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.     

Genetic variation for egg production,egg quality and bone strength in selected and traditional breeds of laying fowl

1. A multi-breed experiment was conducted with 25 commercial and traditional lines of laying fowl to determine the extent of between-breed genetic variation for adult body weight, sexual maturity, rate of lay, egg weight and egg composition to 55 weeks of age. The genetic variability for bone strength and eggshell strength was determined at 55 weeks of age and a comparison of commercially selected and traditional breeds was performed. 2. The proportion of the total variation that was associated with breed or line of origin was high (> 0.8) for body weight, sexual maturity and shell colour; moderately high (0.4 to 0.7) for rate of lay, early and late egg weight, weights of egg yolk, albumen and shell at 55 weeks; and low (< 0.4) for egg weight at 42 to 45 weeks, albumen quality and the number of egg inclusions. 3. There were no detectable differences between breed within category (traditional and commercial lines) for rate of lay, and estimates of breed variation for egg weight and egg components were substantially decreased within category compared with the overall analysis. 4. Commercial lines displayed earlier sexual maturity, greater rates and persistency of lay, and higher egg weights at earlier (32 to 35 weeks) and later (52 to 55 weeks) ages. At 55 weeks, the larger eggs from commercial birds contained more albumen of higher quality and paler yolks of similar weight to those from traditional breeds. The relative weight of the eggshell was similar in both categories. 5. There was considerable genetic variation between commercial lines for bone density and a moderate proportion of genetic variability for bone strength. Commercial lines had very weak bones compared with traditional lines but there was relatively little genetic variation for eggshell strength. The results suggest that eggshell quality is maintained in genetically selected lines at the expense of bone strength and bone radiographic density.     

The effects of dietary fat and bird age on the weights of eggs and egg components in the laying hen

1. A low-fat diet or an isoenergetic and isonitrogenous high-fat diet containing 55 g maize oil/kg were fed to laying hens at different stages during the laying year in two experiments. 2. Feeding the high-fat diet to young hens resulted in a rapid increase of 2.5 g in egg weight, made up of increases in both yolk and albumen weights. 3. Switching the diets at 50 weeks caused changes in egg weight that were accounted for entirely by changes in egg albumen weight. 4. Feeding the high-fat diet from 46 weeks in a second experiment increased egg and egg albumen weights by 1.26 and 1.34 g respectively. 5. The increase in egg weight with age was associated with a greater increase in the proportion of yolk, at the expense of albumen, compared to egg weight increases related to dietary fat. 6. It is concluded that dietary fatty acids increase egg weight by a mechanism different from that causing age-related increases in weight and that the mechanism involves a stimulation of oviduct protein synthesis.     

Effect of natural zeolite on yolk: Albumen ratio in hen eggs

1. The egg yolk: albumen (Y:A) ratio during the laying year was investigated in a commercial strain (Hisex) when natural zeolite was added to a layer's diet. 2. Dietary natural zeolite (NZ) increased both egg weight and albumen weight, while yolk weight was not significantly affected. 3. The Y:A ratio was less (more albumen) in eggs laid by hens on zeolite treatments. It was concluded that by feeding NZ it is possible to alter the Y:A ratio.     

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.     

Genetic relations of yolk proportion and chick weight with production traits in a White Leghorn line

1. The main purpose of this study was to estimate genetic correlations between yolk proportion, chick weight and production traits using an animal model. 2. Direct-direct genetic correlations were estimated between yolk proportion and age at first egg (-0.34), body weight at 20 (0.10), 40 (0.58) and 60 (0.52) weeks of age, egg number (0.56), egg mass (0.59), feed intake (0.64) and feed conversion (-0.25). 3. Maternal-direct genetic correlations were estimated between chick weight and age at first egg (0.40), body weight at 20 (0.57), 40 (0.66) and 60 (0.56) weeks of age, egg number (-0.50), egg mass (0.21), feed intake (0.45) and feed conversion (0.17), respectively. 4. In conclusion, the results suggest that selection on a higher yolk proportion would not have any unfavourable effects on egg production. Maternal-direct genetic correlations between chick weight and production traits resembled direct-direct genetic correlations between egg weight and production traits found in other studies.     

