Shell Quality Research Articles

Influence of catechin (flavan-3-ol) addition to breeder quail (Coturnix coturnix japonica) diets on productivity, reproductive performance, egg quality and yolk oxidative stability

ABSTRACTThe aim of this study was to investigate the effect of green tea (Camellia sinensis) catechin addition to breeder quail (Coturnix coturnix japonica) diet on productivity, reproductive performance, egg quality and yolk malondialdehyde (MDA) levels during storage, and some serum biochemical parameters. In this study, a total number of 180 quail, 7 weeks of age were randomly divided into 3 groups (1 control group and 2 treatment groups) with 5 replicates (9 females + 3 males). The control group was fed basal diet; the treatment groups were fed basal diet with 0.2% and 0.4% catechin supplementation for 5 weeks. The results of this study showed that 0.2% and 0.4% catechin addition had no significant effects on live weight, feed intake, egg production, feed efficiency, and egg internal quality (yolk colour, albumen index, yolk index, Haugh units, and pH) (P > .05). Catechin addition reduced egg weight, egg specific gravity, and egg shell thickness (P < .001). The catechin addition to diet significantly diminished MDA concentrations of eggs (P < .05). Serum glucose and triglyceride levels significantly decreased (P < .05) in the 0.4% catechin group, but were not significantly affected (P > .05) in the 0.2% catechin group compared to the control group. The addition of 0.2% catechin significantly increased fertility (P < .05), hatchability (P < .01), and the hatchability of fertile eggs (P < .05). In conclusion, catechin supplementation to breeder quail diet has the potential to increase egg shelf-life and reproductive performance. On the other hand, supplementation with these catechin levels decreased egg weight and egg shell quality.

Eggshell color in brown-egg laying hens — a review

The major pigment in eggshells of brown-egg laying hens is protoporphyrin IX, but traces of biliverdin and its zinc chelates are also present. The pigment appears to be synthesized in the shell gland. The protoporphyrin IX synthetic pathway is well defined, but precisely where and how it is synthesized in the shell gland of the brown-egg laying hen is still ambiguous. The pigment is deposited onto all shell layers including the shell membranes, but most of it is concentrated in the outermost layer of the calcareous shell and in the cuticle. Recently, the genes that are involved in pigment synthesis have been identified, but the genetic control of synthesis and deposition of brown pigment in the commercial laying hen is not fully understood. The brown coloration of the shell is an important shell quality parameter and has a positive influence on consumer preference. The extent of pigment deposition is influenced by the housing system, hen age, hen strain, diet, stressors, and certain diseases such as infectious bronchitis. In this article, the physiological and biochemical characteristics of the brown pigment in commercial brown-egg layers are reviewed in relation to its various functions in the poultry industry.

Evaluating the Effects of Salicornia Extract on Performance, Egg Quality and Blood Profile of Laying Hens

The current experiment was conducted to evaluate the effects of adding Salicornia extract to the drinking water on the performance, egg quality, and blood profile of laying hens. A total of 216 Hy-Line Brown laying hens at 40 weeks of age were used in a 10-week experiment. The birds were allotted into three experimental treatments with three replications per treatment and 24 birds per replication. The treatments were CON (basal diet), T1 (1 cc of Salicornia extract per liter of drinking water), and T2 (5 cc of Salicornia extract per liter of drinking water). The collected data were analyzed using the SAS package program. The results indicated that addition of Salicornia extract to the drinking water of laying hens did not cause any negative effects on the performance, egg quality, or blood profile. Compared to the control treatment, the treatments with Salicornia extract remarkably increased egg production (P<0.05) in the last week of the study, improved egg shell thickness and significantly reduced the egg breaking rate (P<0.05). The results of this study showed that the addition of Salicornia extract improved egg shell quality; thus, Salicornia extract can decrease the egg breaking rate and increase production on commercial farms.

Efeito da idade, peso do ovo e sistema de armazenagem sobre as propriedades físicas de ovos de poedeiras leves

A total of 72 eggs from a group of 100 white laying hens housed in standard cages were analyzed. Thirty-six eggs were retired when the hens had 44 week of age and the other 36 eggs were retired eight weeks afterwards. Each group of 36 eggs was radomly divided in three groups of 12 eggs. First group was analyzed at once (storage system C); second one was kept during one week in the refrigerator (5ºC) (storage system R), and third group were kept also one week but on ambient temperature (25ºC) (storage system ET). The hen age, egg weight and storage system had not significant (P&gt;0.05) effect on shell thickness. The specific gravity (SG) has a positive relation with shell quality. The egg class and storage system significantly (P

The impact of feeding supplemental chelated trace minerals on shell quality, tibia breaking strength, and immune response in laying hens

