Environmental effects on steroid hormone concentrations in laying hens’ eggs

Abstract

The hormone content of a birds’ egg may reflect the environmental conditions of the bird. In this study we measured hormone concentrations of eggs from hens living under different housing conditions. Eggs from 16 floor-housed and 16 singly caged hens were analysed for androstenedione and estradiol. The concentrations of these hormones were highest in the yolk of eggs from floor-housed hens (P≤0.05). The concentration of estradiol in the albumen of eggs was highest for caged birds (P≤0.0001). In caged hens, the concentrations of both hormones varied significantly over days in the egg yolk, but not in the albumen. As the concentration of androstenedione and estradiol in the yolk of chicken eggs is environmentally dependent, these hormones may provide a mechanism by which the hen signals the state of the environment to her progeny.     

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)。     

鸡蛋暗斑对蛋品质及抗氧化能力的影响

[目的]研究鸡蛋暗斑对蛋品质及其抗氧化能力的影响。[方法]从饲喂同种日粮、饲养环境相同、同日龄褐壳蛋鸡同一批次所产的褐壳蛋中,用灯光照射法挑选出24枚典型正常蛋、24枚典型暗斑蛋进行试验,并分别对正常蛋和暗斑蛋进行蛋品质、蛋黄抗氧化指标的测定及比较。[结果]蛋品质比较:暗斑蛋与正常蛋相比,其蛋形指数、蛋壳强度、蛋重、哈氏单位、蛋白高度、鸡蛋等级、蛋黄颜色、蛋黄重、蛋壳重、蛋清重、蛋壳厚度、蛋黄比重、蛋壳比重、蛋清比重均差异不显著(P>0.05);暗斑蛋蛋壳颜色极显著深于正常蛋(P<0.01)。抗氧化指标比较:暗斑蛋蛋黄的总抗氧化能力(T-AOC)显著低于正常蛋蛋黄的总抗氧化能力(P<0.05),暗斑蛋蛋黄的丙二醛(MDA)含量与正常蛋蛋黄的丙二醛含量相比差异不显著(P>0.05)。[结论]与正常蛋相比,暗斑蛋的蛋壳颜色较深,总抗氧化能力较差。     

Genetic Relations between Reproduction,Chick Weight and Maternal Egg Composition in a White Leghorn Line

Selection is a viable way to increase egg dry matter, an important trait for the egg processing industry, but simultaneously a change in the embryonic environment takes place. The main purpose of this study was to estimate genetic parameters for the percentage of fertile eggs of eggs set (FERT), percentage of eggs hatched of fertile eggs (HATCH), percentage of live chicks 2 weeks post-hatch of hatched eggs (SURV/h) and of fertile eggs (SURV), and their genetic correlations with egg weight, albumen weight, yolk weight, yolk proportion, albumen dry matter and mean chick weight in a White Leghorn selection line. Direct and maternal heritabilities were low for FERT, HATCH and SURV, and non-existent for SURV/h. All direct-direct genetic correlations between reproduction traits and egg composition traits were not significant. Maternal-direct genetic correlations between HATCH and egg weight, albumen weight, yolk weight, yolk proportion and albumen dry matter were - 0.22, - 0.30, 0.28, 0.52 and 0.26, respectively. Similar correlations were found between SURV and egg composition traits. No significant genetic relationship was found between chick weight and post-hatch survival. In conclusion, within the range of values for egg composition in this study, selection for an increased egg dry matter should not impair reproduction.     

Heritability, genetic and phenotypic correlations of egg quality traits in Iranian native fowl

1. The objective was to estimate heritability, genetic and phenotypic correlations for egg quality traits of Iranian native fowl at the Yazd Breeding Centre. 2. External and internal egg quality traits were measured on 1200 eggs from 794 hens of the 6th generation. A multivariate animal model with restricted maximum likelihood procedure was applied to estimate heritability, genetic and phenotypic correlations for egg quality traits using ASREML. 3. Heritability estimates for external egg quality traits ranged from 0·18 to 0·57 and for internal egg quality traits from 0·24 to 0·60. 4. For external egg quality traits, genetic correlation between egg weight and eggshell thickness (EST) was positive (0·36) and EST showed high genetic correlations with eggshell weight (0·84) and eggshell strength (0·55). This implies that heavier eggs tend to have thicker and stronger shells. 5. For internal egg quality traits, albumen height showed high positive genetic correlations with albumen weight (0·52), albumen index (0·98), yolk height (0·72) and yolk index (0·57). 6. Our results show that it is feasible to improve egg quality in Iranian fowl through selection for albumen height.     

