks. All cows received a basal diet consisting of 36 kg/day grass silage (dry matter (DM) 270 g/kg, metabolizable energy (ME) 11·6 MJ/kg DM) and 7 kg/day o f a concentrate mixture containing (g/kg) rolled barley (501), molassed sugar-beet pulp shreds (277), soya-bean meal (208) and a standard cow mineral supplement (14). Treatments were CON (control-no supplement); LIN and FISH (250 gl day of either linseed oil or marine oil, providing approximately 0·046 of ME intake) or TOA (95 glday of tuna orbital oil, providing 0·018 of total ME intake).There were no significant effects on silage DM intake or milk yield (means 9·25 and 17·2 kg/day respectively). The FISH and TOA treatments depressed (F < 0·05) milk fat concentration (45·4, 44·6, 34·5 and 41·6 (s.e.d. 1·08) g/kg for CON, LIN, FISH and TOA respectively; note — the same treatment order is used for all results quoted). Compared with values for CON, yield of f at (glday) was significantly (F < 0·05) greater for LIN and significantly lower for FISH (739, 808, 572 and 732, s.e.d. 28·7). All three oil supplements reduced (F < 0·05) milk protein content (33·6, 32·5, 30·6 and 32·4 (s.e.d. 0·43) g/kg) but, apart from a small increase for LIN, protein yield (glday) was unaffected (545, 586, 510 and 574, s.e.d. 20·2).The concentrations (g/100 g) of short-chain fatty acids (< C14) and C16 : 0 in milk f at were lower (F < 0·05) for LIN than for the other treatments. All supplements increased the concentrations ofC18:1 (F < 0·05), the value for LIN being greater (F < 0·05) than for the other treatments (21·0, 27·2, 25·3 and 23·7, s.e.d. 0·74). The FISH and TOA treatments increased (F < 0·05) the concentrations of long chain (< C2O) (n-3) poly-unsaturated fatty acids (PUFA), (0·19, 0·17, 0·49 and 0·27, s.e.d. 0·026) but less than proportionately 0·03 of dietary intake of these acids was transferred to milk, probably because they were found to be mostly in the phospholipid and cholesterol ester fractions of plasma. The FISH and TOA treatments increased (F < 0·05) the percentages of total trans fatty acids in milk fat (1·13, 2·19, 10·26 and 3·62, s.e.d. 0·728) whilst a significant (F < 0·05) increase in conjugated linoleic acid (CLA) was observed only for FISH (0·16, 0·28, 1·55, and 0·52, s.e.d. 0·154). Concentrations of CLA and total trans acids in milk were highly correlated (r = 0·91, no. =36, F < 0·001) whilst trans acids in milk were inversely correlated with milk fat content (r = -0·63, no. = 36, F < 0·001) supporting the theory that milk fat depression may be caused by increased supply of trans fatty acids to the mammary gland. The health implications of these changes in milk fat composition are discussed.

Lipid analysis was performed on freshly ovulated eggs (n = 5) of the oviparous lizard Bassiana duperreyi. The fresh weight of the whole egg contents was 132.0 +/- 4.3 mg (mean +/- SE) of which lipid constituted 21.9 +/- 1.1% (w/w). Triacylglycerol formed an exceptionally high proportion (85.4 +/-0.5%, w/w) of the total lipid, whereas phospholipid, free cholesterol, cholesteryl ester, and free fatty acid, respectively, contributed 11.2 +/- 0.3, 1.4 +/- 0.1, 1.3 +/- 0.1, and 0.6 +/- 0.1% of the total lipid mass. Linoleic and alpha-linolenic acids were the major polyunsaturates of the triacylglycerol fraction, respectively, forming 16.3 +/- 0.1 and 8.3 +/- 0.1% (w/w) of the fatty acids. Linoleic acid was the major fatty acid (29.0 +/- 0.1%) of the total phospholipid, which also contained substantial amounts of arachidonic (6.4 +/- 0.1%) and eicosapentaenoic (3.0 +/- 0.1%) acids, but a relatively low proportion (1.6 +/- 0.1%) of docosahexaenoic acid. Phosphatidylcholine formed the major phospholipid class (73.8 +/- 2.3%) w/w of total phospholipid) and was enriched in linoleic acid, whereas phosphatidylethanolamine, which formed 20.4 +/- 1.9%(w/w) of total phospholipid, contained higher proportions of arachidonic and docosahexaenoic acids.