Effect of daily feed intake in laying period on laying performance, egg quality and egg composition of genetically fat and lean lines of chickens

1. The objectives of this study were to evaluate the effects of feed intake on laying performance, egg quality and egg composition in a Fat line and a Lean line during the laying period (34 to 54 weeks of age). 2. The experiment was a 2 × 2 factorial design with two dietary intake levels (nutrition recommendation and 75% of recommendation) and two broiler genotypes (Fat line and Lean line). Hens (384 of each line) were randomly divided at 23 weeks of age into 4 treatments, with each treatment represented by 12 replicates of 16 birds each. The experiment started when the rate of lay reached 5% and continued until 54 weeks of age. 3. The results indicated that there was a significant interaction between daily feed intake and genotype on egg production, egg weight, percentage yolk, yolk/albumen ratio and yolk cholesterol content. Fat line hens produced significantly more eggs and had a lower incidence of cracked eggs than the Lean line hens. The reduction in feed intake decreased egg weight and increased egg production, egg-shape index and cholesterol content of yolk significantly.     

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.     

Effect of sweet green pepper on yolk color and performance of laying hens

An experiment was conducted to evaluate the effects of sweet green pepper (SGP) on the performance and egg quality of commercial laying hens. A total of 144 Hy Line W36 egg layers were randomly assigned to 4 treatments with 9 replicate groups of 4 hens each. Treatments consisted of the following diets: 1) basal diet (BD), 2) BD + 75 ppm SGP, 3) BD + 125 ppm SGP, 4) BD + 225 ppm SGP. The diets contained 2,730 kcal/kg metabolizable energy and 15.5% crude protein. Egg production and egg quality were monitored for 16 weeks. Feed intake, hen-day egg production, egg mass, and feed conversion per dozen were not significantly affected by the addition of SGP to the diets. The addition of 225 ppm of SGP decreased egg weight. Specific gravity, albumen height, Haugh unit, yolk weight, albumen weight, albumen percentage, and yolk yellowness (b*) were not significantly affected by the addition of SGP. The addition of SGP to the diets increased yolk percentage, yolk color using a Roche fan, and yolk redness (a*). Based on these data, SGP was shown to be a useful feed ingredient for laying hens; it can be included in diets without negative effects on performance and egg quality. However, owing to the depression of egg weight with the inclusion of SGP, it may be of interest to producers and industry to control egg size in old layers and possibly improve shell quality. The addition of SGP to the diets impacted yolk color and may be useful in specialty markets.     

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)。     

Use of L-carnitine and humate in laying quail diets

This experiment was carried out to determine the effects of using L-carnitine and humate alone or in combination in quail diets on laying performance, egg traits and blood parameters. A total of 280 Japanese quails aged 10 weeks, divided into one control group and three treatment groups, were used. The diets of the first, second and third treatment groups were supplemented with 100 mg L-carnitine/kg, 1.5 g humate (Farmagülat?r Dry Plus)/kg and 100 mg L-camitine + 1.5 g humate/kg, respectively. The experimental period lasted 16 weeks. The addition of L-carnitine and sodium humate alone or in combination did not significantly affect body weight, feed consumption, egg production, feed conversion ratio, mortality, egg-shell thickness, egg yolk index and the percentages of egg-shell, albumen and yolk. Egg weight increased (P < 0.001) with L-carnitine supplementation. The values of egg albumen height (P < 0.05), egg albumen index (P < 0.01) and egg Haugh unit (P < 0.05) were increased with humate supplementation. Egg cholesterol content and blood serum parameters were not affected by the supplementation of L-carnitine with or without humate. The results in this study demonstrated that L-carnitine supplementation increased egg weight while humate addition increased egg albumen index and egg Haugh unit of laying quails. However, the combined administration of L-carnitine and humate did not have any significant effects on the parameters measured.     