产蛋鸡饲粮锌和钙水平对蛋的品质和蛋中锌含量的影响

试验研究了在玉米一豆饼型基础饲粮(含锌30Ppm)中添加不同水平锌和钙对鸡蛋品质和蛋中锌含量的影响。结果表明,饲粮未加锌时后期(70～71周龄)蛋壳比,蚕黄,蛋白和蛋壳风干物含量,蛋的比重和蛋壳厚度显著降低;饲粮高钙使中期(45周龄)和后期蛋壳比,各期蛋的比重和蛋壳厚度显著提高。蛋黄中锌含量随着饲粮锌水平的提高而显著提高;蛋白中锌含量在前期(25周龄)同蛋黄一样,但在中期和后期未加锌组鸡蛋白中锌含量显著高于加锌对照组;蛋壳中锌含量在前期不受饲粮锌水平显著影响,在中期和后期饲粮高锌使之显著提高。饲粮高钙对蛋各组分中锌含量没有显著影响。     

笼养与平养蛋鸭蛋品质测定与相关性分析

试验旨在比较笼养和平养方式对不同品种蛋鸭蛋品质的影响,以期为评价不同饲养方式下的鸭蛋品质提供参考依据。随机选取40周龄笼养和平养的金定鸭（青壳蛋）和山麻鸭（白壳蛋）鸭蛋各30枚于产后24 h内进行蛋品质测定。结果表明,同一品种笼养蛋鸭蛋重极显著大于平养蛋鸭蛋重（P<0.01）,蛋重与蛋壳重、蛋白重和蛋黄重之间均存在极显著正相关（P<0.01）,但不同类型鸭蛋的蛋黄重之间差异不显著（P>0.05）。青壳蛋的蛋壳强度显著高于白壳蛋（P<0.05）,笼养青壳蛋的蛋壳强度亦高于平养青壳蛋（P<0.05）。蛋的比重与蛋壳厚度呈极显著正相关（0.503,P<0.01）,与蛋壳强度的相关系数亦达到0.536（P<0.01）。4种类型鸭蛋的哈氏单位均达到72以上。虽然蛋白重与蛋黄重之间呈极显著正相关（P<0.01）,但蛋白重与蛋黄比率之间却呈极显著的负相关（P<0.01）。蛋的比重与蛋黄重和蛋黄比率之间亦存在显著负相关（P<0.05）。以上结果表明,就蛋品质而言,蛋鸭养殖以采用笼养模式、选择青壳蛋鸭品种为宜。     

One-generation divergent selection on large and small yolk proportions in a White Leghorn line

1. A striking change in egg consumption from shell eggs toward egg products is taking place. Consequently, internal egg quality traits must be seen in a different light, as they may affect the profitability of the egg processing industry. In order to study the possibility of using breeding as a means to alter yolk production, a one-generation divergent selection experiment was set up. The trait was yolk proportion. The effect of hen's age on egg composition was also studied. Genetic parameters for yolk proportion, yolk weight, egg weight and albumen weight were estimated, using a multiple trait animal model, and restricted maximum likelihood. 2. Selection response was obtained for yolk proportion and correlated selection responses for yolk weight and albumen weight. In the 'high line' a decrease in egg weight and an increase in yolk weight was established, whereas in the 'low line', egg weight remained more or less the same and yolk weight decreased slightly 3. Yolk proportion, yolk weight, egg weight and albumen weight all increased with increasing age of the hen in both selection lines. The difference between selection lines in yolk proportion, yolk weight and albumen weight persisted throughout the laying period. 4. Estimated heritabilities for yolk proportion, yolk weight, egg weight and albumen weight were 0.38, 0.22, 0.34 and 0.41 respectively. The genetic correlation between yolk proportion and yolk weight was 0.52, whereas the genetic correlations with egg weight and albumen weight were -0.51 and -0.74 respectively. 5. We conclude that selection can be used to alter yolk production. Selection can be at an early age with a sustained effect throughout the laying period.     

