不同周龄母鸡鸡蛋及不同蛋壳质地鸡蛋的蛋品质比较

本文比较了同一品种不同周龄(26、40周龄和64周龄)母鸡所产蛋的蛋壳品质和蛋品质,包括蛋重、蛋壳相对重、蛋形指数、蛋壳强度、蛋壳厚度、蛋黄颜色、蛋黄指数、蛋黄比率、哈氏单位、蛋清pH值。之后,还比较了该鸡种不同蛋壳质地鸡蛋(正常蛋和砂壳蛋)之间上述指标的差异。结果表明:在不同周龄母鸡所产蛋之间,蛋重、蛋黄指数、蛋黄比率、哈氏单位等均存在显著差异(p<0.05),而蛋壳厚度之间差异不显著(p>0.05)。此外,蛋重、蛋形指数、蛋黄颜色、蛋黄比率随着母鸡周龄的增加呈上升趋势,而蛋壳强度、蛋壳相对重、哈氏单位、蛋黄指数、蛋清pH值呈下降趋势。最后,蛋壳质地不同的鸡蛋(正常蛋与砂壳蛋)之间,蛋重、蛋壳相对重、蛋壳强度、蛋清pH值之间存在极显著差异(p<0.01),而其他参数之间差异不显著(p>0.05)。     

Measuring the eggshell strength of 6 different genetic strains of laying hens: techniques and comparisons

1. Eggshell quality was compared in 6 different strains of laying hens. Three strains were commercial; the three others were experimental. 2. Four different variables describing the strength of eggshells were investigated. Three of them were the classical ones eggshell thickness, shell stiffness measured during quasi-static compression and breaking force. Dynamic stiffness, introduced by Coucke (Ph.D. Thesis, KU Leuven, 1998), was the 4th. The fact that this measurement is dynamic could be helpful in genetic selection for eggshell breakage, because forces applied to the egg in practice are dynamic, rather than static. 3. Hisex White hens produce eggs with the strongest eggshell, in terms of all 4 eggshell variables. However, their shell quality in terms of breaking force did not remain constant over the laying period, unlike 4 other strains. 4. All strains showed a decline in quasi-static stiffness over time. 5. The eggshell thickness of three strains showed a decline over time. 6. Dynamic stiffness remained constant or improved in all strain. 7. All variables describing the mechanical eggshell strength gave different information.     

孕酮对鸡蛋壳品质的影响

本试验旨在通过腿肌注射孕酮来研究孕酮对蛋壳品质的影响。选取72只40周龄的海兰褐蛋鸡,随机分为6组,每组12只蛋鸡,单笼饲养。对照组注射花生油;处理1在排卵后5 h注射1.00 mg/kg体重(BW)的孕酮;处理2和处理3分别在排卵后5 h和2 h注射0.25 mg/kg BW的孕酮;处理4和处理5分别在排卵后2 h和1 h注射0.15 mg/kg BW的孕酮。处理后第2天上午收集各组所产鸡蛋,测定蛋壳强度和厚度。结果表明:处理1所产蛋均为破壳蛋,处理2含部分破壳蛋和部分蛋壳完好的鸡蛋,处理3、处理4和处理5没有破壳蛋;与对照组相比,处理1和处理2的蛋壳厚度降低(P<0.05),处理4蛋壳强度和厚度增加(P<0.05),处理3和处理5的蛋壳强度和厚度无显著差异;与对照组比,处理1和处理4的蛋壳超微结构差异显著。结果显示,孕酮可以影响蛋壳强度和厚度,改变蛋壳超微结构,其影响程度与剂量和注射时间有关。     

Effect of intensity of eggshell pigment and illuminated incubation on hatchability of brown eggs

