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At least 433 records · Page 24Linked to original sources
PubMed1994

Changes in functional qualities of turkey eggshells in strains selected for increased egg production or growth.

Much past research has been devoted to physical eggshell qualities, i.e., weight, deformation, or egg density, but little research has investigated the functional eggshell qualities when expressed in terms of eggshell conductance to gases. Conductance is a measure of the ease with which gases diffuse across the pores of the shell and is (by Fick's law) determined by the number and geometry of the individual pores. The objective of the present study was to determine changes that have occurred in functional eggshell characteristics (eggshell conductance) following selection for egg production or growth over nearly 30 generations. Major changes have occurred in the physical dimensions of eggs from selected lines of turkeys compared with their respective randombred controls. Egg weights increased 11% due to selection for growth and decreased 14% due to selection for egg production. Other measurements such as length and width increased allometrically with egg weights. Selection for egg production has decreased the physical dimensions (egg weight, volume, or surface area) of eggs, and selection for growth has increased the same measurements, but adjustments have not been made by selected hens to increase or decrease the functional characteristic (conductance) allometrically (conductance constants). An interaction was observed in eggshell conductance constants as the hens aged, suggesting that genetic selection may affect functional characteristics. This suggests that the energetics of embryonic development may be different in eggs from turkey hens of various ages. Energetics may result in poor hatchability and poult quality. It can be concluded that as the hens aged the conductance and conductance constants did not change allometrically with increasing egg weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2006

Egg colour reflects the amount of yolk maternal antibodies and fledging success in a songbird.

Blue-green colours in avian eggs have been proposed as post-mating signals of female phenotypic quality to their mates. Egg colour may not only indicate female value, but also the quality of the eggs themselves and of resulting offspring. To date, there has been no demonstration of an association between egg colour and egg or offspring immune quality. We here show that the intensity of blue-green colour of pied flycatcher Ficedula hypoleuca eggs reflects the amount of maternal antibodies in the yolk, a form of passive immunity crucial for offspring performance. Moreover, egg colour predicts fledging success. Also, incubating females in better condition lay more colourful eggs. The immunoglobulin level in incubating females is positively associated with that in the eggs. These results support the signalling hypothesis of eggshell coloration, underlining its role as an indicator of trans-generational transmission of immune defences in birds.

Animals↗
PubMed2000

Effects of dietary fat type and level on broiler breeder performance.

The effects of added dietary fat type and level on broiler breeder performance were evaluated in two trials. In Trial 1, diets included no added fat (NAF) or 3.0% added poultry fat (PF) for individual bird energy intakes of 430 and 467 kcal/d at peak production (PCD), or 1.5% PF or 3.0% corn oil (CO) at 449 PCD. In Trial 2, diets contained NAF, 1.5 or 3.0% added CO or PF, or 3.0% lard (LA) for peak energy intakes of 463 PCD. All diets in Trial 2 were isocaloric and isonitrogenous. Feeding of experimental diets was initiated when breeders were 22 wk old in both trials, and hen BW was measured at various weeks between 22 and 47 wk in Trial 1 and between 27 and 65 wk in Trial 2. Egg production, egg weight (EW), eggshell quality, and hatchability were recorded at various weeks between 24 and 48 wk in Trial 1 and between 27 and 64 wk in Trial 2. Body weights and EW increased progressively, and eggshell quality fluctuated variably with age. Egg production peaked between Weeks 32 and 35, and hatchability was significantly depressed at Week 63. Egg weight and hatchability were not affected by dietary treatment; however, BW increased with energy level in the diet between Weeks 27 and 47. Body weight was also higher in birds fed 1.5 or 3.0% added fat compared with NAF and was higher in birds fed LA compared with CO at the 3.0% level. Egg specific gravity and shell weight per unit of surface area at Week 41 were increased by feeding low or high energy compared with moderate energy, and relative eggshell conductance was increased by using moderate compared with high energy diets and by feeding 1.5% PF compared with 3.0% PF. Egg specific gravity was increased by PF when compared with CO across fat level at Weeks 26 and 47 and by LA when compared with PF across fat level and breeder age. These data suggest that certain dietary energy and fat regimens may affect BW and eggshell quality without associated effects on EW and hatchability at various breeder ages.

Age Factors↗
PubMed1996

Pasteurization of eggs in the shell.

