scholarly journals Individual and Resource-Dependent Variation in Ability to Lay Supranormal Clutches in Response to Egg Removal

The Auk ◽  
2003 ◽  
Vol 120 (2) ◽  
pp. 481-489
Author(s):  
Tony D. Williams ◽  
Melinda Miller
Keyword(s):  
Clutch Size ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Egg Laying ◽  
Interindividual Variation ◽  
Egg Mass ◽  
Systematic Change ◽  
High Quality ◽  
Quality Diet ◽  
Egg Removal

Abstract We investigated individual and resource-dependent variation in ability of female Zebra Finches (Taeniopygia guttata) to lay supranormal clutches in response to egg removal, and effect of continuous laying on (1) egg composition and (2) plasma yolk precursor levels. Egg removal significantly increased the number of eggs that individual females laid, but that response was diet-dependent: on a high-quality (egg-supplemented) diet, females laid 12.4 ± 1.0 more eggs compared with their pretreatment clutch size; whereas on the low-quality (seed-only) diet, females laid only 4.9 ± 1.2 more eggs. Removal clutch size (i.e. total number of eggs laid in response to egg removal) was positively correlated with pretreatment mean egg mass and clutch size on the low-quality diet, but not on the high-quality diet. That suggests that there is interindividual variation in egg-laying ability (“large-egg” females had a greater capacity to respond to egg removal than “small-egg” females), but that higher resource levels can overcome individual differences. Egg mass did not vary with laying sequence in supra-normal clutches (up to 22 eggs); however, there was a significant decrease (6%) in yolk protein content of additional eggs that was apparent by the tenth egg laid (i.e. only 4–5 more than the normal clutch size). Plasma levels of the two yolk precursors, vitellogenin and very-low-density lipoprotein (VLDL), were independent of diet and did not differ in individual birds at the 1 egg stage versus the 14 egg stage. However, there was a systematic change in relationship between yolk lipid content and plasma VLDL levels, from nonsignificant for third-laid eggs to significant and positive for sixteenth-laid eggs. We propose a possible mechanism linking female condition and egg-laying ability: good quality females, capable of laying extended clutches, are able to maintain production of generic VLDL for their own metabolic needs, as well as producing yolk-targeted VLDL, whereas poor quality females are not.

scholarly journals Reproductive suppression in female cooperatively breeding cichlids

2008 ◽  
Vol 4 (6) ◽  
pp. 606-609 ◽  
Author(s):  
Dik Heg
Keyword(s):  
Clutch Size ◽  
Group Living ◽  
Egg Laying ◽  
Alloparental Care ◽  
Large Female ◽  
Egg Mass ◽  
Small Female ◽  
Reproductive Suppression ◽  
Cooperatively Breeding ◽  
Female Subordinate

Suppression by dominants of female subordinate reproduction has been found in many vertebrate social groups, but has rarely been shown experimentally. Here experimental evidence is provided for reproductive suppression in the group-living Lake Tanganyika cichlid Neolamprologus pulcher . Within groups of three unrelated females, suppression was due to medium- and small-sized females laying less frequently compared with large females, and compared with medium females in control pairs. Clutch size and average egg mass of all females depended on body size, but not on rank. In a second step, a large female was removed from the group and a very small female was added to keep the group size constant. The medium females immediately seized the dominant breeding position in the group and started to reproduce as frequently as control pairs, whereas clutch size and egg mass did not change. These results show that female subordinate cichlids are reproductively capable, but apparently suppressed with respect to egg laying. Nevertheless, some reproduction is tolerated, possibly to ensure continued alloparental care by subordinate females.

scholarly journals Reproductive traits of the gray ratsnake Ptyas korros from three geographically distinct populations

2012 ◽  
Vol 58 (6) ◽  
pp. 820-827 ◽  
Author(s):  
Long-Hui Lin ◽  
Fei Mao ◽  
Ce Chen ◽  
Xiang Ji
Keyword(s):  
Clutch Size ◽  
Egg Size ◽  
Reproductive Output ◽  
Reproductive Traits ◽  
Egg Laying ◽  
Laying Date ◽  
Egg Mass ◽  
Size Number ◽  
Female Reproductive Traits ◽  
Clutch Mass