Selection for antibody response against sheep red blood cells and layer age affect egg quality

1. After 22 generations of divergent selection for antibody response against sheep red blood cells (SRBC), hatchability differed between the selected lines. Whether there is a relationship between hatchability and egg traits in these lines is not clear. 2. The aim of the present study was to investigate whether eggs of selected lines differed in shell and albumen characteristics. 3. Fresh eggs were collected at layer ages of 25, 29, 33, 37, 41, 45, 49, 55 and 59 weeks. In total 776 eggs from three lines (high antibody response (H), control (C) and low antibody response (L) against SRBC) were examined. 4. Albumen height decreased with layer age, but this decrease differed between lines. 5. Eggs of the C line were heaviest, followed by the L line and finally the H line (59.44 vs 55.50 vs 54.15 g, respectively). Eggshell thickness, eggshell percentage, albumen height and albumen pH were lowest in the L line, and highest in the H line, whereas the C line was intermediate. 6. From this study, we concluded that selection on antibody response to SRBC affected egg characteristics (external and internal). This may have consequences for hatchability and furthermore for chick quality. When chick quality partly underlies the immune status of an animal, differences in immune responses among selected lines may be due to differences in egg characteristics. This implies inadvertent selection for chick health at an early stage of life. Whether this is the case needs to be investigated.     

缠丝鸭蛋蛋品质及营养成分测定

为研究缠丝鸭蛋和普通鸭蛋在蛋品质及营养成分之间的差异,本试验随机选取300日龄左右鸭产的缠丝鸭蛋和普通鸭蛋各50枚,分别测定其蛋重、蛋壳厚度、蛋壳强度、蛋壳颜色、蛋白高度、蛋形指数、蛋黄色泽和哈氏单位等蛋品质性状及粗蛋白质、粗脂肪、钙、磷、锌和铁等营养成分含量。结果表明,与普通鸭蛋相比,缠丝鸭蛋的蛋重、蛋壳厚度、蛋壳颜色、蛋壳强度和蛋形指数差异均不显著(P>0.05),而蛋白高度、蛋黄色泽和哈氏单位极显著高于普通鸭蛋(P<0.01);蛋白质、钙、锌、铁含量较高,脂肪、磷含量较低。提示,缠丝鸭蛋蛋品质优于普通鸭蛋,营养物质含量比普通鸭蛋更丰富。     

Upgrade of egg quality through different heat-combating systems during high environmental temperature

The aim of the study was to find out the effect of various heat-combating systems (HCS) on the egg quality characteristics of commercial laying hens during high environmental temperature of the year. Three hundred pullets were wing banded and randomly divided into 15 experimental units comprising of 20 pullets each. These units were randomly allotted to five treatment groups, replicated thrice according to four heat-combating systems (desert cooling, water sprinkling, time limit feeding, ascorbic acid supplementation), and the control was maintained under the same housing system. The mean values of egg weight, eggshell thickness, Haugh unit, thick albumen height, yolk height, and yolk diameter were calculated. The layers kept under the influence of desert cooling produced eggs with more weight and thicker shells than those under other systems. Results of the present study did not show any difference in the shell thickness between water sprinkling and ascorbic acid supplementation as compared to the control group. Haugh unit and yolk index values obtained from the layers kept under various HCS did not significantly differ from those of the control group. All HCS significantly reduced the occurrence of blood spots in the eggs as compared to the control. All the treatments in general markedly reduced the incidence of meat spots in the eggs especially with the supplementation of ascorbic acid being the most effective. Among all of the treatments, the desert cooling system proved to be the best for producing better-quality eggs during hot periods of the year with less humidity.     

Morphology and chemical composition of turkey eggs

The objective of this study was to evaluate selected morphological characteristics and the chemical composition of turkey eggs of different weight classes. The percentage of eggs weighing ≥100 g increased to 46.66% in wk 23. Eggs weighing 95 and 110 g had lower yolk content (3.05 and 4.86%) and higher albumen content (by 3.16 and 5.21%) compared with eggs weighing 80 g. The total protein content of the albumen increased (from 9.93 to 10.71%) and the water content of the albumen decreased (from 88.30 to 87.59%) with an increase in egg weight. Albumen weight per gram of yolk increased from 1.87 to between 2.18 and 2.42 g in larger eggs. The energy density of the egg decreased from 5.68 to 4.90 kJ/g with an increase in egg weight, and the energy density of the yolk remained at a similar level in all egg weight classes. The other analyzed yolk and shell parameters were not affected by egg weight. The highest energy and total protein content of the yolk was observed in wk 14 of the laying season. No correlations were found between the progress of the laying cycle and eggshell percentage and the water content of the yolk. The values of the remaining egg parameters varied over the laying season.     