A small percentage of all eggs may be contaminated with Salmonella enteritidis (SE). To eliminate this hazard from the food supply, procedures for pasteurizing eggs in the shell have been developed. At least four research groups are attempting to devise a process to achieve a pasteurized shell egg. Only one of the groups has reported procedures and results. Sound shell eggs were washed to remove surface contaminants. The clean eggs were then inoculated with high levels of SE cells. The inoculated eggs were then heated by one of several means to a yolk temperature of about 55 C and held at that temperature for varying periods of time. The number of surviving cells was determined. It is possible to obtain a 7 log cycle reduction of SE in inoculated eggs without a significant change in functional or visual quality of the eggs.

Animals↗
PubMed2006

Hormonal priming, induction of ovulation and in-vitro fertilization of the endangered Wyoming toad (Bufo baxteri).

The endangered Wyoming toad (Bufo baxteri) is the subject of an extensive captive breeding and reintroduction program. Wyoming toads in captivity rarely ovulate spontaneously and hormonal induction is used to ovulate females or to stimulate spermiation in males. With hormonal induction, ovulation is unreliable and egg numbers are low. The sequential administration of anovulatory doses of hormones (priming) has increased egg numbers and quality in both anurans and fish. Consequently, we tested the efficacy of a combination of human Chorionic Gonadotrophin (hCG) and Luteinizing Hormone Releasing Hormone analogue (LHRHa) administered as one dose, or two or three sequential doses to Bufo baxteri on egg numbers, fertilization and early embryo development. Spawning toads deposited eggs into Simplified Amphibian Ringers (SAR) solution to enable controlled in-vitro fertilization (IVF) with sperm from hormonally induced male toads. Unprimed females receiving a single mixed normally ovulatory dose of 500 IU hCG plus 4 micrograms of LHRHa produced no eggs. Whereas females primed with this dose and an anovulatory dose (100 IU hCG and 0.8 micrograms of LHRHa) of the same hormones, or primed only with an anovulatory dose, spawned after then receiving an ovulatory dose. Higher total egg numbers were produced with two primings than with one priming. Moreover, two primings produced significantly more eggs from each individual female than one priming. The cleavage rate of eggs was not found to differ between one or two primings. Nevertheless, embryo development with eggs from two primings gave a significantly greater percentage neurulation and swim-up than those from one priming. Of the male toads receiving a single dose of 300 IU hCG, 80% produced spermic urine with the greatest sperm concentration 7 hours post-administration (PA). However, peak sperm motility (95%) was achieved at 5 hours PA and remained relatively constant until declining 20 hours PA. In conclusion, Bufo baxteri egg numbers and quality benefited from sequential priming with LHRHa and hCG whereas spermic urine for IVF was produced from males with a single dose of hCG. The power of assisted reproduction technology in the conservation of endangered amphibians is shown by the release of nearly 2000 tadpoles produced by IVF during this study.

Animal Husbandry↗
PubMed2001

Incorporation of dietary linoleic and conjugated linoleic acids and related effects on eggs of laying hens.

In the present study, laying hens received 29 g per kg diet of a preparation containing either 70% linoleic acid (LA) or approximately the same amount of conjugated linoleic acid (CLA) in the control and experimental treatments, respectively. The CLA preparation consisted predominantly of cis-9,trans-11 and trans-10,cis-12 fatty acid isomers as free fatty acids in a ratio of 1:1. The diets were fed for 8 wk to determine the effect of dietary CLA on quality characteristics of eggs. In addition, the fatty acid composition of liver and heart was analyzed. Performance parameters (egg weight, feed efficiency) were not significantly affected by feeding the diets supplemented with CLA. The overall amount of CLA that was incorporated into yolk was 7.95 g CLA/100 g total fatty acids, or approximately 400 mg CLA/egg. The transfer efficiency of the cis-9,trans-11 isomer was higher than that of the trans-10,cis-12 isomer; however, the transfer rate of CLA isomers into yolk and tissues was significantly lower than that of linoleic acid. Dietary CLA increased the concentration of saturated fatty acids in yolk and tissues at the expense of monounsaturated fatty acids. The proportions of myristic, palmitic, and stearic acids in yolk lipids were also changed by dietary CLA. Additionally, long-chain polyunsaturated fatty acids (arachidonic acid and docosahexaenoic acid) were decreased without changing the balance of the n-6/n-3 ratio in egg yolk. The inclusion of CLA in layer diets altered the shape of the yolk and various egg parameters (albumen height, foam index, and yolk index). The results of this study indicate that CLA induces various changes in lipid and fatty acid metabolism of laying hens and affects quality characteristics of eggs.

