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Egg Weight (egg + weight)
Selected AbstractsNuptial food gifts influence female egg production in the scorpionfly Panorpa cognataECOLOGICAL ENTOMOLOGY, Issue 3 2007LEIF ENGQVIST Abstract 1.,Before copulation, male Panorpa cognata scorpionflies offer females a salivary secretion, which is consumed by the female during copulation. It has previously been demonstrated that this nuptial food gift functions as mating effort by increasing male attractiveness and by increasing ejaculate transfer during copulation. 2.,In this study, the effect of saliva consumption on female reproductive output was investigated, and thus the possibility that nuptial food gifts also serve as paternal investment. The experimental design enabled the effect of nuptial gift consumption to be disentangled from other possible effects of multiple mating or increased copula duration. 3.,The results showed that saliva consumption increases female egg production by on average 8% (4.5 eggs) per consumed salivary mass, whereas mean egg weight was not influenced.4. These results have important implications for the evolution and maintenance of both male nuptial gifts and female polyandry in this and other species. [source] Developmental effects of bioaccumulated selenium in eggs and larvae of two salmonid speciesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2005Jodi Holm Abstract Elevated concentrations of Se have been detected in cold, flowing water habitats near uranium and coal mines in Canada. Fish from these systems have concentrations of Se in their tissues that exceed toxic effect thresholds that have been established for warm-water fishes. However, the applicability of toxic effect thresholds and guidelines to cold water, lotic habitats is a matter of contention in the literature since most cases of Se toxicosis have been documented in standing, warm-water systems. To examine the possibility of impaired reproduction in wild rainbow trout (Oncorhynchus mykiss) and brook trout (Salvelinus fontinalis) near coal mining activity in the northeastern slopes region of Alberta, Canada, spawn from both species were collected from exposure and reference sites. Gametes were fertilized in the laboratory, reared to the swim-up stage, and examined for deformities. A significant relationship was observed for rainbow trout between the amount of Se in eggs and the incidence of developmental abnormalities, specifically craniofacial defects, skeletal deformities, and edema. These associations approximate exponential functions with probabilities that 15% of the population would be affected occurring between 8.8 and 10.5 ,g Se per gram of wet egg weight, based on probit analysis. These relationships are similar to those described for centrarchids inhabiting a seleniferous warm-water lake. No such relationships were established for brook trout. [source] COMPARATIVE PHYLOGENETIC ANALYSIS OF THE EVOLUTION OF SEMELPARITY AND LIFE HISTORY IN SALMONID FISHESEVOLUTION, Issue 5 2002Bernard J. Crespi Abstract The selective pressures involved in the evolution of semelparity and its associated life-history traits are largely unknown. We used species-level analyses, independent contrasts, and reconstruction of ancestral states to study the evolution of body length, fecundity, egg weight, gonadosomatic index, and parity (semelparity vs. degree of iteroparity) in females of 12 species of salmonid fishes. According to both species-level analysis and independent contrasts analysis, body length was positively correlated with fecundity, egg weight, and gonadosomatic index, and semelparous species exhibited a significantly steeper slope for the regression of egg weight on body length than did iteroparous species. Percent repeat breeding (degree of iteroparity) was negatively correlated with gonadosomatic index using independent contrasts analysis. Semelparous species had significantly larger eggs by species-level analysis, and the egg weight contrast for the branch on which semelparity was inferred to have originated was significantly larger than the other egg weight contrasts, corresponding to a remarkable increase in egg weight. Reconstruction of ancestral states showed that egg weight and body length apparently increased with the origin of semelparity, but fecundity and gonadosomatic index remained more or less constant or decreased. Thus, the strong evolutionary linkages between body size, fecundity, and gonadosomatic index were broken during the transition from iteroparity to semelparity. These findings suggest that long-distance migrations, which increase adult mortality between breeding episodes, may have been necessary for the origin of semelparity in Pacific salmon, but that increased egg weight, leading to increased juvenile survivorship, was crucial in driving the transition. Our analyses support the life-history hypotheses that a lower degree of repeat breeding is linked to higher reproductive investment per breeding episode, and that semelparity evolves under a combination of relatively high juvenile survivorship and relatively low adult survivorship. [source] Sand intake by laying hens and its effect on egg production parametersJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 4 2008J. Van Der Meulen Summary Soil intake may be the most prominent source of environmental contaminants for free range and organic hens, but there are no quantitative data concerning soil intake by domestic hens. Consumption of soil of 