Determination and Correlation Analysis on the Egg Quality of Egg-laying Ducks Reared in Cages and on Floor

The purpose of this test was to evaluate the egg quality from two breeds of ducks reared in cages and on floor.30 eggs were chosen from each type of eggs,which were from Jinding (green shell) and Shan Partridge ducks (white shell)at 40 weeks-old reared in cages and on floor for egg quality evaluation.The results showed that the egg weight of caged duck was extremely significantly larger than the floor duck (P<0.01) in the same breed,there were very significant positive correlations between the egg weight and eggshell weight,egg-white weight and egg yolk weight (P<0.01),but no significant difference among the egg yolk weights of different types of ducks (P>0.05).The shell strength of green egg was obviously higher than that of white shell eggs (P<0.05),and the shell strength of green egg from caged ducks was higher than that of the green egg ducks on floor.The correlation coefficients of the egg specific gravity and eggshell thickness,the specific gravity and eggshell strength were 0.503 (P<0.01) and 0.536 (P<0.01) respectively.Haugh units of four types of ducks all reached 72 or more.Although there was significant positive correlation between egg-white weight and egg yolk weight (P<0.01),significant negative correlation was existed between egg-white weight and egg yolk ratio (P<0.01).There were significant negative correlations between egg specific gravity and egg yolk weight (P<0.05) and egg yolk ratio (P<0.05).In conclusion,the mode of cage feeding and the breed with green shell were appropriate choices in laying-egg duck production for high egg quality.     

Genetic parameters of the thick-to-thin albumen ratio and egg compositional traits in layer-type chickens

ABSTRACT

1. Generating a robust egg albumen is one of the major factors contributing to interior egg quality owing to its nutritive value and superior appearance. However, the genetic factors regulating the proportion of thick albumen are poorly understood.

2. In this study, 1330 eggs were collected from 450 Rhode Island White layers, aged 40 weeks, to measure egg compositional traits for three successive days. The restricted maximum likelihood method was applied to estimate genetic parameters for the thick-to-thin albumen ratio and other egg compositional traits. A univariate animal model was fitted to calculate heritability for each trait.

3. The heritabilities of egg weight, yolk weight, albumen height, Haugh units, percentages of yolk, thick albumen, thin albumen and the thick-to-thin albumen ratio were 0.32, 0.34, 0.28, 0.47, 0.61, 0.39, 0.31, and 0.45, respectively. The percentage of thick albumen was negatively correlated genetically with all traits, and percentage of thin albumen was negatively correlated genetically with all traits except for Haugh units. The thick-to-thin albumen ratio was positively correlated genetically with egg weight, albumen height and Haugh units, with correlations ranging from 0.21 to 0.54.

4. The results indicated that the percentage of thick albumen and the thick-to-thin albumen ratio were found to be moderately to highly heritable, and selection for the thick-to-thin albumen ratio could be conducive to the improvement of egg albumen quality.     

Egg production and quality under three housing systems in the tropics

The aim of this study was to evaluate egg production and quality of Rhode Island Red (RIR) laying hens in an outdoor system in the subhumid tropic. Eighty RIR laying hens were measured in two periods and housed randomly under three treatments: outdoor (O), indoor (I) and in conventional cages (C). Egg weight (55.88, 53.76 and 57.16 g, for O, I and C, respectively), food intake/hen/day (138.94, 129.74 and 162.90 g, for O, I and C, respectively) and food efficiency (3.13, 3.22 and 3.96 for O, I and C, respectively) were significantly (P < 0.05) influenced by housing system; however, both egg production and final body weight were not different (P > 0.05). Yolk colour (10.76, 9.94 and 10.08 colour scale, for O, I and C, respectively), albumen weight (92.63, 92.28 and 90.08 g, for O, I and C, respectively) and yolk weight (15.19, 14.61, 15.48 g for O, I and C, respectively) were significantly (P < 0.05) influenced by housing system, but albumen height, Haugh units and egg shell weight remained similar (P > 0.05). Under the conditions of this study, outdoor egg production seems to be a sustainable system comparable to the commercial type based on wired cages.     