不同饲粮粗蛋白质水平下蝇蛆蛋白替代豆粕对蛋鸡生产性能、蛋清品质及血清蛋白质代谢指标的影响

本试验旨在研究不同饲粮粗蛋白质水平下蝇蛆蛋白替代豆粕对蛋鸡生产性能、蛋清品质及血清蛋白质代谢指标的影响。采用单因素试验设计,选取252只产蛋率、体重相近的健康33周龄罗曼白蛋鸡,随机分为3组,每组7个重复,每个重复12只鸡。各组分别饲喂标准回肠可消化氨基酸(SIDAA)平衡模式下配制的不同粗蛋白质水平(16.50%、14.85%、13.20%)的玉米-豆粕-蝇蛆蛋白饲粮,各组蝇蛆蛋白与豆粕提供等量的粗蛋白质。预试期2周,正试期12周。结果表明:1)与16.50%组相比,14.85%组的产蛋率、平均蛋重、产蛋量、平均日采食量和料蛋比均无显著差异(P>0.05);13.20%组的料蛋比显著增加(P<0.05),产蛋率、产蛋量、平均蛋重和平均日采食量均显著降低(P<0.05)。2)与16.50%组相比,14.85%组的平均蛋重、蛋清重、浓蛋白重、蛋白高度、哈氏单位和蛋清比例均无显著差异(P>0.05);13.20%组的平均蛋重、蛋清重、浓蛋白重和蛋白高度显著降低(P<0.05),而蛋清比例、哈氏单位无显著差异(P>0.05)。3)各组血清谷草转氨酶、谷丙转氨酶活性及总蛋白、白蛋白、尿酸含量无显著差异(P>0.05),且输卵管膨大部组织学形态正常。由此可见,在本试验条件下,使用蝇蛆蛋白替代豆粕并使饲粮粗蛋白质水平降低至14.85%时未对蛋鸡生产性能和蛋清品质产生不良影响,但饲粮粗蛋白质水平降低至13.20%时则会产生不利影响。     

Effects of housing system (outdoor vs cages) and age of laying hens on egg characteristics

1. Effects of two housing systems (cages vs outdoor) on external and internal egg characteristics were investigated. 2. In total 785 eggs from three different lines in cages and 268 eggs from outdoor-housed layers were examined for egg weight, albumen, yolk and shell content, albumen height and pH, and albumen and yolk dry matter content. 3. Interactions between layer age and housing systems were found for egg weight, eggshell content, albumen height, albumen pH, and dry matter content of the albumen and yolk. This was mainly due to the greater variation with age in the outdoor layers, compared to the caged layers. 4. Irrespective of age eggs from outdoor layers were relatively broader than eggs from the caged layers. Yolk colour was considerably darker in the outdoor group (11.0 vs 9.3). 5. We concluded that it is more difficult to maintain constant external and internal egg quality in an outdoor housing system than in a battery cage system. Factors that determine the greater fluctuations in internal egg quality need to be investigated.     

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.     

高产蛋鸡品系产蛋中后期蛋品质性状遗传规律的研究

为选育改良国产高产蛋鸡产蛋中后期蛋品质,确定合理的饲养周期。本研究选取北京市华都峪口禽业有限责任公司13世代Y1、K1品系蛋鸡,测定56、66、72、80周龄蛋重、蛋壳颜色、蛋壳强度、蛋白高度和蛋黄颜色,采用DMU软件估计遗传参数。结果表明:随着蛋鸡周龄增大,Y1、K1系蛋重显著提高(P0.05),蛋壳强度、蛋白高度和蛋黄颜色极显著下降(P0.01);Y1系和K1系56~80周龄各性状遗传力在0.03~0.52;品系内同一性状不同周龄之间高度遗传相关(0.57~0.99),同一周龄不同性状之间遗传相关(-0.39~0.43)和表型相关(-0.049~0.122)均较低。本研究表明高产蛋鸡纯系产蛋后期蛋品质随周龄增加有所下降,同一性状不同周龄之间高度相关,可以通过前期的选育提高后期蛋品质。     

Effects of supplemental L-carnitine in drinking water on performance and egg quality of laying hens exposed to a high ambient temperature

The present study was conducted to investigate effects of L-carnitine supplied with drinking water on performance and egg quality of laying hens under high environmental temperature. In the study, 47-week-old laying hens (Brown hisex) were divided into two groups (control and treatment) and fed with a standard layer diet. Treatment group was received 50 p.p.m L-carnitine with drinking water for an 8-week period. Throughout the study, 8 h hot (35-37 degrees C) and 16 h thermoneutral (20-22 degrees C) environmental temperature regime was employed daily. The results showed that L-carnitine supplementation affected some egg quality characteristics of layers under high environmental temperature. Relative albumen weight and height were increased (p < 0.05) by supplemental L-carnitine. Live weight gain, feed intake, egg mass, egg weight, yolk weight, shell weight, yolk index, egg-shape index, yolk colour score and shell thickness were not affected (p < 0.05) by L-carnitine. It is concluded that L-carnitine supplementation in laying hens could have potential to improve albumen quality under high environmental temperature.     