The effects of intensity of brown eggshell pigment (light (LBP), medium (MBP) and dark (DBP)) and light intensity during incubation (low and high, 900 to 1380 and 1430 to 2080 lux, respectively) on eggshell characteristics, embryonic growth, hatchability traits, chick hatching weight and hatching time were investigated using eggs from a meat-type breeder (Hybro) flock at 32, 36 and 41 weeks of age in three trials. With eggs of similar weights the intensity of brown pigment was not associated with eggshell weight and thickness, and did not influence embryo weight and egg weight loss during incubation. The shade of brown pigment of eggs laid by young hens influenced the percentage hatchability (HP) of eggs incubated under light. Illuminated incubation improved HP of LBP eggs (compared with MBP and DBP eggs) from 32- and 36-week-old hens, but had no significant effect on HP of eggs from 41-week-old hens. Light intensity during incubation did not influence egg weight loss. High intensity of light during incubation reduced HP and increased early death percentage (EDP) in the LBP and MBP groups, and did not influence HP and EDP in the DBP group. Brown eggshell pigment and intensity of light during incubation did not influence hatching time. It is concluded that the shade of brown pigment, intensity of light during incubation and age of the breeder hens influenced the hatchability performance of embryos from brown eggs. Light during incubation improved the hatchability of embryos in light brown eggs laid by young hens and the shade of brown pigment of eggs laid by older hens did not influence hatchability under illuminated incubation. High intensity of light during incubation reduced hatchability of light and medium brown eggs, but not the dark brown eggs.     

Ascorbic acid biosynthesis in hens producing strong and weak eggshells

1. An experiment was conducted with two strains of layers to ascertain whether the reduction in eggshell strength occurring at the end of the production cycle is the result of reduced ascorbic acid biosynthesis. 2. Hens producing strong and weak eggshells were identified within each strain and egg production, egg weight, per cent shell, shell surface density, plasma, adrenal and hepatic ascorbic acid and renal L-gulonolactone oxidase activity were measured. 3. The strains differed in ascorbic acid synthesis, as measured by L-gulonolactone oxidase activity, and tissue ascorbic acid concentration. 4. Comparison of results from birds producing eggs of similar weight but markedly different in shell strength detected neither a shell strength group x strain interaction nor an effect of shell strength group on plasma and hepatic ascorbic acid and activity of L-gulonolactone oxidase. 5. The results did not support the hypothesis that tissue ascorbate and ascorbic acid biosynthesis are reduced in old hens producing weak eggshells.     

Changes in eggshell mechanical properties, crystallographic texture and in matrix proteins induced by moult in hens

The effect of moult on eggshell mechanical properties, on composition and concentrations of organic matrix components and on eggshell microstructure was investigated. The observed changes were studied to understand the role of organic matrix and eggshell microstructure in eggshell strength. Moult was induced by zinc oxide (20 g zinc/kg diet) in 53 ISA Brown laying hens at 78 weeks of age. No difference was observed for egg or eggshell weights after moult. In contrast, moult improved the shell breaking strength (28.09 vs 33.71 N). After moult, there was a decrease in the average size of calcite crystals composing the eggshell and in their heterogeneity, whereas crystal orientation remained basically the same. After moulting, the total protein concentration in eggshell increased slightly. The comparisons of SDS-PAGE profiles of the organic matrix constituents extracted before and after moulting showed changes in staining intensity of certain bands. After moult, bands associated with main proteins specific to eggshell formation (OC-116 and OC-17) showed higher staining intensity, while the intensity of the egg white proteins (ovotransferrin, ovalbumin and lysozyme) decreased. ELISA confirmed the decrease in ovotransferrin after moult. Its concentration was inversely correlated with breaking strength before moult. These observations suggest that changes in eggshell crystal size could be due to changes in organic matrix composition. These changes may provide a mechanism for the improvement in shell solidity after moulting.     

New approach of testing the effect of heat stress on eggshell quality: mechanical and material properties of eggshell and membrane

1. The effect of high temperature on eggshell quality was investigated by measuring the mechanical and material properties of shell and membranes. 2. Heat exposure resulted in a decrease in zootechnical performance and eggshell thickness, increase in egg breakage, and unchanged egg shape index. 3. The static stiffness (Kstat), dynamic stiffness (Kdyn) and modulus of elasticity of the eggshell were not significantly affected by high temperature. Membrane prolongation increased significantly while membrane attachment strength and breakage strength tended to decrease and increase, respectively. The relationships between these variables were changed by high temperature. 4. Neither Kstat nor Kdyn could give a reasonable explanation for the changed eggshell quality induced by heat stress. The decreased eggshell thickness and changed properties of shell membrane may be responsible, at least partially, for the decreased shell quality of eggs from heat-stressed hens.     