The ion, energy, lipid, nitrogen and fat-soluble vitamin contents of freshly ovulated eggs and neonates of the viviparous lizard Niveoscincus metallicus were measured to quantify uptake of nutrients across the placenta. This species is particularly interesting because it has a chorio-allantoic placenta that is intermediate in complexity compared to viviparous species that have been the focus of other studies. Newly ovulated eggs have a wet mass of 79.6+/-4.6 mg and a dry mass of 41.8+/-2.8 mg, compared to the neonates that have a wet mass of 224.2+/-8.2 mg and dry mass of 37.9+/-1.2 mg. Thus, there is no significant net uptake of dry matter across the placenta. Neonates have significantly less lipid (6.2+/-0.4 mg) than eggs (12.7+/-0.5 mg), but no significant difference in nitrogen (4.1+/-0.3 mg) compared to eggs (4.5+/-0.2 mg). Energy densities reflect the protein and lipid composition and the relative dry masses of the eggs and neonates. There is significantly more energy (1029.1+/-80.0 J) in the egg than in the neonate (858.2+/-38.6 J). The increase in the ash content of the neonates (2.9+/-0.2 mg) compared to fresh eggs (2.1+/-0.3 mg) was not significant, even though there was an approximately threefold increase in the amount of sodium (0.11+/-0.01 mg in neonates, 0.34+/-0.01 mg in eggs) and potassium (0.12+/-0.017 in neonates, 0.40+/-0.01 mg in eggs) in neonates compared to eggs. There was no significant uptake of calcium and magnesium during development. The egg lipids consisted of triacylglycerol (66.7+/-2.3 %), phospholipid (18.9+/-0.7 %), cholesteryl ester (4.9+/-1.6 %) and free cholesterol (5.6+/-1.5 %). The egg phospholipid contained comparatively high proportions of arachidonic and eicosapentanoic acids but low levels of docosahexaenoic acid (DHA), whereas the phospholipid of the neonate was greatly enriched in DHA. In the egg, the predominant vitamin E was (agr;)-tocopherol (62.6+/-3.4 mg g(-)(1)), although there was some (ggr;)-tocotrienol (3.5+/-0.3 mg g(-)(1)), and vitamin A was present (1.5+/-0.2 mg g(-)(1)). The ratio of neonate dry mass to egg dry mass of N. metallicus (0.91) lies between that of species with type I (0.78) and type III (1.70) chorio-allantoic placentae, confirming our conclusion that the placenta of N. metallicus is functionally intermediate, as well as intermediate in complexity, between these other two types.

The aim of this study was to assess the differences in yolk lipid composition of pheasants and geese between birds maintained in captivity on commercial grain-based diets and their counterparts in the wild which are free to select their diets from the environment. The most striking difference was that the proportion of α-linolenic acid (18:3n-3) was far greater in all yolk lipid classes [triacylglycerol (TAG), phospholipid (PL), cholesteryl ester (CE)] of the wild birds than in the captive birds of both species. For example, in yolk TAG, the level (wt.% of total fatty acids) of 18:3n-3 was only 1.6% in eggs of captive pheasants compared with 27.9% in eggs of the wild birds. The proportions of 18:3n-3 in yolk TAG of housed, free-range and feral geese were 0.6, 6.6 and 19.3% respectively. It is suggested that these differences arise from the predominance of linoleic acid (18:2n-6) as the major polyunsaturate in the commercial grain-based feeds whereas geese and pheasants in the wild consume grasses and green shoots in which 18:3n-3 is the main fatty acid. The concentrations of vitamin E and carotenoids in the yolks of the free-range and feral geese were much greater than in those of the housed geese. Thus the developing embryos of pheasants and geese in the wild will have access to far higher levels of n-3 polyunsaturates and lipid-soluble antioxidants compared with embryos of the housed birds.