Modelling the changes in the proportions of the egg components during a laying cycle

1. As hens age, egg weight increases but the eggs contain proportionally more yolk and less albumen and shell. However, at a given age, larger eggs contain proportionally more albumen. When modelling the nutrient requirements of the hen over a production cycle, based on the daily outputs of each nutrient, egg weight needs to be predicted as the sum of the three components, since each has a unique chemical composition, and these proportional changes will therefore influence the nutrient requirements of the hen. 2. Yolk weight is related to hen age and may be calculated using a logistic or Gompertz function. Allometric functions are used to predict albumen weight from yolk weight and shell weight from the weight of the egg contents. 3. A mechanistic, stochastic population model for layers may be used to verify that these functions correctly reflect the proportional changes in the egg components with advancing hen age and at a given age, over a range of egg weights. 4. The various parameters used in the equations need to be defined for the available genotypes.     

Comparisons of egg quality traits,egg weight loss and hatchability between striped and normal duck eggs

1. The egg quality of striped and normal duck eggs was compared to determine why striped eggs show decreased hatchability. A total of 430 eggs, obtained from a Pekin duck breeder flock aged 50–65 wks, were used in three experiments. The eggs were weighed and assigned randomly to measure egg quality traits, egg weight (EW) loss and hatchability during incubation.

2. There were no significant differences between egg types in terms of egg shape index, eggshell strength and thickness, albumen height, Haugh unit, yolk colour, weight of the eggshell with or without membranes, calcium, phosphorus, copper and manganese contents in the eggshell (with the inner and outer membranes or without the inner membrane), albumen weight, dry matter of albumen, crude protein (CP) of thick albumen and pH of the thick albumen.

3. The weight of eggshells with membranes, weight of thick albumen and CP of thin albumen in striped eggs were lower than those in normal eggs.

4. The thin albumen in striped eggs was heavier than that in normal eggs. The pH of the thin albumin in striped egg was significantly higher than that in normal eggs.

5. There were no significant differences in EW loss during incubation or duckling weight between striped and normal eggs. However, the hatchability of striped eggs was lower.

6. The lower weight of the eggshell inner membrane and thick albumen, lower CP content and higher pH in the thin albumen of striped eggs might contribute to lower hatchability.     

Effect of age of the laying hen on the composition of the egg

1. All eggs laid by a group of 16 light‐body‐weight hens during the laying year were weighed and divided into yolk, albumen and shell and the wet and dry weights of the components determined.

2. After an initial period of about 2 months, the weights of egg, water, wet albumen, wet and dry yolk increased with age, whereas those of dry albumen and wet and dry shell remained constant. Dry shell per square centimetre surface area decreased with age but water per square centimetre surface area remained constant.     

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.     

Influence of dietary energy, supplemental fat and linoleic acid concentration on performance of laying hens at two ages

1. The aim of this study was to investigate the influence of metabolisable energy (ME), supplemental fat (SFAT) and linoleic acid (LIN) content of the diet on the productive performance and weight of eggs and egg components of Isabrown hens of 22 or 74 weeks of age. 2. Six diets were formulated to contain the following concentrations of ME (MJ/kg), SFAT (g/kg) and LIN (g/kg), respectively: A) 11.8, 0 and 11.5; B) 11.8, 40 and 11.5; C) 11.8, 40 and 16.5; D) 11.2, 40 and 16.5; E) 11.2, 40 and 11.5; and F) 11.2, 0 and 11.5. Data were collected for 28 d and analysed using linear contrasts to test the effect of SFAT, LIN, ME and their interactions. 3. When the LIN content of the diets was maintained constant at 11.5 g/kg, an increase in the SFAT from 0 to 40 g/kg increased egg weight (63.8 vs 64.5 g; P<0.05), food intake (119 vs 124 g; P<0.01) and energy intake (1.36 vs. 1.42 MJ/d; P<0.01) and body weight change of the hens (-85 vs. 27 g; P<0.001). Supplemental fat also increased yolk (15.8 vs. 16.3 g; P<0.001) and albumen weight (40.8 vs. 42.3 g; P<0.01) but yolk to albumen ratio was not modified. 4. Egg and albumen weights were improved by SFAT in early but not in late producing hens. As a result, yolk to albumen ratio decreased in the younger hens, from 0.371 to 0.357, but increased in the older hens, from 0.408 to 0.415; P<0.01) with fat addition. 5. An increase in the LIN content of the diets from 11.5 to 16.5 g/kg did not modify any of the traits studied. 6. It was concluded that the LIN requirement of the hens for maximal productivity and weight of eggs is 11.5 g/kg or less. Supplemental fat increased the weight of eggs and albumen in the younger but not in older hens and the beneficial effect was independent of its LIN content.