The objective of this study was to investigate the impact of long-term inclusion of the trace elements zinc, copper, and manganese chelated with the hydroxy analogue of methionine on layer performance, eggshell quality, tibia breaking strength, and immune response. A total of 216 Hy-Line W-36 laying hens were allocated to 6 treatments with 36 pens/treatment and 1 hen/cage using a randomized complete block design. There were 6 treatments with supplemental Zn-Cu-Mn, as follows: T1 0-0-0 ppm, T2 20-5-20 ppm as sulfates, T3 20-5-20 ppm as chelates, T4 40-10-40 ppm as sulfates, T5 40-10-40 ppm as chelates, and T6 80-10-80 as sulfates. The feeding of dietary treatments started at wk 24 pullet age and measurements of the key parameters were made from wk 44 to 80. Overall results (one-way ANOVA) indicated a significant treatment effect (P < 0.05) for shell thickness (at wk 74). Hens fed either no supplemental trace minerals (T1) or lower levels of supplemental inorganic trace minerals (ITM) (T2) had lower (P < 0.05) shell thickness when compared to high levels of sulfates (T6). Supplemental minerals as chelates at lower levels (T3) resulted in comparable (P > 0.05) response to T1 and T6 but different (P < 0.05) from T2. Factorial analysis of the data showed an improvement in shell breaking strength (P < 0.05 at wk 68), shell thickness (P = 0.08 at wk 68; P = 0.03 at wk 74), tibia breaking strength (P = 0.07) and antibody (Ab) titers to SRBCs (P < 0.05 at wk 63; 1 wk after secondary antigen challenge) in hens fed chelated trace mineral when compared to inorganic trace minerals. In summary, feeding laying hens’ diets containing supplemental chelated trace minerals showed improvements in eggshell thickness and immune response when compared to inorganic salts at specific time points measured during the latter part of the laying cycle.

Effects of supplementing microalgae in laying hen diets on productive performance, fatty-acid profile, and oxidative stability of eggs

The purpose of this trial was to investigate the effects of adding graded levels of dehydrated, whole-cell microalgae (All-G-RichTM, Alltech Inc.) in layer diets on the performance, egg and shell quality, yolk color, oxidative stability, and fatty-acid concentration of eggs. Six replicate groups of 5 Hy-Line W-36 laying hens were assigned to each of 4 dietary treatments. Treatments consisted of feeding a corn-soybean meal control diet alone or supplemented with 1.0, 2.0, or 3.0% All-G-RichTM during a 32-wk production period. Fatty-acid content of egg yolk was analyzed after feeding the experimental diets for 4 wk. The docosahexaenoic acid (DHA) content in egg yolk was linearly increased (P < 0.01) with increasing levels of algae in the diet. There was no effect of dietary treatments on production performance of layers in the entire trial period. Egg weight and eggshell quality were not affected by dietary treatments. Supplements of 2 or 3% All-G-RichTM significantly increased redness (a*) and decreased lightness (L) of egg yolk. Yolk fatty-acid oxidation, as measured by thiobarbituric acid reactive substances (TBARS), was not affected by treatments in eggs stored up to 30 d at 4°C. Based on these data, adding All-G-RichTM in layer diets can produce DHA-enriched eggs with no negative impact on egg quality.

Organic egg production. II: The quality of organic eggs is influenced by hen genotype, diet and forage material analyzed by physical parameters, functional properties and sensory evaluation

The purpose of the study was to determine, how the dietary nutrients available in organic egg production, and especially how the obligatory forage material in relation to two different hen genotypes affects the quality of organic eggs evaluated by physical, functional and sensory properties. The experimental treatments were subjected to a total of 1200 hens, which were of two hen genotypes, representing a high egg yielding hybrid; Lohmann Silver (LS), and a dual-purpose hen genotype; New Hampshire (NH). They were fed three experimental feed diets (A, B and C), which were intended to differ in protein contents, hence methionine contents. Protein content of diets A, B and C were on average 203, 199, and 182g/kg dry matter, respectively, and methionine content were on average 3.9, 3.1, and 3.0g/kg dry matter, respectively. Furthermore, two forage material treatments were supplied (maize silage+carrots and alfalfa silage), altogether distributed in a complete randomized design with 4 replicate pens each of 25 hens. Each replicate pen had a separate house and outdoor hen yard of 4m2/hen. Eight times during the experimental period, from 22 to 41 weeks of age, eggs were collected for analysis of egg weight, egg dimensions, shell strength, egg yolk colour, carotenoid content of yolk, albumen pH, albumen DM, and albumen gel textural properties. Twice during the study, boiled eggs were evaluated for sensory properties. The results showed the hen genotype significantly influenced all analyzed egg quality parameters. Furthermore, the nutrient content of the diets significantly affected the egg weight and dimension, the shell fracture force, egg yolk colour, and carotenoid content. The forage material type also affected the egg quality. Feeding the alfalfa silage resulted in eggs of higher weight, no effect on shell quality, egg yolk colours of higher darkness, redness and yellowness, and a higher content of pigmenting carotenoids, but lower content of carotenes (α- and β-). No overall sensory differences of eggs from hens fed the two forage materials appeared, although some interaction effects were seen and are discussed.In conclusion, the egg quality in organic egg production is highly affected by the hen genotype, while further influence of the diet and forage material on the egg quality depends on the specific nutrients and compositions hereof.