Energy, ionic, protein and lipid contents and fatty acid profiles for the major lipid classes of freshly ovulated eggs and neonates of the viviparous lizard, Pseudemoia spenceri, were measured. Litter size is 1.7 ± 0.1, with larger females producing larger neonates. Placentotrophy results in approximately 23% more dry matter in the neonates than in the fresh egg. The increase in the quantity of protein and lipid during development is not significant and is reflected in the similarity of energy densities of eggs and neonates. As a percentage of dry matter, neonates have slightly lower proportions of lipid and protein than eggs because of significant uptake of ash, calcium, potassium and sodium, but not of magnesium, across the placenta. The amounts of triacylglycerol and phospholipid are not significantly different between the egg and the neonate, but neonates contain significantly more cholesterol and cholesteryl ester. The amounts of the major fatty acids, palmitic and oleic acids, recovered from the total lipids of the neonate do not differ significantly from the amounts present in the egg lipids, but the neonates contain significantly less linoleic and α-linolenic acids and more palmitoleic, stearic and arachidonic acids than the eggs. The amount of docosahexaenoic acid recovered from the lipids of the neonate is 2.6-times greater than the amount initially present in the egg. P. spenceri has a relatively larger egg and a smaller reliance on placentotrophy than other species in the same genus, all of which have a similar placental morphology. Nevertheless, the pattern of embryonic nutrition includes both obligative and facultative placentotrophy. All the major components of yolk of oviparous species are present in eggs of P. spenceri, but most are augmented during development by placental transfer.

The composition of egg yolks and neonates of the viviparous lizard, Pseudemoia pagenstecheri, one of the most placentotrophic reptiles studied to date, are described. Neonates (43.3 ± 5.2 mg) have twice the dry mass of the initial eggs (22.0 ± 1.9 mg). The protein content of neonates (29.1 ± 1.1 mg) is more than twice that of eggs (12.2 ± 1.1 mg), while the energy content (908.1 ± 107.4 J) is 1.6 times higher than that of the egg (565.0 ± 42.9 J). The energy densities of eggs (27.5 kJ g−1) and neonates (23.1 ± 0.3 kJ g−1) are similar to the energy densities of eggs and neonates of oviparous species. The total ash per neonate (4.1 ± 0.4 mg) is three times greater than that of the egg contents (1.4 ± 0.2). Neonates contain significantly more calcium, sodium and potassium, but not magnesium, than do eggs. Thus, the placenta has a quantitatively important role in supplying nutrients for the embryo. The proportions of triacylglycerol (66%), phospholipid (19%), and free cholesterol (5%) in the eggs are similar to those in eggs of birds and crocodilians, but the proportion of cholesteryl esters (7%) is much higher in eggs of P. pagenstecheri. The proportion of docosahexaenoic acid in the egg phospholipid is relatively low (1.4%) but rises to 5.4% in the neonate. The eggs contain vitamin E (mainly in the form of α-tocopherol) and vitamin A, but no detectable carotenoids. The overall composition of the eggs is not substantially different from that of oviparous species, suggesting that the small egg size relative to neonate size is a result of a reduction in egg size rather than modification by omission of some nutrients from the yolk. The pattern of placental nutrient provision of P. pagenstecheri contains both an obligate and a facultative component suggesting that enhancement of offspring quality through facultative placentotrophy is a general characteristic of placental reptiles independent of pattern of embryonic nutrient provision.

1. Within-clutch variation in parental investment of yolk lipid (including essential fatty acid composition and fat-soluble vitamin content) was investigated in whole clutches of three eggs of Lesser Black-backed Gulls, Larus fuscus. 2. Although there were no significant differences between years in egg size or yolk mass among eggs of the same laying order, eggs collected in 1996 had significantly lower lipid content than those collected in 1997. 3. In both years third-laid c-eggs were smaller, had a smaller mass of yolk and had significantly lower yolk lipid mass compared with earlier laid (a- and b-) eggs. 4. Despite this lower lipid mass of c-eggs, of the different lipid fractions only cholesterol content of c-eggs was significantly lower than that of a- or b-eggs. 5. Earlier laid eggs had greater amounts of arachidonic acid in the phospholipid and cholesterol ester fractions of yolk lipid, and considerably greater quantities of vitamin E and carotenoids. 6. Conversely, levels of linoleic acid and vitamin A were equalized among eggs of different laying sequence as both these essential nutrients have primarily systemic roles. 7. The probable effect of increased antioxidant (vitamin E and carotenoid) content of earlier-laid eggs is to enhance embryonic and neonatal growth and development, reduce susceptibility to pathogens and increase the ability of the embryo to withstand the oxidative stress associated with hatching. 8. The results suggest that there is maternal bias of essential nutrients to offspring with the highest reproductive value in order to maximize reproductive success.