Abstract We collected gravid gray rat snakes Ptyas korros from three geographically distinct populations in China, Chenzhou (CZ), Jiangshan (JS) and Dinghai (DH), to study geographical variation in female reproductive traits. Egg-laying dates differed among the three populations such that at the most northern latitude egg-laying was latest, and earliest at the most southern lati-tutde. Clutch size, clutch mass, egg mass, egg shape, within clutch variability in egg sizes and relative clutch mass differed among the three populations, whereas post-oviposition body mass did not. Except for egg-laying date, none of the traits examined varied in a geographically continuous trend. CZ and DH females, although separated by a distance of approximately 1100 km as the crow flies, were similar in nearly all traits examined. JS females were distinguished from CZ and DH females by their higher fecundity (clutch size), greater reproductive output (clutch mass) and more rounded eggs. Our data do not validate the prediction that larger offspring should be produced in colder localities. The absence of an egg size-number trade-off in each of the three populations presumably suggests that P. korros is among species where eggs are well optimized for size within a population.

scholarly journals Dietary carotenoid supplementation facilitates egg laying in a wild passerine

2019 ◽  
Author(s):  
Jorge García-Campa ◽  
Wendt Müller ◽  
Sonia González-Braojos ◽  
Emilio García-Juárez ◽  
Judith Morales
Keyword(s):  
Embryonic Development ◽  
Clutch Size ◽  
Egg Production ◽  
Egg Quality ◽  
Antioxidant Properties ◽  
Egg Laying ◽  
Egg Mass ◽  
Blue Tit ◽  
Trade Off ◽  
Dietary Carotenoid

During egg laying, female birds face a trade-off between self-maintenance and investment into current reproduction. Providing eggs with resources is energetically demanding, since in most species females lay one egg per day. However, the costs of egg laying not only relate to energetic requirements, but also depend on the availability of specific resources that are vital for egg production and embryonic development. One of these compounds are carotenoids, pigments with antioxidant properties and immuno-stimulatory functions, which are crucial during embryonic development. In this study, we explore how carotenoid availability alleviates this trade-off and facilitates egg laying in the blue tit. Blue tit females lay one egg per day and have the largest clutch size of all European passerines. We performed a lutein supplementation experiment, and measured potential consequences for egg laying capacity and egg quality. We found that lutein-supplemented females had less laying interruptions and thus completed their clutch faster than control females. No effects of treatment were found on the onset of egg laying or clutch size. Experimentally enhanced carotenoid availability did not elevate yolk carotenoid levels or egg mass, but negatively affected eggshell thickness. Our results provide hence evidence on the limiting role of carotenoids during egg laying, However, the benefits of laying faster following lutein supplementation were counterbalanced by a lower accumulation of calcium in the eggshell. Thus, even though single components may constrain egg laying, it is the combined availability of a range of different resources which ultimately determines egg quality and thus embryonic development.

scholarly journals Comparative Effects of Flaxseed Sources on the Egg ALA Deposition and Hepatic Gene Expression in Hy-Line Brown Hens

Foods ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1663
Author(s):  
Muhammad Suhaib Shahid ◽  
Tausif Raza ◽  
Yuqin Wu ◽  
Mazhar Hussain Mangi ◽  
Wei Nie ◽  
...  
Keyword(s):  
Gene Expression ◽  
Egg Production ◽  
Laying Hens ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Egg Yolk ◽  
Lipoprotein Cholesterol ◽  
Egg Mass ◽  
Low Density ◽  
Low Density Lipoprotein Cholesterol

Healthy diets are necessary for both humans and animals, including poultry. These diets contain various nutrients for maintenance and production in laying hens. Therefore, research was undertaken to explore the efficiency of various dietary flaxseed sources on the n-3 deposition in the egg yolk and gene expression in laying hens. Five dietary groups were analyzed, i.e., (i) a corn-based diet with no flaxseed (FS) as a negative control (NC), (ii) a wheat-based diet supplemented with 10% whole FS without multi-carbohydrase enzymes (MCE) as a positive control (PC), (iii) ground FS supplemented with MCE (FS), (iv) extruded flaxseed meal was supplemented with MCE (EFM), (v) flaxseed oil supplemented with MCE (FSO). Results indicated that egg weight was highest in the NC, FS, EFM, and FSO groups as compared to PC in the 12th week. Egg mass was higher in enzyme supplemented groups as compared to the PC group, but lower than NC. In the 12th week, the HDEP (hen day egg production) was highest in the FS and EFM groups as compared to FSO, PC, and NC. The FCR (feed conversion ratio) was better in enzyme supplemented groups as compared to the PC group. Enzyme addition enhanced the egg quality as compared to PC in the 12th week. The HDL-C (high-density lipoprotein cholesterol) was increased, while LDL-C (low-density lipoprotein cholesterol), VLDL-C (very-low-density lipoprotein cholesterol), TC (total cholesterol), and TG (total triglycerides) were reduced in the enzyme supplemented groups as compared to PC and NC. The FSO deposit more n-3 PUFA and docosahexaenoic acid (DHA) in the egg yolk as compared to FS and EFM groups. The expression of ACOX1, LCPT1, FADS1, FADS2, and ELOV2 genes were upregulated, while PPAR-α was downregulated in the FSO group. The LPL mRNA expression was upregulated in the FS, EFM, and FSO groups as compared to the PC and NC groups. It was inferred that FSO with enzymes at 2.5% is cost-effective, improves the hen performances, upregulated the fatty acid metabolism and β-oxidation genes expression, and efficiently deposits optimal n-3 PUFA in the egg as per consumer’s demand.