Animal Feed↗
PubMed2002

Re-evaluation of calcium and phosphorus requirements in aged laying hens.

1. A series of 5 trials was conducted with 401- to 650-d-old Lohmann, Yafa (local breed with brown eggshells) and Yarkon (local breed with white eggshells) hens fed for 56 to 84 d with diets containing 25 to 50 g/kg calcium (Ca) and 4.5 to 7.6 g/kg phosphorus (P). 2. Increasing dietary Ca from 24-25 to 36-40 g/kg improved egg production, shell weight (SW) and shell thickness (ST), and decreased mortality. 3. Increasing dietary Ca to 48 to 50 g/kg did not affect egg production but increased SW and/or ST. In one out of the 4 trials, this effect was not significant, most likely because of the high shell quality of the eggs from the Yafa hens used for this trial. 4. Dietary P content of 4.5 g/kg (1.0 g/kg added inorganic P) appears to be sufficient for maintaining egg production and shell quality in aged laying hen given 36 to 40 g/kg Ca. 5. Increasing dietary Ca above 40 g/kg may require a higher dietary P content.

Aging↗
PubMed2001

Long-term effects of feeding flaxseed-based diets. 1. Egg production parameters, components, and eggshell quality in two strains of laying hens.

We used a split-plot design of five diets: control (corn-soy) with 3.8% Ca, 10% flaxseed with 3.8% Ca, 10% flaxseed with 4.5% Ca, 10% flaxseed with 3.8% Ca and 22,000 IU vitamin D3/kg, and 10% flaxseed with 4.5% Ca and 22,000 IU vitamin D3/kg, and two strains of birds, DeKalb Delta (DD) and Hy-Line W-36 (HL), to evaluate long-term effects of flaxseed supplementation on egg production parameters. Each of the five treatments was randomly assigned and replicated six times with five hens per replicate pen from 21 to 57 wk of age. Phase I was from 21 to 39 wk, Phase II was from 40 to 48 wk, and Phase III was from 49 to 57 wk. Feed consumption was significantly (P < 0.04) greater for the hens fed 10% flaxseed diets (100.9 g) when compared to the corn-soy controls (99.3 g). Overall average egg production (P < 0.05) was 87.8, 87.1, 86.0, 87.1, 84.8, for diets 1, 2, 3, 4, and 5, respectively. Average hen weights during the study were significantly lower for the flaxseed-fed hens (1.559 kg) compared to the controls (1.616 kg). Egg weight was significantly affected by diet during Phase III with heavier eggs from flaxseed fed hens (62.6 g) compared to controls (61.44 g), but overall egg weight was not significantly affected. Average egg mass was not significantly affected by dietary treatments, but DD hens had a decrease in egg mass with Ca supplementation (Diet 2 vs. Diet 3), whereas HL egg mass increased with Ca supplementation. Percentage albumen had a significant strain effect and strain by diet interactions. Overall, significantly less albumen (P < 0.001) was produced by HL (59.4%) compared to DD (61.3%). Supplemental Ca increased albumen percentage in DD (interaction effect P < 0.03) and decreased albumen percentage in the HL strain. Flaxseed supplementation significantly increased albumen percentage (P < 0.02) when compared to the corn-soy control, 60.5 and 59.9%, respectively. An interaction effect (P < 0.01) was noted for percentage wet yolk, in which increasing Ca decreased wet yolk percentage in DD but increased yolk percentage in HL. Wet yolk percentage was also significantly (P < 0.001) less in DD (25.0%) when compared to HL (26.9%). Addition of flaxseed decreased yolk percent when compared to controls (P < 0.03) during Phase II. Ca supplementation significantly (P < 0.03) increased yolk solids in both strains. Grams of yolk solids per egg were affected by flaxseed supplementation (P < 0.06). Flaxseed eggs contained 7.18 g per egg yolk solids compared to 7.3 g in corn-soy control group. Wet shell percentage was significantly lower in the flaxseed diets (12.4%) when compared to the controls (12.6%). Addition of flaxseed to the diet of laying hens did not have any adverse effects on egg production parameters, but flaxseed supplementation can significantly alter weight of yolk solids and yolk and albumen percentages.