Differences between four avian species of commercial importance (chicken, turkey, duck and goose), in terms of the relationship between the dietary fatty acids supplied in the diet of the layers and the fatty acid composition of the egg yolk lipids, were investigated. Laying hens of the four species were provided with diets with very similar fatty acid compositions. The polyunsaturated fatty acid content of the diets consisted of linoleic and α-linolenic acids at approximately 50% and 6% (w/w of total fatty acids), respectively, for all four species. In spite of the very similar dietary provision of fatty acids, the subsequent fatty acid profiles of the yolk lipids differed markedly between the four species. In particular, the proportion of docosahexaenoic acid in the total lipid of the yolk was three to five times greater for the chicken compared to the other three species. By contrast, the proportion of arachidonic acid in total yolk lipid was approximately two times greater for the goose and duck than for the chicken and turkey. Thus the chicken was more efficient at incorporating long-chain (C22 ) fatty acid of the n-3 series into yolk lipid whereas the duck and goose preferentially incorporated C20 fatty acid of the n-6 series. The turkey eggs contained a similar proportion of arachidonic acid but less docosahexaenoic acid than the chicken eggs. The main differences between the avian species in terms of the yolk levels of C20 –22 polyunsaturated fatty acids were in the phospholipid fraction since only low levels of these fatty acids were present in the triacylglycerol fraction. The relative proportions of docosahexaenoic acid in the phospholipid and triacylglycerol fractions of the livers of the newly-hatched chicks of the four species reflected the differences displayed by the yolks. The proportions of arachidonic acid in these liver lipid fractions, however, did not reflect the species differences in yolk lipid composition. © 1999 Society of Chemical Industry

The activity of acyl-coA:cholesterol acyltransferase, the enzyme responsible for the conversion of free cholesterol to cholesteryl ester, was measured in the microsomal fraction of the yolk sac membrane of the alligator ( Alligator mississippiensis ) embryo at various stages of development. For embryos developing at 33°C, the activity of the enzyme (pmol cholesteryl ester synthesised min −1 mg microsomal protein −1 ) increased from 368.3±78.3 at day 30 to 1584.8±46.2 at day 50 of development when using the cholesterol endogenous to the microsomes as substrate. The addition of an optimal concentration of exogenous cholesterol to the assay mixture stimulated the activity by nearly two-fold at day 40 but produced no significant stimulation at days 50 and 60. Cholesteryl ester hydrolase activity was very low in the microsomes and undetectable in the cytosol at all stages. Also, the cytosol contained a factor which inhibited cholesteryl ester hydrolase. Thus the enzymic capacity of the yolk sac membrane is strongly directed towards the net esterification of incoming yolk-derived cholesterol.

The aim of this study was to determine the major nutritive components present in fresh eggs of the freshwater turtle, Emydura macquarii , and to investigate the utilisation of these components during embryonic development. Comparison of the compositions of the initial egg contents (yolk plus albumen), the hatchling and the residual yolk indicated that embryonic development was accompanied by the loss of approximately 15% of the initial dry matter, 25% of the energy content, 8.8% of the protein and 41% of the lipid. Thus, in addition to oxidation of fatty acids, some of the energy consumed during development (17.6%) was derived from catabolism of protein. A feature of the yolk lipids was the presence of high proportions of α -linolenic acid (18:3n-3), particularly in the triacylglycerol and a high concentration of α -tocopherol, similar to than in the yolk of birds. The yolk phospholipid contained a high concentration of arachidonic acid (20:4n-6) and eicosapentaenoic acid (20:5n-3) but a relatively low amount of docosahexaenoic acid (DHA) (22:6n-3). By contrast, the phospholipid of the hatchling was enriched in DHA but contained only a small concentration of eicosapentaenoic acid, suggesting the possible conversion of eicosapentaenoic acid to DHA by the embryo. The amount of calcium recovered in the hatchling was almost twice that of the initial egg contents suggesting mobilisation of calcium from the shell.

