Rapid modulation of the n-3 docosahexaenoic acid levels in the brain and retina of the newly hatched chick

The newly hatched chick obtains its fatty acids almost completely from the lipids of the egg yolk as these are transferred to the developing embryo during its 21-day period of incubation. Since the diet of the laying hen greatly influences the fatty acid composition of the egg lipids, and presumably also the fatty acid composition of the resulting chick, we tested how quickly and to what extent varying the amount of n-3 fatty acids in the diet of the hen would modulate the level of n-3 fatty acids in the brain and retina of the newly hatched chick. White Leghorn hens were fed commercial or semi-purified diets supplemented with 10% fish oil, linseed oil, soy oil, or safflower oil. Eggs, together with the brain, retina, and serum of newly hatched chicks, were then analyzed for fatty acid composition. The fatty acids of egg yolk responded quickly to the hen's diet with most of the change occurring by 4 weeks. There was a linear relationship between the linolenic acid content of the diets and levels of this fatty acid in egg yolk and chick serum. In chicks from hens fed the fish oil diet, the total n-3 fatty acids, including 22:6(n-3), were elevated twofold in the brain and retina and sevenfold in serum relative to commercial diet controls. The safflower oil diet led to a very low n-3 fatty acid content in egg yolks and only 25% of the control n-3 fatty acid content in the brain and retina of chicks.(ABSTRACT TRUNCATED AT 250 WORDS)     

Potential of alfalfa as an alternative molt induction diet for laying hens: egg quality and consumer acceptability

Dietary molt induction to initiate additional egg laying cycles in commercial laying hen flocks is a wide spread practice in the United States. Feed deprivation is the most commonly used method but this practice has generated several concerns which has lead to research for viable alternative approaches. From a management standpoint a single ingredient molting diet consisting of high fiber-low energy represents an easily adaptable diet for large laying hen production units. Alfalfa meal is readily available in most commercial locations and possesses many of the desirable properties of an ideal laying hen molt diet. In the current study hens at a commercial laying facility were molted by both alfalfa and feed deprivation. After the hens had reentered post-molt commercial egg production, eggs were examined for egg quality performance. Egg shell strength, albumen height, yolk height, weight, length, and yolk color were all tested using various mechanical techniques. The eggs were also sampled for testing by consumer sensory panels that assessed the desirability of the eggs' color and flavor/texture. Eggs laid by hens molted by alfalfa had a significantly lower (p<0.05) "a*" level of colorimetry. Eggs laid by hens molted with alfalfa also exhibited significantly higher (p<0.05) egg weights and length. In the consumer sensory test, there was no significant difference (p>0.05) in color or flavor/texture scores in eggs from either feed deprived or alfalfa molted hens. The consumer sensory and mechanical quality attributes indicates that alfalfa shows promise as an alternative molt induction diet by providing a single diet option for extending egg production into a second egg laying cycle.     

Pre-breeding diet affects the allocation of yolk hormones in zebra finches Taeniopygia guttata

The ability of mothers to modify offspring phenotype to match prevailing environmental conditions is an important component of reproductive success, especially in variable environments. Pre-breeding conditions, such as food abundance, may have significant consequences for both the number and quality of offspring a female produces as well as her ability to rear the offspring. In an experiment where pre-breeding diet was manipulated, we investigated if allocation of yolk androgens (testosterone and 5α-dihydrotestosterone) was related to the quality of diet experienced prior to breeding. Female zebra finches Taeniopygia guttata produced larger clutches on high quality diet than on low quality diet but with no differences in egg mass. Yolk androgen levels were repeatable within subsequent clutches of the same female and females did not change mean androgen content in eggs in relation to diet quality. However, within-in clutch pattern of yolk testosterone and DHT changed with diet treatment. Testosterone and DHT decreased with laying order on the low quality diet but remained constant on the high quality diet. Differential yolk androgen allocation within the clutch may alter the competitive differences between chicks and provide females the possibility to adjust reproductive investment and offspring phenotype already at the egg stage.     

Egg-size variation and reproductive success in the Herring Gull Lams argentatus: adaptive or constrained size of the last egg?