Influence of dietary osteolathyrogenson the eggshell quality of laying hens

1. Laying hens were fed osteolathyrogens, either semicarbazide hydrochloride at 0.3 or 0.4 g/kg or β-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.     

Organic matrix composition and ultrastructure of eggshell: a comparative study.

1. The avian eggshell is a biomineralised composite ceramic consisting of calcium carbonate embedded in an organic matrix. Matrix components are supposed to be involved in the control of mineralisation, crystallographic texture and biomechanical properties of eggshell. 2. The structure and eggshell matrix composition of various domesticated bird species were compared to gain insight into the universality of the eggshell mineralisation process. 3. The SDS-PAGE profiles of soluble eggshell matrix were specific within groups of birds (a: laying hen, breeder hen, quail, pheasant and possibly turkey; b: guinea fowl; c: duck and goose) but some of the protein bands were common to all groups. 4. Analogies between species were confirmed by Western blotting using hen protein antibodies. Ovocleidin-17 (OC-17) and ovalbumin were revealed in all species (except quail for OC-17). Lysozyme was present only in hen eggshell. Another egg white protein: ovotransferrin showed a positive signal in hens, turkey and quail. Osteopontin was observed in laying and breeder hens and quail. 5. Different proteoglycans were localised to discrete regions within the eggshell. Dermatan sulphate was observed within the matrix of the calcified shell of all species except quail which contained chondroitin-6-sulfate. Keratan sulphate was observed in mammillary bodies of breeder and laying hen, quail, pheasant and turkey while chondroitin sulphate was also present in guinea fowl and duck. 6. The general structural organisation of the different avian eggshells was similar but specific differences were observed in the ultrastructure of the mammillary layer. Species of the same taxonomic family could be grouped according to their structural analogies: breeder hen, turkey and pheasant resembled that of the domestic fowl. Guinea fowl was unique. Goose and duck were quite similar with large and confluent mammillary bodies. 7. Some matrix components are therefore common to eggshells of various species but more information is needed to relate differences in matrix composition between taxonomic groups with differences in ultrastructure.     

Vitamin C Overcomes the Detrimental Effect of Vanadium on Brown Eggshell Pigmentation

Phosphorus supplementation from poor quality feed-grade sources may introduce excessive levels of vanadium (V) into the diets of laying hens. Vanadium in the diet of chickens has been shown to be detrimental to egg production, albumen height, BW, and feed consumption. This study showed that dietary V also has a negative effect on the color of brown eggshells from commercial-type layers. Commercial-type brown egg layers were fed a cornsoybean meal basal diet supplemented with 0, 50, or 100 ppm of V as NH₄ VO₃ to determine the effect on shell pigmentation. Hens fed V at both dietary concentrations laid lighter colored eggs (less redness) after only 2 d. Another experimental group of the same type of hens that were fed lower V concentrations (0, 15, or 30 ppm) also had less shell pigmentation. After the detrimental “bleaching” effect on shell color was observed, these diets were supplemented with 1 of the following: no supplement, 100 ppm of vitamin C, 100 IU of vitamin E, or 100 ppm of β-carotene. Only vitamin C restored the eggshell color of eggs from hens fed both levels of V. When these same antioxidants were added as preventive agents to diets supplemented with 15 ppm of V before the effects of V were established, brown layers benefited again from 100 ppm of vitamin C but not from vitamin E or β-carotene.     

Physical and mechanical properties of eggshell as affected by chicken breed and flock age

ABSTRACT

1. A study was conducted to evaluate the relationship among physical and mechanical properties of the eggshell, as affected by breed and hen’s age.

2. Data on eggshell quality (external characteristics and derived measurements) were obtained from 322 laying hens, from three breeds (Fayoumi, Dandarawi and Hy-Line Brown) during the laying cycle, starting from 38 wks of age for four experimental periods (38, 46, 54 and 62 wks).

3. Eggs obtained from the Fayoumi breed exhibited the highest shell thickness and breaking force. There was a linear improvement in eggshell quality attributes associated with hen’s age up to 54 wks, thereafter a deterioration was found for all breeds.