Age Factors↗
PubMed2005

Blue and green egg-color intensity is associated with parental effort and mating system in passerines: support for the sexual selection hypothesis.

Among several adaptive explanations proposed to account for variation in avian egg color, that related to sexual selection is of particular interest because of its possible generality. Briefly, it proposes that because biliverdin (the pigment responsible for blue-green eggshell coloration) is an antioxidant, deposition in the eggshell by laying females may signal the capacity of females to control free radicals, despite the handicap of removing this antioxidant from their body. If males adjust parental effort in response to the intensity of the blue coloration of eggs, thereby investing more in the offspring of high-quality mates, blue eggs may represent a postmating sexually selected signal in females. Here, by image and spectrophotometric analyses of the eggs of European passerines, we tested two different predictions of the hypothesis. First, variables related to intraspecific variation in parental effort (i.e., the duration of the nestling period controlled for body mass) should be positively related to the intensity of blue-green color of the eggshell across species. Second, there should be a positive relationship between intensity of blue-green color of eggs and degree of polygyny. These predictions were supported: intensity of blue-green coloration (i.e., chroma) was significantly related to the duration of the nestling period and to degree of polygyny after controlling for possible confounding variables (i.e., body mass, incubation period, and nest type) and similarity due to common descent. Nest type (hole or nonhole) also explained a significant proportion of variation in egg chroma, perhaps reflecting different selection pressures (i.e., light conditions, risk of parasitism) affecting species with the two types of nests.

Animals↗
PubMed2006

Fitness consequences of variable maternal provisioning in quacking frogs (Crinia georgiana).

Variable maternal provisioning may evolve when there is variation in the quality of offspring environments. The frog Crinia georgiana has high variability in egg size both within and between clutches, independent of female phenotype. It breeds in ponds with high spatial and temporal variation in habitat quality. Egg size strongly affected offspring fitness in good and poor quality offspring environments, whether the egg size difference was from between or within clutches. Since there is a trade-off in egg size and number, these fitness consequences translate to strong effects on maternal fitness. In the variable and unpredictable offspring environment of C. georgiana, the maintenance of variable maternal provisioning both within and between clutches is likely to be an evolved response to the offspring environment.

Analysis of Variance↗
PubMed1998

Influence of dietary osteolathyrogens on the eggshell quality of laying hens.

1. Laying hens were fed osteolathyrogens, either semicarbazide hydrochloride at 0.3 or 0.4 g/kg or beta-aminopropionitrile fumarate at 0.5 or 0.6 g/kg diet to examine their effects on eggshell quality. 2. Shell quality characteristics considered for evaluation were shell surface area, shell thickness, shell weight, percentage shell, shape index and the specific gravity of eggs. Measurement of shell quality traits revealed that the hens fed osteolathyrogens laid eggs with significantly lower specific gravities and proportion of shell by weight. These differences were not explained by differences in shell thickness or weight or the shape index of eggs. 3. It was concluded that osteolathyrogens cause hens to lay eggs with poor shell quality and such eggs are weak and fragile.

Aminopropionitrile↗
PubMed1985

Preovulatory concentrations of progesterone and estradiol in plasma and their relationships with eggshell quality in the laying hen.

Laying hens were divided into high and low shell quality groups on the basis of egg specific gravity during the 5th, 7th, and 9th months of egg production. Concentrations of progesterone and estradiol-17 beta in the plasma were determined by radioimmunoassay in blood samples taken by cardiac puncture from hens at either 18, 21, or 24 hr postoviposition. Egg production and egg weight were not significantly different between shell quality groups; however, hens in the low shell quality group were heavier (P less than .05), had longer clutches (P less than .05), and lower egg specific gravity (P less than .0001) than hens in the high shell quality group. Egg production and clutch size declined (P less than .01) in both groups with increased age. Plasma estradiol and progesterone concentrations were not different between shell quality groups or among periods of production, though progesterone and estradiol concentrations were greater (P less than .005) at 21 hr postoviposition than at 18 or 24 hr. The correlation coefficient between plasma concentrations of estradiol and progesterone was significant. There was no significant association between the plasma concentrations of these hormones and egg shell quality. These data suggest that concentrations of estradiol and progesterone in plasma, during the 6 hr before ovulation, are not highly related to shell quality in the laying hen.