Herring Gull Larus argentatus eggs from a study colony in the Baltic showed a slight but significant variation in egg size within the laying sequence. Last-laid eggs were only about 5% smaller by volume than first eggs. There was no significant difference in dry yolk weight or dry albumen weight, although possible differences were evident. The chicks had nearly equal hatching weights and equally long tarsi. There was no differential mortality in the third chick in the study colony, and there were no indications of egg-size-mediated mortality. The birds in the colony produced an average of 1.45 fledglings per pair. Compared with several other studied colonies, the difference in egg size within a clutch was low, and a comparison of colonies from northwestern Europe suggests that variance within the clutch is negatively correlated with fledging success, so that a large difference in size between first and last eggs is associated with low fledging success. We suggest that the size of the last egg in the clutch reflects the feeding potential in the environment and is mainly a nonadaptive response to poor feeding conditions during laying.     

Maternal effects as drivers of sibling competition in a parent–offspring conflict context? An experimental test

Maternal effects occur when the mother's phenotype influences her offspring's phenotype. In birds, differential allocation in egg yolk components can allow mothers to compensate for the competitive disadvantage of junior chicks. We hypothesize that the parent–older chick conflict peaks at intermediate conditions: parents benefit from the younger chick(s) survival, but its death benefits the older chick in terms of growth and survival. We thus expect maternal compensation to follow a bell‐shaped pattern in relation to environmental conditions. We studied a black‐legged kittiwake (Rissa tridactyla) population where previous results revealed increased allocation of yolk testosterone in younger as compared to older chicks in intermediate conditions, in line with our theoretical framework. We therefore predicted a maternally induced increase in aggressiveness, growth, and survival for younger chicks born in intermediate environmental conditions. Controlling for parental effects and chick sex, we manipulated food availability before egg laying to create a situation with intermediate (Unfed group) and good (Fed group) environmental conditions. Within each feeding treatment, we further created experimental broods where the natural hatching order was reversed to maximize our chances to observe an effect of feeding treatment on the younger chicks' aggressiveness. As predicted, we found that chick aggressiveness was higher in younger chicks born from the Unfed group (i.e., in intermediate environmental conditions), but only when they were put in a senior position, in reversed broods. Predictions on growth and survival were not confirmed. Mothers thus seem to favor the competitiveness of their younger chick in intermediate conditions via egg yolk components, but our study also suggests that hatching asynchrony need to be small for maternal compensation to be efficient. We emphasize the need for further studies investigating other chick behaviors (e.g., begging) and focusing on the relative role of different yolk components in shaping parent–offspring conflict over sibling competition.     

Do mothers regulate facultative and obligate siblicide by differentially provisioning eggs with hormones?

We examined androgens in clutches of two booby species that differ in their sibling conflict. Blue-footed booby Sula nebouxii chicks show an aggression-submission relationship, aggression is normally moderate and siblicide is facultative. Brown booby Sula leucogaster chicks show an aggression-aggression relationship, aggression of both chicks can be relentless and siblicide is obligate. The parental favoritism hypothesis predicts that egg mass, yolk mass and yolk androgens should decline with laying order less in the blue-footed booby than in the brown booby, to promote the survival of the former's junior chick. The eggs of the blue-footed booby had higher yolk concentrations of 5α-dihydrotestosterone (DHT) and lower concentrations of testosterone (T); both species had similarly high yolk concentrations of androstenedione (A). Intra-clutch variation in yolk DHT, T and A failed to support our predictions. In both species, first and second eggs showed similar concentrations of all three hormones and were of similar size, although in the blue-footed booby (only) yolk masses declined with laying order. Brown booby mothers make junior chicks vulnerable to siblicide by hatching them 5 d after their broodmates, but not by differential allocation of egg androgens or nutrients. Blue-footed booby mothers appear to prepare junior chicks for thriving in a subordinate non-provocative role by hatching them 4 d after their broodmates and providing them with 10% less yolk. To orchestrate agonism within the brood, these boobies may rely more on hatch intervals and yolk provision than on androgens.     