Yearly shifts in shell quality for the hermit crab Pagurus longicarpus in coastal Massachusetts

Global warming is expected to result in milder New England winters. In this study we monitored changes in hermit crab shell quality at Nahant, Massachusetts, USA, at intervals during 17 yr between 1997 and 2014 for a single species of hermit crab Pagurus longicarpus occupying the shells of the intertidal periwinkle Littorina littorea. The incidence of hermit crabs occupying damaged shells, shells housing the symbionts Hydractinia, Crepidula plana, and C. convexa, and showing poor shell fit varied significantly among years. Shell quality was especially bad in the summer of 2012, following one of the warmest winters on record: more than 60% of the sampled hermit crabs were found living in damaged shells and more than 50% of the shells bore symbionts. Moreover, an unusually low number (only 15%) of the hermit crabs sampled that summer were found in shells that were undamaged, without symbionts, and of adequate size, compared with 50 to 55% of hermit crabs being found in such 'perfect' shells in 1997 and 2013. We suggest that new, high-quality shells are added to hermit crab populations at our study site largely through the freeze-induced mortality of intertidal periwinkles, and that the poor shell quality documented in summer 2012 reflects reduced periwinkle mortality during the unusually warm preceding winter. If so, then P. longicarpus might serve as a coastal 'canary in the coal mine': documenting yearly shifts in the quality of shells used as shelters by coastal marine hermit crabs in New England may provide a convenient means of monitoring the impact of climate change on intertidal populations.

Low pH affects survival, growth, size distribution, and carapace quality of the postlarvae and early juveniles of the freshwater prawn Macrobrachium rosenbergii de Man

Acidification of rain water caused by air pollutants is now recognized as a serious threat to aquatic ecosystems. We examined the effects of low pH (control pH 7.5, pH 6, pH 5, pH 4) on the survival, growth, and shell quality of Macrobrachium rosenbergii postlarvae and early juveniles in the laboratory. Hatcheryproduced postlarvae (PL 5) were stocked at 250 PL per aquarium, acclimated over 7 d to experimental pH adjusted with hydrochloric acid, and reared for 30 d. Dead specimens were removed and counted twice a day. After 27 d rearing, all specimens were measured for total length and body weight. Carapace quality was assessed by spectrophotometry. Survival of juveniles was highest at pH 6 (binomial 95% confidence interval 79 - 89%) followed by control pH 7.5 (56 - 68%) and pH 5 (50 - 60%) and was lowest for unmetamorphosed postlarvae and juveniles at pH 4 (43 - 49%). The final median total length and body weight of juveniles were similar at control pH 7.5 (18.2 TL, 50.2 mg BW) and pH 6 (17.7 mm TL, 45.0 mg BW) but significantly less at pH 5 (16.7 mm TL, 38.2 mg BW); at pH 4, the postlarvae did not metamorphose and measured only 9.8 mm TL, 29.3 mg BW. Length frequency distribution showed homogeneous growth at pH 6, positive skew at control pH 7.5 and pH 5, and extreme heterogeneity at pH 4. The carapace showed different transmittance spectra and lower total transmittance (i.e. thicker carapace) in juveniles at pH 7.5, pH 6, and pH 5 than in unmetamorphosed postlarvae and juveniles with thinner carapace at pH 4. Thus, survival, growth, size distribution, and carapace quality of M. rosenbergii postlarvae and early juveniles were negatively affected by pH 5 and especially pH 4. The thinner carapace of the survivors at pH 4 was mostly due to their small size and failure to metamorphose. Natural waters affected by acid rain could decimate M. rosenbergii populations in the wild.