14,32 g a day can be estimated from literature, but such a dilution of nutrient intake seems incompatible with high productivity. In this study laying hens were fed pelleted diets with 0%, 10%, 20%, 25% and 30% of sand addition to determine its effect on productivity. Feed intake, feed and nutrient (feed minus sand) conversion ratio, egg production, egg weight and body weight gain were measured over a 4-week period. Acid insoluble ash concentration in the faeces was measured to determine the accuracy of estimating the soil ingestion by the soil-ingestion equation for wildlife as a way to determine soil ingestion of free range and organic hens under practical circumstances. The hens were able to compensate the dilution of the diet with 20%, 25% and 30% of sand by increasing their feed intake. Feed intake increased significantly and feed to egg conversion ratio decreased significantly with increasing sand levels in the diet. The nutrient to egg conversion ratio of the diet without sand tended to be worse than for the diets with sand, presumably due to the total absence of coarse material in the diet. There were no differences in egg production and egg weight between hens fed the different diets but body weight gain was significantly lower for the hens fed the diets with 20%, 25% and 30% of sand. Estimation of sand ingestion was done by the soil-ingestion equation for wildlife. Provided that the actual dry matter digestibility coefficient of the nutrient part of the diet is taken into account, estimating the soil ingestion according to the soil-ingestion equation for wildlife seems an appropriate way to determine soil ingestion for free range and organic hens under practical circumstances. [source] Successful gonadal development and maturation of tench (Tinca tinca L.) in small concrete pondsJOURNAL OF APPLIED ICHTHYOLOGY, Issue 3 2003J. M. Carral Summary The experiments were performed in a tench farm from autumn until the spawning season (June,July). Tench broodstocks from natural habitats were maintained in 25 × 6 × 1 m concrete ponds and fed on commercial trout pellets. Females and males were separated and maintained under natural photoperiod and temperature conditions at densities around 2 kg m,2. Water flow throughout was supplied at the rate of 15 L s,1. When females showed external signs of advanced gonadal development, induction of spawning was made by luteinizing hormone releasing factor (LH-RH) synthetic analogue administration at three different periods of the reproductive season (June,July). A single intramuscular injection (20 ,g kg,1 body weight) was administered to 110 mature females selected from a total of 150. The females were stripped 42 h (22°C) after hormone administration. The mean rate of stripped females to the number injected was 77%. Mean relative egg weight in relation to the weight of the stripped females was 5.61%. More than 90% of the males provided semen without hormonal induction. Differences in egg production and external egg quality were observed at different times of the spawning period. It was proven that tench maintained in small concrete tanks and fed on artificial diets were able to reach gonadal maturation. [source] Effects of dietary black cumin seed (Nigella sativa L.) on performance, egg traits, egg cholesterol content and egg yolk fatty acid composition in laying hensJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2009Professor Dr Sakine Yalç Abstract BACKGROUND: The objective of this study was to determine the effects of dietary black cumin seed on performance, egg traits, egg cholesterol content and egg yolk fatty acid composition in laying hens during a 12 week period. For this purpose a total of 160 Lohmann Brown laying hens 36 weeks of age were allocated to four dietary treatments with one control group and three treatment groups. Black cumin seed (Nigella sativa L.) was used at the level of 5, 10 and 15 g kg,1 in the diets of the first, second and third treatment groups, respectively. RESULTS: Dietary treatments did not significantly affect body weight, feed intake, egg production, egg quality characteristics and blood parameters. Diets containing 10 and 15 g kg,1 black cumin seed increased egg weight (P < 0.01), improved feed efficiency (P < 0.01) and decreased egg yolk cholesterol, saturated fatty acids (% of total fatty acid methyl esters) and the ratio of saturated to unsaturated fatty acids (P < 0.05) compared to the diet of control group. CONCLUSION: Dietary black cumin seed at the level of 10 and 15 g kg,1 had beneficial effects on egg weight, feed efficiency, egg cholesterol content and egg yolk fatty acid composition. Therefore it can be used at the level of 10 and 15 g kg,1 in the diets of laying hens. Copyright © 2009 Society of Chemical Industry [source] Effects of egg weight on egg quality characteristicsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 3 2009Ahmet, ekero Abstract BACKGROUND: The experiment was carried out with total of 270 eggs, which were collected from a brown-egg layer strain of Lohmann hens reared in a cage system. Collected eggs were categorized according to weight and classified as medium, large, extra-large or jumbo. The purpose of the study was to determine the effect of egg weight on egg quality characteristics. RESULTS: The darkest shell color scales were noted in jumbo eggs. The redness of egg shell color in the medium egg was significantly lower than that of the other egg sizes (P < 0.05). Egg shell thickness (P < 