Maternal Diet Influences Offspring Feeding Behavior and Fearfulness in the Precocial Chicken

Background

In chicken, oils in the maternal diet confer a specific scent to the yolk. Embryos are known to perceive and memorize chemosensory signals of the surrounding environment; however, the potential impact of the maternal diet has not previously been investigated. In the present study, we hypothesized that chicken embryos memorize the chemical signals of the maternal diet and that this perceptual learning may orient subsequent feeding behavior of the hatchlings.

Methodology/Principal Findings

Laying hens were fed standard food enriched with 2% menhaden oil (MH group) or 2% soybean oil (controls). The scent of menhaden was significantly more detected in MH egg yolks than in control yolks by a human panel. We analyzed the development and behavior of offspring towards different types of food, bearing or not bearing the menhaden scent. When chicks were exposed to a 3-min choice test between the familiar food bearing the menhaden scent and the familiar food without menhaden, no effect of treatment was observed. In a 3-min choice test with unfamiliar food (mashed cereals) MH chicks showed a clear positive orientation toward the unfamiliar food bearing the menhaden scent. By contrast, control chicks showed a preference for the non-odorized unfamiliar food. MH chicks expressed higher emotional reactivity level than control chicks as expressed by food neophobia and longer immobility in a restraint test.

Conclusion/Significance

Chicks exposed in ovo to menhaden oil via the maternal diet preferentially oriented their feeding behavior towards food containing menhaden oil, but only when the food was unfamiliar. We propose that oil in the maternal diet engenders maternal effects and contributes to the development of behavioral phenotype in the offspring. In ovo chemosensory learning may have evolved to prepare precocial offspring for their environment. This suggests a common principle of embryonic chemosensory learning across vertebrate taxa.     

Protective effect of modified glucomannans against aurofusarin-induced changes in quail egg and embryo

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.     

Impact of an energy- and nutrient-reduced diet containing 10% lignocellulose on animal performance,body composition and egg quality of dual purpose laying hens

In response to ethical concerns regarding the killing of day-old male chicks of layer breeds, the use of dual purpose chickens is increasingly discussed in public while data on nutritional requirements of dual purpose laying hens are not available. The present study examined the impact of an energy- and nutrient-reduced diet containing lignocellulose on performance, body composition and egg quality of dual purpose hens. Female Lohmann Dual chicks were allocated to 12 pens and fed two different diets for 52 weeks: a control (CON) and a treatment diet (LC), based on CON but diluted with 10% lignocellulose. During the trial, animal performance, whole-body composition and egg quality parameters of hens were consistently ascertained. The results showed that LC-fed hens had lower body weights compared to those receiving CON (p < 0.05). During the laying period, feed intake was increased in LC-fed hens (p < 0.001). LC-fed hens showed a higher egg production and egg mass resulting in an improved feed efficiency (p < 0.05) and laid smaller eggs compared to CON-fed hens (p < 0.001). At 52 weeks of age, bodies of LC-fed hens had higher protein and lower fat contents than those fed with CON diet (p ≤ 0.001). Mean body weight was positively correlated to the body fat content (p = 0.004) and body fat content was negatively correlated to the egg production (p = 0.043). Analyses of the egg quality showed that yolk mass at all sampling points and albumen mass at 27 and 42 weeks were lower in hens fed with diet LC compared to those fed with diet CON (p< 0.05). In conclusion, the feeding of energy- and nutrient-reduced diets containing 10% lignocellulose reduced the body fat content and simultaneously improved the laying performance in dual purpose hens.     

Transfer of Soy Isoflavone into the Egg Yolk of Chickens

A diet containing a high concentration of soy isoflavone was administered to laying hens and the contents of the isoflavones transferred to the plasma and egg yolk were measured. A method for quantitatively measuring the concentration of isoflavone in the yolk was first established, before a high concentration of soy isoflavone was administered to the laying hens over an 18-day period. The concentrations of isoflavone in the plasma and egg yolk reached their highest on the 12th day of the feeding period, the values being 3,167 nmol/l and 65.29 μg/100g, respectively. The concentration of cholesterol in the yolk was slightly affected during the early stages of the feeding period. These findings clearly demonstrate that soy isoflavone was transferred into the yolk from the feed and that the cholesterol concentration in the yolk was affected by administering the soy isoflavone-enriched feed.     