The lipids of the yolk represent the primary nutrient source for the chick embryo, providing over 90% of the energy required for development as well as supplying a range of structural components for membrane biogenesis. Since the energy needs and the requirements for particular fatty acids differ greatly among the various embryonic tissues and between successive developmental stages, the regulated distribution of lipid components from the yolk to the different body sites forms a central feature of this system. As a consequence, the various tissues of the newly hatched chick display a range of highly characteristic lipid and fatty acid compositions in accordance with their functions but which, in many cases, also reflect the intensity and complexity of the lipid transfer process in the embryo. For example, the liver of the chick contains very high levels of cholesteryl ester as a result of the mechanism of lipid transfer. Moreover, the triacylglycerol fraction of the liver is highly enriched in docosahexaenoic acid, possibly reflecting hepatic involvement in the transfer of this fatty acid to the brain. The accretion of large amounts of both docosahexaenoic and arachidonic acids in the phospholipids of the brain and retina is a key feature of chick embryo development, the importance of which is underlined by the expression of a series of mechanisms, possibly mediated by the liver and adipose tissue, designed to promote the transfer of these fatty acids to the neural tissues.

The aim of this study was to investigate the possibility of biodiscrimination between different forms of vitamin E during the development of the chick embryo. The vitamin E present in the initial yolk consisted of alpha-tocopherol (90%), (beta + gamma)-tocopherol (8%), alpha-tocotrienol (0.3%) and (beta + gamma)-tocotrienol (1.3%). In marked contrast, the vitamin E recovered from the bile of the day-16 embryo contained much higher proportions of alpha-tocotrienol (10%) and especially of (beta + gamma)-tocotrienol (42%). By the time of hatching, 56% of the vitamin E present in the bile was in the form of (beta + gamma)-tocotrienol. The residual yolk of the newly-hatched chick contained far greater proportions of alpha-tocotrienol (2.6%) and (beta + gamma)-tocotrienol (10%) than were present in the initial yolk. The results suggest that the liver of the embryo may selectively excrete tocotrienols as components of bile, whilst retaining the tocopherols within the hepatocytes. The increased proportions of tocotrienols in the residual yolk may result from the recycling of bile from the gall bladder to the yolk. The liver of the day-old chick contained alpha-tocopherol as the main form of vitamin E (90%) with only a small proportion (0.2%) of (beta + gamma)-tocotrienol. The alpha-tocopherol form was also the main vitamin E component in the brain (85%), heart (79%), lung (82%) and adipose tissue (91%) of the day-old chick. The present study suggests the occurrence of a high degree of biodiscrimination between tocopherols and tocotrienols during the development of the chick embryo.

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.

The relationship between the levels of the lipid-soluble antioxidants, a-tocopherol and carotenoids, in the parental diet, the yolk and the neonatal tissues was investigated for four avian species of commercial importance. The chicken displayed a much greater efficiency in incorporating a-tocopherol from the parental diet into the yolk in comparison with the turkey, duck and goose. Thus, in spite of similar concentrations in the respective diets, the resultant con- centration of a-tocopherol in the yolk of the chicken egg was four to -ve times greater than observed for the other three species. A similar but less dramatic picture was observed for carotenoids: identical dietary provision of carotenoids in the maternal feeds resulted in the chicken eggs displaying between 1E4 and 1E9 times the concentration in the yolk than was observed for the other three species. These di†erences between the species regarding the levels of a-tocopherol and carotenoids in the yolk were closely reNected in the subsequent concentrations of these components in the livers of the hatchlings. Thus, the concentrations of a-tocopherol and carotenoids in the liver of the day-old chicken were respectively about three and two times greater than in the livers of the other three species. Although the water-soluble antioxidant, ascorbic acid, is synthesised by the embryo as opposed to provision via the maternal diet and the yolk, the concen- tration of this component in the brain of the day-old chicken was approximately 50% greater than in the brains of the other three species. Thus, it is possible that the antioxidant capacity of the developing turkey, duck and goose may be com- promised under conditions of commercial production. All four species displayed a rapid depletion of a-tocopherol and carotenoids from the livers during the -rst 9 days after hatching. 1998 SCI. (