0.05) was highest in medium egg (0.400 mm) and lowest in extra-large egg (0.382 mm). Albumen height (AH) was significantly affected by egg weight (EW) (P < 0.01). Yolk height (YH) and yolk index (YI) increased with egg size. Breaking strength was highest in the medium-weight egg. There were significant positive correlations between EW and AH, EW and YH, EW and YI, EW and yol color, EW and redness (a), but EW had significant negative correlations with ST in overall eggs. CONCLUSION: The darkest shell color (L - a - b) was noted in the jumbo egg. Albumen height and yolk height increased with egg weight. Increase in egg weight caused darkness in the yolk color scale. Copyright © 2008 Society of Chemical Industry [source] The influence of different single dietary sources on moult induction in laying hensJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2007Behzad Mansoori Abstract An investigation was carried out to assess the possibility of using single dietary sources as alternatives to feed deprivation for the induction of moult in commercial laying hens. The study involved six dietary groups of 29 laying hens: unmoulted, dried tomato pomace, alfalfa meal, rice bran, cumin seed meal and feed withdrawal. The birds received the above diets during the moulting period (11 days), and body weight loss and ovary weight regression were measured. Post-moult production parameters (number of eggs produced per hen per day, egg weight, shell weight, yolk colour and Haugh unit) were measured for 12 weeks. Results showed that all dietary sources were as effective as feed withdrawal in causing ovary weight regression in birds. Birds provided with tomato pomace or alfalfa showed lower weight losses than feed-deprived birds at the end of the moulting period. Hens moulted by tomato pomace or alfalfa exhibited post-moult levels of egg production over a 12 week period that were superior to those of hens moulted by feed withdrawal. Post-moult eggs laid by hens moulted by all dietary sources were of comparable quality to eggs from feed-deprived hens and superior to those from unmoulted hens. As fibrous feeds with low metabolisable energy and an appreciable amount of protein, dried tomato pomace and alfalfa meal may be fed to hens on an ad libitum basis for effective moult induction while reducing the stress of severe starvation and retaining comparable egg quality and production. Copyright © 2007 Society of Chemical Industry [source] Dose,response feeding study of short chain chlorinated paraffins (SCCPs) in laying hens: Effects on laying performance and tissue distribution, accumulation and elimination kineticsMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 2 2007Karl-Heinz Ueberschär Abstract Technical short chain chlorinated paraffins (C10,C13 with 60% chlorine) were fed to 93 laying hens from 24 to 32 weeks of age in increasing concentrations of up to 100 mg/kg feed. No significant influence on health, relative organ weights or performance (laying intensity, egg weight, feed consumption) was noted. The chlorinated paraffin content of the tissues was linearly related to the concentration of short chain paraffins of the feed. The highest concentrations were found in abdominal fat, egg yolk and fatty tissues. Breast muscle, egg albumen and bile fluid contained minimal or no residues. Less than 1% of the chlorinated paraffins ingested were incorporated into the body (without head, feet, gut and feathers), whereas about 1.5% were eliminated with the egg yolk and 30% were excreted with urine and faeces. A six-week kinetic depuration study revealed a biphasic elimination with half-lifes of 4,40 min (liver, kidneys, legs, fat, blood) for the initial rapid phase, and 15,30 days (blood, fat, liver, yolk, kidneys, legs) for the terminal slow phase. [source] Competition strategies and correlated selection on responses to polyandry in the seed beetle Callosobruchus maculatusPHYSIOLOGICAL ENTOMOLOGY, Issue 4 2008RAUL NARCISO C. GUEDES Abstract Polyandry reflected in multiple mating with different mates is regarded as favoured by natural selection in males but not necessarily in females, where conflicting effects on fitness components can occur. The present study aims to provide empirical evidence to predict which fitness components may be affected in this sexual conflict using a species that demonstrates potential between-population variation in their resolution: the cowpea weevil Callosobruchus maculatus. Two strains showing contrasting competition outcomes (scramble × contest) and contrasting life-history strategies based on trade-offs between longevity and fecundity are crossed for subsequent selection based on larval-competition strategy, expecting the production of a correlated response to multiple (polyandrous) mating. Such a response is expected because the scramble strain shows high fecundity (and lower longevity) and would benefit from multiple mating, in contrast with the contest strain, which shows high juvenile mortality. The scramble-selected lines would evolve a response of increased fecundity and reduced longevity under multiple and potentially polyandrous mating but the contest-selected lines would not respond to multiple (polyandrous) mating. Instead, both scramble- and contest-selected lines show increased fecundity and reduced longevity with multiple (polyandrous) matings, which did not affect egg weight. Indirect benefits of multiple (polyandrous) mating appear to be relevant for lines showing contest competition among