Animals↗
PubMed1977

The effect of feeding magnesium-enriched diets on the quality of the albumen of stored eggs.

1. Pullets were given from 1-d-old diets containing 1-6, 4-1, 8-1 and 12-0 g Mg/kg. Only small effects of these diets on live weight, food consumption, egg number, egg weights or egg-shell thickness were observed except at the highest level (12-0 Mg/kg) which caused diarrhoea and an appreciable lowering of the live weight of growing pullets. A further group was given from point-of-lay a diet containing 9-3 g Mg/kg. 2. Eggs laid on 3 consecutive days from each of eighteen hens were collected at intervals of 3 weeks until the birds were 68-5 weeks old. Eggs laid on the 3rd day were used to determine the initial proportion of thick egg-white present and also the concentration of Mg, Ca, Na and K in the thick egg-white. Eggs laid on the 1st and 2nd days were stored at 20 degrees for 20 d to establish the proportion of thick egg-white remaining after storage. 3. With the unsupplemented diet the proportion of residual thick egg-white after storage of eggs for 20 d at 20 degrees was 306, 161 and 305 mg/g total egg-white when the hens were 26-5, 53-5 and 68-5 weeks of age respectively. When the diet containing 9-3 g Mg/kg was given, the proportion of thick egg-white after storage remained approximately 400 mg/g throughout the period of the trial. 4. The mean Mg concentration in the thick egg-white of eggs laid by hens given unsupplemented diets was 5-77 mM. The addition of extra Mg to the diet increased the content of Mg in the thick egg-white, for example when the diet contained 9-3 g Mg/kg the mean concentration rose to 7-69 mM.

Animal Feed↗
PubMed2004

Magnesium in animal nutrition.

Magnesium (Mg) supplementation remarkably improves the digestibility of feed. In cows and sows, it has improved the reproduction and shortened the service period. In broilers it increased weight gain, and it has increased egg production of laying hens. In addition, increasing Mg intake benefits the quality of breeding eggs and improves hatching yield. However, increasing Mg intake has not altered visceral composition of embryos, although brain and liver might have the capacity to store Mg at intake above the requirement.

Animal Feed↗
PubMed2002

The effect of twenty-eight-hour ahemeral day lengths on carcass and reproductive characteristics of broiler breeder hens late in lay.

The effect of increasing the day length from 24 to 28 h on the reproductive and carcass characteristics of old broiler breeder hens was examined. A total of 128 birds aged 47 wk of age from three different strains; Classic, Experimental (EXP), and Feather Sexable Yield (FSY) were used. Selection was based on target BW and egg production rates; birds were housed in light-tight environment chamber facilities. Birds were feed restricted, and feed was allocated according to actual weekly BW relative to target BW. At 55 wk of age 125 broiler breeders were killed and dissected, and carcass and reproductive traits were examined. Overall, ahemeral day length negatively affected carcass and reproductive parameters. No significant differences were found for BW, yolk, albumen and shell weights, normal and atretic ovarian follicles, and breast, fat pad, and liver weights. Significantly lower production rates, higher amounts of defective eggs, lower oviduct and ovary weights, lower F1 follicle weight, poorer eggshell quality, and higher egg weights were found. Subsequently, broiler breeder hens increased egg weight at the expense of egg production when subjected to an ahemeral day length. It is not recommended that day length be increased this late in production because it results in reduced egg productivity.

Animal Husbandry↗
PubMed2004

Egg-laying capacity is limited by carotenoid pigment availability in wild gulls Larus fuscus.

In birds, experimentally increased egg production can reduce maternal condition, parenting ability and survival, and the quality of the eggs themselves. Such costs probably reflect resource limitation, but the identity of the resource(s) in question remains unclear. Carotenoids are antioxidants and immunomodulants that birds can only obtain in their diet. Trade-offs in the allocation of limiting carotenoids between somatic maintenance and egg production could therefore be an important factor underlying reproductive costs. We show that in wild lesser black-backed gulls, Larus fuscus, dietary carotenoid availability (i) constrained the capacity to re-lay following clutch removal; and (ii) affected the relationship between yolk mass and egg mass. However, whether carotenoids are limiting for egg production directly, by stimulating the synthesis or antioxidant protection of yolk precursors, or indirectly via effects on maternal health, requires further study.

Analysis of Variance↗