Effects of exogenous 17(β)-estradiol on the reproductive physiology and reproductive performance of european starlings (Sturnus vulgaris)

1999 ◽  
Vol 202 (19) ◽  
pp. 2679-2685 ◽  
Author(s):  
J.K. Christians ◽  
T.D. Williams
Keyword(s):  
Reproductive Performance ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Sturnus Vulgaris ◽  
Reproductive Physiology ◽  
Egg Mass ◽  
Very Low Density Lipoprotein ◽  
Estradiol Treatment ◽  
European Starlings ◽  
Egg Formation

Egg mass shows large intraspecific variation in birds and yet the mechanisms underlying this variation remain unknown. We hypothesized that estradiol would play a central role in determining egg mass, since this hormone stimulates the production of yolk precursors (vitellogenin and very-low density lipoprotein, VLDL) by the liver, and of albumen by the oviduct. We gave European starlings (Sturnus vulgaris) silastic implants containing estradiol prior to egg formation, which we predicted would increase egg mass. As expected, exogenous estradiol stimulated a marked (49 %) increase in plasma vitellogenin levels at the beginning of laying. At clutch completion, plasma VLDL levels and oviduct mass were also elevated in estradiol-treated females compared with controls. However, estradiol had no effect on fresh egg mass or clutch size. Estradiol treatment actually decreased the mass of yolk protein and lipid, perhaps by decreasing the rate of uptake of yolk precursors at the ovary. The failure of estradiol to increase egg mass indicates that this phenotype may be regulated at higher levels of organization (e.g. negative feedback, uptake of yolk precursors) than those studied in this experiment. Despite elevating yolk precursor levels, treatment with estradiol had no effect on the mass of the liver or endogenous stores of protein and lipid at clutch completion.

scholarly journals Feeding a definite concentration of eicosapentaenoic and docosahexaenoic fatty acids to laying hens

2019 ◽  
Vol 70 (1) ◽  
pp. 1393
Author(s):  
E. E. NASSEF ◽  
A. A. BAKR ◽  
A. S. SALAMA
Keyword(s):  
Fatty Acids ◽  
Egg Production ◽  
Laying Hens ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Egg Yolk ◽  
Feed Consumption ◽  
Egg Mass ◽  
Low Density ◽  
Epa And Dha

The experiment designed to study the influences of nutritional eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids (FA) on performance, egg yolk fat characteristics and FA profile in laying hens. From 30 to 36 weeks of age, 180 laying hens were allotted randomly to 2 dietary treatments, each of 6 replicates (15 birds for each replicate). The control diet was supplied with soy oil while the experimental diet was supplied with EPA and DHA to create 2 different ratio of n-6 to n-3 FA (18.8:1 and 5:1, respectively). The egg production % was recorded daily. The eggs were weighed to estimate egg mass. Also, feed consumption was recorded daily and the feed conversion ratio (FCR) was estimated. The FA profile of egg yolk was determined in the last week of the experiment. The dietary EPA and DHA resulted in significantly higher egg production (76.89 versus 67.23%), weightier egg mass (42.46 versus 37. 72 g) and lower FCR (2.49 versus 2.72) than the control. Also, supplying the dietary EPA and DHA was reflected in increasing of total polyunsaturated and n-3 FA in the eggs. Moreover, reducing the ratio of n-6 to n-3 FA to 5:1 decreased egg triglycerides, total cholesterol and cholesterol associated with low density lipoprotein and very low density lipoprotein. In conclusion, supplying EPA and DHA in the diet of laying hens positively influences performance, egg yolk FA profile and cholesterol. Practically, EPA and DHA could be used in laying hen diets to improve their performance and enhance public health of egg consumers.