Changes in the proportions of the various lipid components in spermatozoa were investigated throughout the reproductive period (24-72 wk of age) of male chickens. Sperm motility and in vivo fertility were also measured, and correlation coefficients with the lipid values were determined. The proportion of total phospholipid (PL) increased to reach a maximum value at 39 wk and decreased significantly thereafter. The relative content of free cholesterol and triacylglycerols showed no change in spermatozoa during aging or in relation to fertility values; free fatty acids and cholesterol esters increased continuously with age. Of the various PL classes, phosphatidylserine and phosphatidylcholine displayed a pattern of changes with age positively and negatively, respectively, in relation to the changes of fertility. The proportion of phosphatidylethanolamine had significantly decreased by the end of the reproductive period. The proportions of C16:0, C18:0, and C18:1 n-9 within the PL of the spermatozoa increased with age, and those of C20:4n-6, C22:4n-6, and C22: 6n-3 decreased. Positive correlations were found between fertility and total PLs, phosphatidylserine, and PL-bound C20:4n-6 and C22:4n-6; a negative correlation was found between fertility and phosphatidylcholine. Motility was positively correlated with the level of PL and negatively with that of free cholesterol; it was also positively correlated with the levels of C22:4n-6 and C22:6n-3 and negatively with those of C16:0, C18:0, and C18: ln-9. The results suggest that the lipid and fatty acid compositions of spermatozoa may be important predictors of fertility.

The effect of a range of concentrations of α-tocopherol in the initial yolk on the subsequent levels of this vitamin in the tissues of the newly hatched chick was investigated. Four batches of fertile eggs (Ross I broiler-breeder type) with mean yolk α-tocopherol concentrations (μg g -1 yolk) of 60.8, 155 3, 272.2 and 376.6 were incubated and the levels of the vitamin in the liver, brain, heart and kidney of the resultant chicks were measured. The liver of the day-old chick contained far higher levels of the vitamin than were found in the other tissues studied. The concentration of α-tocopherol in the liver was directly proportional to the initial level of this vitamin in the yolk. The concentrations of α-tocopherol in the brain were only about 1% of the corresponding liver values but were also directly proportional to the levels initially present in the yolk. The concentrations of α-tocopherol exhibited by the heart and kidney were affected by the initial yolk values but the response was not linear over the range of yolk α-tocopherol concentrations studied. The results indicate that the initial concentration of α-tocopherol in the yolk has a profound effect on the subsequent levels of this vitamin in the tissues of the chick. In a separate experiment, the changes in the concentration of α-tocopherol in the liver were studied over the first 9 days after hatching. The vitamin was found to be rapidly depleted from the liver after hatching.

The fatty acid composition of the plasma free fatty acid and adipose tissue triacylglycerol fractions was determined in lean and fat selection lines of Texel-Oxford and Scottish Blackface sheep at the 6th year of divergent selection. The mean proportion of 18[ratio ]2n-6 in the triacylglycerol of subcutaneous backfat was 1·3-fold higher in the phenotypically fatter sheep in the fat lines than in the phenotypically leaner sheep in the lean lines. Regression analysis indicated a positive relationship between this fatty acid and backfat depth whereas the proportion of 18[ratio ]1n-9 in the tissue triacylglycerol was negatively related to fatness. The proportions of 18[ratio ]2n-6 and of other polyunsaturated fatty acids in the plasma free fatty acid fraction were much higher than in adipose triacylglycerol. For the Scottish Blackface sheep in the fed state, the mean proportion of 18[ratio ]2n-6 in plasma free fatty acid (measured on all sheep) was 1·4-fold greater in the fat line than in the lean line. Regression analysis indicated a positive relationship between the plasma content of this fatty acid and backfat thickness whereas the proportion of 18[ratio ]1n-9 in plasma free fatty acid showed a negative relationship with fatness. The relationship between the plasma proportion of 18[ratio ]2n-6 and fatness was not observed after 48 h of fasting; instead, the plasma proportion of 18[ratio ]0 was found to be positively related to fatness in the fasted state. In summary, this paper shows how plasma and adipose tissue fatty acid profiles differ, and it quantifies the effects of selection on the plasma profiles. Possible reasons for the difference in fatty acid profiles between adipose tissue and plasma are discussed in the paper. It is suggested that plasma 18[ratio ]2n-6 levels during the early post-weaning growth period should be investigated as indicators of future fatness.