Transfer of soy isoflavone into the egg yolk of chickens.

A diet containing a high concentration of soy isoflavone was administered to laying hens and the contents of the isoflavones transferred to the plasma and egg yolk were measured. A method for quantitatively measuring the concentration of isoflavone in the yolk was first established, before a high concentration of soy isoflavone was administered to the laying hens over an 18-day period. The concentrations of isoflavone in the plasma and egg yolk reached their highest on the 12th day of the feeding period, the values being 3,167 nmol/l and 65.29 microg/100 g, respectively. The concentration of cholesterol in the yolk was slightly affected during the early stages of the feeding period. These findings clearly demonstrate that soy isoflavone was transferred into the yolk from the feed and that the cholesterol concentration in the yolk was affected by administering the soy isoflavone-enriched feed.     

Metabolism of cholesterol in the tissues and blood of the chick embryo

Three artificially inseminated laying White Leghorn hens were given 35-50 micro c of cholesterol-4-(14)C intravenously. Their subsequently produced eggs contained cholesterol-(14)C-labeled yolks. Some of the fertilized eggs were analyzed for cholesterol content and radioactivity. Other eggs were incubated until hatching. The specific activity of the cholesterol contained in the serum and tissues of newly hatched chicks was determined and compared with that of yolk sac, which was taken as representative of egg yolk cholesterol before its metabolic transfer into the chick embryo. The specific activities of cholesterol in intestine, liver, serum, heart, and skeletal muscle and the whole chick were 95-98% of that in yolk sac, but that of brain cholesterol was only 11% of this value. These results indicate that whereas most of the cholesterol in the chick originated from the egg yolk, cholesterol biosynthesis was active in the brain and provided about 90% of its cholestero content. Newly hatched chicks were found to be hyperlipemic compared with older chicks and had fatty livers with a high cholesterol content. Desmosterol was found in 9- and 15-day old chick embryos but not in the newly hatched chicks, in which the only sterol was cholesterol.     

Effects of sorghum grain tannins and dietary protein on the activity of liver UDP-glucuronyltransferase

The activity of liver microsomal UDP-glucuronyltransferase (EC 2.4.1.17), an enzyme known to detoxify phenolic compounds, was measured in chicks and rats fed high- (HTS) and low-tannin sorghums (LTS). In an initial investigation, activity was significantly elevated in chicks fed HTS-soybean meal diets over those fed the LTS control diet. Other studies were designed to differentiate between the effects due to tannin and those resulting from a protein deficiency which had previously been reported to increase the activity of this enzyme. In general, only a relatively small part of the increased activity observed by feeding HTS to chicks could be attributed to a tannin-induced protein deficiency. The same phenomenon of elevated activity produced by feeding HTS to chicks was not observed in the rat. These results would suggest that sorghum tannins, or their breakdown products, are absorbed and activating UDP-glucuronyltransferase in the chick, but not the rat.     

Diet, food availability and habitat selection of breeding Common Sandpipers Actitis hypoleucos

The diet of the Common Sandpiper, as studied by faecal analysis, includes a wide variety of prey, the majority of which are of terrestrial rather than of aquatic origin. Observation of feeding activity confirms that much time is spent feeding in grassland, although shingly river edges are also important. The feeding activity of young chicks is also largely confined to wet grassy areas, but older chicks feed almost entirely along the     

Egg size, composition and offspring quality in some Alcidae (Aves: Charadriiformes)

The composition of fresh and fully developed (pipping) eggs of four alcids, Razorbill, Common guillemot, Brünnich's guillemot and Atlantic puffin was examined. There were no differences in egg composition between the semi-precocial Atlantic puffin and the three species with "intermediate" developmental patterns. The absolute amount of yolk increased with egg size in fresh eggs, and the relative amount remained constant with egg size for Common guillemot and Razorbill, but decreased in the Atlantic puffin. In fully developed eggs chick weight and egg weight were closely correlated, and this was due mainly to larger eggs producing chicks with larger yolk reserves. Under some conditions chicks from larger eggs do better than those from smaller eggs. Several factors influence egg size; a comparison of first and replacement eggs laid by the same females showed that a maternal effect accounted for 60–90% of the variance in egg-size and that laying date accounted for most of the remaining variance.     