juveniles. [source] Adult female crickets, Gryllus texensis, maintain reproductive output after repeated immune challengesPHYSIOLOGICAL ENTOMOLOGY, Issue 2 2007KELLY L. SHOEMAKER Abstract Both immunity and reproduction are thought to be energetically costly and therefore likely to make trade-offs with one another. To assess whether increasing immune system activity results in a decline in egg production, the immune system in the cricket Gryllus texensis is activated over a period of 12 days with regular injections of lipopolysaccharide (LPS) derived from Serratia marcescens, and the number of eggs laid during this time counted. Egg quality is also assessed by measuring total protein of eggs laid, fertilization and hatching success, and the weight of individual eggs laid after the series of injections. Indirect evidence suggests that LPS induces an immune response in G. texensis. However, the number of eggs produced is not affected. There is also no effect of repeated LPS injections on female weight, egg protein content, or fertilization and hatching success. Taken together, these results suggest that with food and water provided ad libitum, females can protect many aspects of fitness in the face of increased immune system activity. However, there is some evidence to suggest that large (100 ,g) doses of LPS lead to reduced female longevity, and also in egg weight that could affect offspring success. Although the possibility exists that the decline in lifespan and egg weight after high-dose injections reflects a trade-off between reproduction and immune investment, another possibility is that these doses yield nonspecific effects, or that the high-dose induces an overwhelming immune response that leads to self-damage. [source] Mapping of quantitative trait loci affecting eggshell quality on chromosome 9 in an F2 intercross between two chicken lines divergently selected for eggshell strengthANIMAL GENETICS, Issue 5 2009H. Takahashi Summary Broken and cracked eggshells are major causes of significant economic losses to the egg production industry. The quantitative trait loci (QTL) on chromosome 9 influencing the quality of eggshells were identified by analysing an intercross between two parent lines developed from the same founder population by a two-way selection for eggshell strength with non-destructive deformation conducted over 14 generations. Chromosome-wide highly significant (P < 0.01) QTL associated with egg weight (EW), short length of egg (SLE), long length of egg (LLE) and eggshell weight were mapped to the distal region of chromosome 9. Among the QTL affecting EW, SLE and LLE, ovocalyxin-32 was identified as a potential candidate gene influencing eggshell traits. Marker-assisted selection based on these QTL could be used to develop strategies for reducing the breakage and cracking of eggs in commercial layer houses. [source] Effect of dietary dried milky sludge on productive performance and egg quality in laying Japanese quailsANIMAL SCIENCE JOURNAL, Issue 3 2009Tawadchai SUPPADIT ABSTRACT The experiment was conducted to study the effectiveness of dried milky sludge (DMS) as a feed source for laying Japanese quails. The DMS was incorporated into the experimental diets at levels of 0, 5.0, 10.0, 15.0 and 20.0%. Four hundred quails were used in a completely randomized design. The results revealed that the daily egg-laying rate, feed cost/100 egg weight, egg width, egg length, egg weight, shell quality characteristics in terms of breaking time, Young's modulus, work, max force, fracturability, breaking stress, stiffness and power, as well as color intensity and yolk height improved significantly with increasing levels of DMS in the diet (P < 0.05), while feed intake/bird/day, mortality and eggshell thickness showed no significant differences (P > 0.05). From this experiment, it was found that DMS incorporated into the experimental diet at the 20.0% level yielded the most productive performance and best egg quality. [source] Effects of feeding fermented fish on egg cholesterol content in hensANIMAL SCIENCE JOURNAL, Issue 1 2009Teck-Chwen LOH ABSTRACT This study was conducted to investigate the effects of feeding fermented fish (FF) to layers on laying performance, and polyunsaturated fatty acid and cholesterol levels in eggs and plasma. A total of 96, 13-week-old Babcock B380 pullets were used in this study. They were randomly assigned to four numerically equal groups with eight replicates per treatment, three birds per replicate. All the birds were housed in individual cages. The dietary treatments were: Control diet, without FF; FF3 diet containing 3% (w/w) FF, FF6 diet containing 6% (w/w) FF and FF9 diet containing 9% (w/w) FF. The study was carried out for 16 weeks inclusive of two weeks of adjustment. Weekly feed intake and egg production were recorded. Blood plasma cholesterol and fatty acid profiles were assayed at the end of the experiment. FF did not enhance (P > 0.05) egg mass but (P < 0.05) decreased egg weight slightly. However, egg yolk cholesterol and plasma cholesterol concentrations were reduced (P < 0.05) by FF. The n-6:n-3 fatty acids ratio in the egg yolk (Control = 7.9, FF9 = 6.2) and plasma (Control = 10.6, FF9 = 6.2) were decreased by feeding FF. Moreover, FF was able to increase (P < 0.05) the docosahexaenoic acid (DHA) concentrations in egg yolk and plasma. In conclusion, this study demonstrated that FF increased DHA and reduced egg yolk cholesterol in poultry eggs. [source] | ||||||||||