The lipid compositions and associated antioxidant capacities of spermatozoa and seminal plasma from bulls were examined at the beginning, middle and end of their reproductive period. The reduction in concentration and motility of spermatozoa associated with ageing was accompanied by a large decrease in lipid concentrations within the seminal plasma; this change in lipid concentration was accompanied by an increase in the proportion of phospholipid. By contrast, the proportion of phospholipids in the spermatozoa was significantly reduced. The major phospholipid fractions within both the spermatozoa and seminal plasma were phosphatidyl choline and phosphatidyl ethanolamine. With increasing age there was a large decrease in the proportion of phosphatidyl ethanolamine and a commensurate increase in that of phosphatidyl choline within the spermatozoa and seminal plasma. These major changes in phospholipids were accompanied by a decrease in the amount of phosphatidyl inositol and an increase in that of cardiolipin in both spermatozoa and seminal plasma. The reductions in the proportions of phosphatidyl ethanolamine were accompanied by extensive reductions in the content of the major polyunsaturated fatty acids, arachidonic 20:4 (n-6) and docosahexaenoic 22:6 (n-3); there was a decrease also in the concentration of 22:6 (n-3) in phosphatidyl choline. The changes in lipid composition owing to ageing were associated with a marked reduction within the seminal plasma of the major antioxidant enzyme systems, glutathione peroxidase and superoxide dismutase.

Although substantial information is available regarding the fatty acid composition of lipids of the yolk and of the developing tissues of the chicken embryo, there is little knowledge on this topic for other avian species. The aim of the present study was to compare the yolk and embryonic tissue fatty acid profiles for a species selecting its food in the wild (the lesser black backed gull) with one fed on a standard commercial diet (the commercially reared pheasant). The fatty acid compositions of the yolk lipids were determined, and major differences were observed between the two species. In particular, the phospholipid of the gull yolk was enriched in 20:4n-6 and 22:6n-3 (18.8 and 7.1%, respectively, by weight of total fatty acids) in comparison with the pheasant (4.0 and 4.1%, respectively). The fatty acid compositions of the embryonic tissues were determined using eggs incubated in the laboratory. For the liver and heart, the fatty acid composition of the lipids in the two species reflected the initial yolk composition, with the gull tissue lipids generally containing higher proportions of 20:4n-6 and 22:6n-3 than those of the pheasant. In contrast, the fatty acid profiles of the brain phospholipid were essentially identical in the two species, with 20:4n-6 and 22:6n-3 comprising approximately 9 and 17%, respectively, of total fatty acids in both cases.

A comparative study has been made of the major lipid fractions and their fatty acid compositions in the yolk of eggs from ostriches under wild and farmed conditions. There were no differences in the lipid contents and proportions of the lipid fractions between the two groups of yolks. In both groups of yolks triacylglycerol and phospholipid were the major fractions. In the eggs from the wild ostriches, all the lipid fractions displayed substantial concentrations of C18 polyunsaturated fatty acids, triacylglycerol being particularly rich in linolenic acid and phospholipid rich in linoleic acid; phospholipid displayed substantial concentrations also of C20 and C22 polyunsaturates. There were considerable differences in the fatty acid compositions between the yolks. Those from the farmed birds displayed lower proportions of C18 polyunsaturates, particularly linolenic acid, throughout the lipid fractions. Compensatory increases were displayed most obviously in the concentrations of oleic acid and palmitoleic acid as well as other acids. The distinctive and extensive changes in fatty acid composition, particularly relating to the polyunsaturates, are discussed with respect to overall dietary requirements and specificities for embryo metabolism and possible effects on reproductive performance.