4. Generally, eggs laid by native breeds (Fayoumi and Dandarawi) had better mechanical properties compared to those produced by the commercial strain (Hy-Line Brown). In addition, the interaction between breed and hen’s age was not significant for any physical property or mechanical attribute. There was a highly significant (P ≤ 0.01) positive correlation between the breaking force and either eggshell toughness or shell thickness, and regression analyses suggested that eggshell toughness was the best predictor for breaking force, followed by shell thickness.     

Heritability and genetic correlation of measurements derived from acoustic resonance frequency analysis; a novel method of determining eggshell quality in domestic hens

Cracked eggshells result in economic loss and provide a route for pathogenic organisms to enter the egg. Genetic factors that contribute to shell strength are likely to decrease the risk that an egg will crack when subject to insult. A novel measurement, the dynamic stiffness of the eggshell (Kdyn) was examined to determine if it might be used in the genetic selection of hens with improved eggshell characteristics. The measurement is determined from acoustic resonance frequency analysis. The estimates of heritability for the novel measurement of Kdyn were moderately high and ranged from 0.33 to 0.53 depending on the model used for the estimation. The estimates of genetic correlation of Kdyn with eggshell breaking strength (0.49) and static stiffness (0.57) were positive and relatively large as expected. There was a small negative genetic correlation between Kdyn and egg production from 26 to 50 weeks of age (-0.19) and a moderate one from 58 to 74 weeks of age (-0.36). The moderate heritability and relative independence of Kdyn indicates that this measurement could be used successfully in a breeding programme to improve shell quality and to reduce the incidence of cracks.     

Comparison of hatchability and some egg quality characteristics in spotted and unspotted partridge (Alectoris chukar) eggs

The current research was conducted to determine the comparison of hatchability and some egg quality characteristics in spotted and unspotted partridge (Alectoris chukar) eggs. The research was carried out on 51 male and 102 female chukar partridges (Alectoris chukar) aged 50 wk, which were raised at the Research and Application Farm of the Faculty of Veterinary Medicine of Selcuk University. In total, 244 spotted and 261 unspotted eggs were used in the research. The hatching eggs were stored at 75% RH and 13°C for 14 d. Thirty spotted and 30 unspotted eggs laid on the same day were used for the evaluation of egg quality characteristics. Egg weight, chick weight, egg weight loss during the hatching period, shape index, hatchability, and some egg quality characteristics were evaluated at the end of the research. Spotted eggs exhibited a higher fertility and hatchability, as well as a lower percentage egg weight loss and embryonic mortality when compared with unspotted eggs. No significant differences were observed between spotted and unspotted eggs for egg weight, chick weight, shape index, specific gravity, albumen height, Haugh unit, yolk color green-red chromaticity (a*), albumen pH, and yolk pH. Spotted eggs had higher eggshell color a*, eggshell color blue-yellow chromaticity (b*), and eggshell strength, as well as a lower eggshell color light-dark chromaticity (L*), yolk color L*, and yolk color b* scores when compared with unspotted eggs. It was demonstrated that spots on the eggshells of chukar partridges (Alectoris chukar) improved their hatchability by affecting various quality characteristics of their eggs. It was concluded that spotted eggs are more suitable for hatching.     

The effect of chronic lead intoxication in mature chickens

In a study of chronic lead intoxication in mature chickens, blood lead levels were significantly lower in hens than in roosters receiving the same oral dose of lead. It was then shown that eggshells from lead-treated hens contained 6-12 times the lead concentration of eggshells from control hens. Similarly, the lead content of egg yolks from treated hens was significantly higher than yolks from controls. Lead-treated hens laid significantly more eggs during the period of observation of nearly 3 years because of the increased frequency of laying cycles, which was almost three times that of control hens. A further observation was histologic damage to the mature testes of the rooster.     