Differential maternal testosterone allocation among siblings benefits both mother and offspring in the zebra finch Taeniopygia guttata

Parents are selected to preferentially invest in the offspring with highest reproductive value. One mechanism for achieving this is the modification of competitive asymmetries between siblings by maternal hormones. In many organisms, offspring value varies according to birth position in the brood, which determines survival chances and competitive advantage over access to resources. In birds, variation in yolk androgen allocation over the laying sequence is thought to modulate dominance of senior chicks over junior brood mates. We tested this hypothesis in zebra finches, which show a naturally decreasing pattern of within-clutch testosterone allocation. We abolished these within-clutch differences by experimentally elevating yolk testosterone levels in eggs 2-6 to the level of egg 1, and we assessed fitness measures for junior offspring (eggs 2-6), senior offspring (egg 1), and their mothers. Testosterone-injected eggs hatched later than control eggs. Junior, but not senior, chicks in testosterone-treated broods attained poorer phenotypic quality compared to control broods, which was not compensated for by positive effects on seniors. Mothers were generally unaffected by clutch treatment. Thus, naturally decreasing within-clutch yolk testosterone allocation appears to benefit all family members and does not generally enhance brood reduction by favoring senior chicks, in contrast to the widely held assumption.     

Physiological constraints and the influence of diet on fatty acids in the yolk of gentoo penguins, Pygoscelis papua

Avian yolk fatty acids (FA) composition is influenced by two main factors: maternal diet and genetic factors that regulate FA metabolism. However, due to embryonic developmental requirements, yolk FA are thought to be physiologically constrained and less useful for dietary and trophic studies. We assessed the relative contributions of diet and physiological constraints in determining the yolk FA composition of a marine bird, the gentoo penguin (Pygoscelis papua) by comparing FA signatures of yolks and prey between a captive, controlled- feeding experiment and a wild population. Captive and wild yolk FA signatures differed even though both groups' yolk lipids were composed primarily of three FA (16:0, 18:0 and 18:1n-9). Differences were due to FA occurring in relatively low abundance, but which mirrored differences in the FA composition of diets. However, yolk FA signatures were correlated across three penguin species suggesting that common developmental constraints can be relatively more important than species-specific differences in diet or egg-laying physiology. While yolk FA are constrained, several minor components of yolk FA are reflective of diets and the calibration coefficients resulting from this study have the potential to be incorporated into predictive models and allow for quantitative dietary and trophic studies using FA analysis of penguin egg yolks.     

Maternal allocation strategies and differential effects of yolk carotenoids on the phenotype and viability of yellow-legged gull (Larus michahellis) chicks in relation to sex and laying order

Egg quality may mediate maternal allocation strategies according to progeny sex. In vertebrates, carotenoids have important physiological roles during embryonic and post-natal life, but the consequences of variation in yolk carotenoids for offspring phenotype in oviparous species are largely unknown. In yellow-legged gulls, yolk carotenoids did not vary with embryo sex in combination with egg laying date, order and mass. Yolk lutein supplementation enhanced the growth of sons from first eggs but depressed that of sons from last eggs, enhanced survival of daughters late in the season, and promoted immunity of male chicks and chicks from small eggs. Lack of variation in egg carotenoids in relation to sex and egg features, and the contrasting effects of lutein on sons and daughters, do not support the hypothesis of optimal sex-related egg carotenoid allocation. Carotenoids transferred to the eggs may rather result from a trade-off between opposing effects on sons or daughters.     

Genetic variants of phosvitin in egg yolk of the Japanese quail, Coturnix coturnix japonica

Phosvitin polymorphism in egg yolk of the Japanese quail was found by horizontal polyacrylamide gradient gel electrophoresis. Six phenotypes of yolk phosvitin designated A, B, C, AB, AC, and BC were observed in a population of 281 birds. Analysis of family data revealed that the phenotypic variation of quail yolk phosvitins was controlled by an autosomal Pv locus with three codominant alleles, Pva, Pvb and Pvc. The gene frequencies of Pva, Pvb and Pvc were 0.064, 0.824 and 0.112, respectively.