Connection between ageing and some tissue antioxidant parameters have been studied in four experiments on different animal species. Prenatal studies on the developing chick embryos showed discrepancies between the lipid-rich liver and brain antioxidant defence. In the liver, high levels of reduced glutathione (GSH), vitamins A and E and high activities of the antioxidant enzymes glutathione peroxidase (GPX) and superoxide dismutase (SOD) were found whereas brain expressed a high vitamin C concentration. In newborn healthy calves during the first two days of life, atmospheric oxygen tension did not cause either increased lipid peroxidation as reflected in a high malondialdehyde (MDA) level or any changes in GSII, GPX, SOD and catalase (CAT) activities in red blood cells (RBC). Plasma vitamin E and carotene concentrations also did not change. In growing healthy calves during two months after birth increasing MDA, decreasing GSH, GPX and CAT are leading features, whereas plasma vitamin E and carotene concentrations significantly increased. In young (1-year-old) and old (9-year-old) dogs RBC results showed significant differences with the highest MDA and lowest GSH levels in the old males. Activity of GPX and SOD was higher in old dogs than in the young ones, especially in the females.

The concentrations of vitamin E, vitamin A, selenium, reduced glutathione and the activities of glutathione peroxidase and superoxide dismutase were determined in the yolk, yolk sac membrane, liver and brain of the developing chick embryo. The changes in the concentrations of vitamins E and A in the yolk and liver during development were consistent with the occurrence of a preferential transfer of vitamin A from the yolk to the embryo before day 14 of incubation, whereas the main period of vitamin E transfer occurred later, during the last week of incubation. The concentrations of reduced glutathione in the yolk sac membrane, liver and brain were similar at all developmental stages studied. However, the levels of the other measured antioxidant systems were very much higher in the liver than in the brain. Thus, in the newly hatched chick, the levels of vitamin E, vitamin A, selenium, glutathione peroxidase and superoxide dismutase were, respectively, 58.0-, 174.7-, 3.6-, 4.0- and 4.7- fold higher in the liver than in the brain when expressed on the basis of tissue fresh weight.

Adipocyte dimensions of subcutaneous fat, sampled by biopsy at the 13th rib, were measured in 20-week-old rams from lines of Texel-Oxford and Scottish Blackface sheep, both divergently selected for carcass lean content. A total of 163 animals were measured, with close to equal numbers per breed-line combination. In both breeds, the high (lean) selection line had significantly lower backfat depths (0·71 mm in the Texel-Oxford and 0·83 mm in the Scottish Blackface, s.e.d. = 0·14 and 0·13 mm, respectively), but body weight did not differ between the lines. The ultrasonic fat depth differences between the Texel-Oxford selected lines were accompanied by increases in adipocyte diameter, area, diameter standard deviation within each sample and implied cell number, calculated as the ratio of ultrasonic fat depth to average adipocyte diameter. In the Scottish Blackface sheep there were no selection line differences in adipocyte dimensions, but there was an increase in implied cell number in the line selected for increased fatness. Across breeds, ultrasonic fat depth was correlated with both adipocyte diameter and implied adipocyte number (r = 0·58 and 0·75, respectively), but these latter two measurements were uncorrelated with each other.

Fertile eggs obtained from alligators reared in captivity typically exhibit high rates of embryonic mortality. Also, the fatty acid composition of the yolk lipid of the captive eggs is markedly different from that observed in eggs from wild alligators, possibly as a result of differences in maternal diet in the two situations. The fatty acid compositions of tissue lipids during the embryonic development of wild and captive alligators were compared. The lipids of liver, adipose tissue and heart of the two types of embryo displayed fatty acid profiles which generally reflected the acyl compositions of the respective yolks. Thus the lipids from these tissues of the captive embryos contained markedly higher proportionate levels of linoleic and linolenic acids, lower levels of palmitoleic acid, and, in general, lower levels of docosahexaenoic acid and other C20 and C22 polyunsaturates, in comparison to the values for the wild embryos. In contrast, the fatty acid composition of the brain phosphoglycerides was very similar in the two types of embryo. Thus, at least in those embryos which had survived during the developmental period studied, the brain was able to maintain a relatively constant fatty acid composition, in spite of major differences between the wild and captive eggs in the proportions of the various fatty acids supplied from the yolk. It is suggested that a major cause of embryonic mortality in the captive embryos could be a failure to maintain an adequate level of docosahexaenoic acid in the developing brain.