不同品种鸡蛋品质的比较研究

随机抽取40周龄尼克粉鸡、仿草鸡、苏禽黄鸡、青壳蛋鸡的蛋各100个,进行蛋品质测定。结果表明不同品种鸡蛋的蛋品质存在着差异,除蛋形指数差异不显著外,4种鸡蛋的蛋壳颜色和蛋黄颜色相互间存在极显著差异(P<0.01);尼克粉鸡蛋、苏禽黄鸡蛋与仿草鸡蛋及青壳蛋鸡蛋的蛋重相互间存在极显著差异;尼克粉鸡蛋、青壳蛋鸡蛋与仿草鸡蛋、苏禽黄鸡蛋的蛋黄比率存在极显著差异;尼克粉鸡蛋与仿草鸡蛋、苏禽黄鸡蛋、青壳蛋鸡蛋的蛋壳厚度存在极显著差异;4种鸡蛋的哈氏单位相互间表现出显著(P<0.05)或极显著的差异;蛋壳强度只在尼克粉鸡与仿草鸡之间有显著差异。     

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.     

Frustrated nesting behaviour: relation to extra-cuticular shell calcium and bone strength in White Leghorn hens

1. The inability of hens to express normal nesting behaviour in battery cages results in frustration, manifesting itself as stereotyped pacing. Frustration can cause hens to retain their eggs beyond the expected time of lay, resulting in an extra-cuticular layer of calcium on eggshells. 2. This study investigated whether frustrated nesting behaviour caused extra-cuticular calcification of eggshells and whether this loss of non-structural calcium to eggshells may have subsequently contributed to weak bones in spent hens. 3. One hundred and twenty hens were assigned to one of three treatments: NB (hens given nest boxes in their cages), NN (no nest box) and R (access to nest box periodically restricted). 4. NB hens spent the least amount of time pacing in the hour before oviposition. NN and R hens spent similar amounts of time pacing. 5. Contrary to expectation, eggshells from hens under different treatments yielded the same amount of extra-cuticular calcium. Similarly tibia strength did not significantly differ among treatments.     

Effects of avian infectious bronchitis virus (Arkansas strain) on vaccinated laying chickens

Twenty-four-week-old white leghorn layers were inoculated subcutaneously with a killed Newcastle-infectious bronchitis (Massachusetts type) virus (MIBV) vaccine. The birds were challenged 194 days later intraocularly with Arkansas strain of infectious bronchitis virus (AIBV). The challenged hens laid significantly (P less than 0.005) fewer eggs than the unchallenged layers, and the eggs laid by the challenged groups weighed significantly less (P less than 0.001) than those laid by the unchallenged groups. Further, the internal quality (Haugh units) and shell quality of eggs laid by the challenged hens were significantly (P less than 0.005) inferior to the quality of eggs from unchallenged hens, and the challenged hens laid more soft-shelled, misshapen, and small-sized eggs than the unchallenged hens. The Arkansas serum hemagglutination-inhibition (AIBV-HI) titers of challenged birds increased continuously through 29 days post-challenge. The MIBV hemagglutination-inhibition (MIBV-HI) titers of killed-MIBV-vaccinated birds decreased during the same period. The study indicates that killed MIBV vaccine offered no protection to birds exposed to AIBV. The same vaccine was quite effective against a homologous (MIBV) virus challenge.     

Structural and physical changes in the hen's eggshell in response to the inclusion of dietary organic minerals

1. An experiment was designed to determine whether the inclusion of sodium selenite, Sel-Plex or Sel-plex?+?Bioplex in the diet exerted any influence on structural and functional properties of the eggshell at 22, 38, 58 and 72 weeks age.

2. Significant age effects were demonstrated for egg weight, dynamic stiffness and total shell thickness.

3. The eggshells from birds fed on the Sel-Plex?+?Bioplex treatment were statistically stronger than those produced by the birds on sodium selenite.

4. From mid-lay onwards the shells laid by birds fed on the Sel-Plex?+?Bioplex treatment displayed, at ultrastructural level, the crystal modification termed ‘confluence’ together with early fusion of the palisade columns which comprised the bulk of the shell.

5. At all periods of lay the shells of birds fed on sodium selenite, Sel-Plex and the control diet demonstrated the presence of a variety of crystalline aggregates localised between the forming palisade columns.     

The relationship between the concentration of metals and the rate of liquefaction of thick egg white

The thick white fraction of eggs obtained from mature hens contains less magnesium and liquefies more rapidly than the corresponding thick white gels obtained from eggs laid by young hens.