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.     

Estimation of genetic parameters based on individual and group mean records in laying hens

(1) The study was conducted to estimate the heritability, genetic correlations and breeding values of laying hens based on individual records and group mean records. (2) Records of two pure lines from a commercial breeding programme of White Leghorns from three generations housed in single cages and in group cages were used. A total of 8483 and 8817 individual records of lines A and D, respectively, and a total of 1358 (line A) and 1161 (line D) group mean records were analysed. (3) An animal model using Restricted Maximum Likelihood (REML) was used to estimate variance components of individual records. Group mean records were analysed using the sire model, taking heterogeneity of error variance and correlated residual effects into account. Breeding values of sires were estimated based on the BLUP method using a multivariate sire model. Spearman Rank correlations were used to compare sire breeding values estimated from individual records and from group mean records. The traits studied were monthly egg production, cumulative production and egg weight. (4) Heritability estimates based on individual records were higher than from group mean records. Heritabilities for cumulative production records were higher than for monthly production, based on individual as well as group mean records. The estimates of genetic correlations between monthly egg production and cumulative production were moderate to high. Egg production and egg weight recorded individually were highly genetically correlated with those recorded on group means. Sire breeding values estimated from individual records showed high correlations with those from group mean records. (5) Differences in the ranking of sire breeding values estimated from individual vs group mean records were negligible, indicating that no genotype x environment interaction exists. Selection based on individual performance records of laying hens housed in single cages could give a good response on performance of laying hens housed in group cages. Cumulative egg production over periods 1 to 6 is the best trait for the selection programme.     

Effects of supplementary iodine on the performance and egg traits of laying hens

1. This experiment was carried out to determine the effects of dietary iodine supplementation on the performance and egg traits of laying hens. A total of 600 SHSY type brown layers aged 21 weeks of age were chosen at random from a large flock. They were randomly distributed into 30 pens at 20 hens per pen. Each treatment comprised 6 replicates of 20 layers in groups of 5 birds. The diets were supplemented with 0, 3, 6, 12 and 24 mg/kg iodine as calcium iodate. The experimental period lasted 30 weeks. 2. There were no significant differences among the groups in body weight, food consumption, egg production, food consumption per kg eggs, eggshell index, eggshell breaking strength, shell thickness or egg yolk index. 3. Supplementation of the diet with 12 mg/kg iodine increased food consumption per dozen eggs compared to the groups fed on diets supplemented with 0 and 6 mg/kg iodine. 4. Egg weight was less in groups fed on diets supplemented with 12 and 24 mg/kg iodine than in the group receiving no iodine supplementation. 5. Iodine supplementation to provide 12 and 24 mg/kg reduced egg albumen index and egg Haugh units. 6. There were no significant differences among the groups in egg cholesterol and egg yolk cholesterol contents. 7. The iodine concentrations in egg yolk, egg albumen and whole egg increased with increased iodine supplementation. 8. As a result, the 3 and 6 mg/kg iodine supplementation of diet could be used to enrich the eggs with iodine without any adverse effect on performance and egg traits.     

肉种鸡屠体肥度性状与蛋物理组成关系研究

以肉种鸡为素材,测量其42周龄蛋的物理组成和54周龄肉种鸡腹脂重(率),研究肉种鸡屠体肥度与蛋物理组成关系。结果表明:腹脂重(率)与蛋重、蛋黄重、蛋黄比例、蛋黄蛋白比例相关不显著;蛋重与蛋黄重、蛋白重存在极显著的正表型相关,与蛋黄比例、蛋黄蛋白比例呈显著的负表型相关;蛋黄重与蛋白重呈极显著的正表型相关,与蛋黄比例、蛋黄蛋白比例呈极显著的正表型相关;蛋白重与蛋黄比例、蛋黄蛋白比例呈极显著的负表型相关;蛋黄比例与蛋黄蛋白比例呈极显著正表型相关。