scholarly journals Characterization of a Vitellogenin Receptor in the Bumblebee, Bombus lantschouensis (Hymenoptera, Apidae)

Insects ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 445 ◽  
Author(s):  
Lin Du ◽  
Mingming Wang ◽  
Jilian Li ◽  
Shaoyu He ◽  
Jiaxing Huang ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Bombus Terrestris ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Reproductive Function ◽  
Egg Laying ◽  
Expression Level ◽  
Reading Frame ◽  
Vitellogenin Receptor ◽  
Density Lipoprotein Receptor

The vitellogenin receptor (VgR) belongs to the low-density lipoprotein receptor (LDLR) family, responsible for mediating the endocytosis of vitellogenin (Vg) into the ovaries to promote ovarian growth and oviposition. Here, we cloned and measured VgR gene expression characteristics in the bumblebee Bombus lantschouensis. RNA interference was used to validate VgR function. The results showed that the full length of the BLVgR cDNA was 5519 bp, which included a 5280 bp open reading frame encoding 1759 amino acids (AAs). Sequence alignment revealed that the protein contained 12 LDLa, 5 EGF, 2 EGF-CA and 10 LY domains. Phylogenetic analysis showed that BLVgR and the VgR of Bombus terrestris clustered together and the tree of bumblebees (Bombus) appeared as one clade next to honeybees (Apis). Transcript expression analysis showed that BLVgR was expressed in all tested tissues and showed the highest abundance in the ovaries. BLVgR expression was present in all developmental stages. However, the expression level in larvae was extremely low. In addition, the expression of BLVgR was significantly upregulated after egg laying in both workers and queens. In new emerging workers injected with 5 µg of VgR dsRNA, the expression level of BLVgR was 4-fold lower than that in the GFP dsRNA-injected group after 72 h. Furthermore, BLVgR silencing significantly reduced the number of eggs laid (3.67 ± 1.96 eggs) and delayed the first egg-laying time (16.31 ± 2.07 days) in worker microcolonies when compared to dsGFP (37.31 ± 4.09 eggs, 8.15 ± 0.22 days) and DEPC-treated water injected controls (16.42 ± 2.24 eggs, 10.00 ± 0.37 days). In conclusion, the BLVgR gene and its reproductive function were explored in the bumblebee B. lantschouensis. This gene plays an important role in egg laying time and egg number.

scholarly journals Predation risk affects egg mass but not egg steroid hormone concentrations in yellow-legged gulls

2018 ◽  
Vol 65 (4) ◽  
pp. 401-408 ◽  
Author(s):  
Cristina Daniela Possenti ◽  
Alexandra Bea Bentz ◽  
Andrea Romano ◽  
Marco Parolini ◽  
Manuela Caprioli ◽  
...  
Keyword(s):  
Predation Risk ◽  
Clutch Size ◽  
Experimental Treatment ◽  
Egg Laying ◽  
Egg Mass ◽  
Reproductive Decisions ◽  
Lethal Effects ◽  
Cascading Effects ◽  
Larus Michahellis ◽  
And Behavior

AbstractPredators have both direct, consumptive effects on their prey and non-lethal effects on physiology and behavior, including reproductive decisions, with cascading effects on prey ecology and evolution. Here, we experimentally tested such non-lethal effects of exposure to increased predation risk on clutch size, egg mass, and the concentration of yolk steroid hormones in the yellow-legged gull Larus michahellis. We simulated increased predation risk by displaying stuffed predators (adult fox Vulpes vulpes, and adult buzzard Buteo buteo) to breeding adults before egg laying. The concentration of corticosterone, which has been shown to increase under exposure to maternal predation risk in other species, and of testosterone did not differ between eggs from mothers exposed to the predators and eggs from control mothers (i.e., eggs exposed to a novel object of similar size and position to the stuffed predators). The concentration of the two hormones negatively covaried. Clutch size did not vary according to experimental treatment, whereas egg mass was markedly larger in clutches from nests exposed to predators than in clutches from control nests. By increasing egg mass, mothers may reduce the risk of cooling of the eggs when incubation is impeded by predators, boost energy reserves, reduce post-natal detectability caused by food solicitation, and/or enhance development at hatching, thus increasing the chances of offspring survival. In general, our results are inconsistent with most of the few previous studies on similar non-lethal predator effects and suggest that such effects may vary among species according to ecological conditions, social behavior, and developmental mode.

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