Apoptosis induction and release of inflammatory cytokines in the oviduct of egg-laying hens experimentally infected with H9N2 avian influenza virus

The H9N2 subtype avian influenza virus (AIV) can cause serious damage to the reproductive tract of egg-laying hens, leading to severe egg-drop and poor egg shell quality. However, previous studies in relation to the oviductal-dysfunction resulted from this agent have not clearly been elucidated. In this study, apoptosis and pathologic changes in the oviducts of egg-laying hens caused by H9N2 AIV were evaluated. To understand the immune response in the pathogenic processes, 30-week old specific pathogen free (SPF) egg-laying hens inoculated with H9N2 subtype of AIV through combined intra-ocular and intra-nasal routes. H9N2 AIV infection resulted in oviductal lesions, triggered apoptosis and expression of immune related genes accompanied with infiltration of CD3+CD4+ and CD3+CD8α+ cells. Significant tissue damage and apoptosis were observed in the five oviductal parts (infundibulum, magnum, isthmus, uterus and vagina) at 5 days post-inoculation (dpi). Furthermore, immune-related genes, including chicken TLR3 (7, 21), MDA5, IL-2, IFN-β, CXCLi1, CXCLi2, XCL1, XCR1 and CCR5 showed variation in the egg-laying hens infected with H9N2 AIV. Notably, mRNA expression of IFN-α was suppressed during the infection. These results show distinct expression patterns of inflammatory cytokines and chemokines amongst segments of the oviduct. Differential gene expression of inflammatory cytokines and lymphocytes aggregation occurring in oviducts may initiate the infected tissue in response to virus replication which may eventually lead to excessive cellular apoptosis and tissue damage.

Long-term recovery of clutch size and egg shell quality of the pied flycatcher (Ficedula hypoleuca) in a metal polluted area

We explored if breeding parameters and egg shell quality of an insectivorous passerine, pied flycatcher Ficedula hypoleuca, have fully recovered after c.a. 99% decrease in dust emissions from a non-ferrous smelter in the course of the 23 year study period. Some potentially important population characteristics (density, phenology, age) and environmental variables (habitat, inter-specific competition) were taken into account in the analysis. We found marked increase in reproductive parameters (egg shell quality, clutch size, hatchability, and fledgling number) in the metal polluted area especially in 1990's when metal-rich dust emissions from the smelter were markedly reduced. Still clutch sizes and fledgling numbers remain below the levels of the reference area. There is currently very little evidence of direct toxic effects of metals in our study population but full recovery of breeding parameters may not be reached until the full recovery of food chains, which is likely to be a slow process.

Mature Turkey Breeder Hens Exposed to Pandemic Influenza H1N1: Resultant Effects on Morbidity, Mortality, and Fecundity.

During the artificial insemination process, turkey breeder hens may become infected with influenza virus acquired from humans. The virus has been shown, through experimental infection, to localize in the reproductive tract, with limited dissemination in other tissues. A limited number of hens were used during these studies, and the overall flock morbidity, mortality, and fecundity were not able to be determined. The current case follows the progression of clinical signs in a flock of commercial breeder hens from onset of egg production losses in one house through the subsequent drops in four remaining houses. Each house contained approximately 3000 hens and followed a sequential loss of shell quality, reduced numbers of eggs, and fertility, while mild clinical signs were observed and mortality was slightly increased in a house with concurrent fowl cholera (Pasturella multocida) infection.

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.

&lt;b&gt;Effect of protease supplementation on production performance of laying hens

The experiment was conducted with the objective of evaluating the effect of protease enzyme supplementation on performance parameters and quality shell of laying hens. We used 240 Isa Brown commercial laying hens with 44 weeks of age. A completely randomized split-plot design (5 periods of 21 days) with four treatments and six replications (10 hens per replication) was used. The experimental diets were formulated according to the requirements of the breed. The following parameters were evaluated: egg production, feed intake, feed conversion, average egg weight, egg loss, specific gravity, percentage and shell thickness. After collection, the data were analyzed with SISVAR Statistical Package, and the means compared by SNK test at 5% probability. It was concluded that supplementation of diets low in nutrients with 500 g ton -1 of protease (100 U g -1 ), provides egg production and feed conversion rates similar to those obtained in laying hens fed diet with the nutritional level recommended for the breed. However, protease supplementation did not show effect on egg shell quality.

Impact of vaccination on infection with Vietnam H5N1 high pathogenicity avian influenza virus in hens and the eggs they lay

High pathogenicity avian influenza virus (HPAIV) infections in chickens negatively impact egg production and cause egg contamination. Previously, vaccination maintained egg production and reduced egg contamination when challenged with a North American H5N2 HPAIV. However, Asian H5N1 HPAIV infection has some characteristics of increased pathogenicity compared to other H5 HPAIV such as more rapid drop and complete cessation in egg production. Sham (vaccinated at 25 and 28 weeks of age), inactivated H5N1 Once (1X-H5-Vax; vaccinated at 28 weeks of age only) and inactivated H5N1 Twice (2X-H5-Vax; vaccinated at 25 and 28 weeks of age) vaccinated adult White Leghorn hens were challenged intranasally at 31 weeks of age with 6.1 log10 mean embryo infectious doses (EID50) of clade 2.3.2.1a H5N1 HPAIV (A/chicken/Vietnam/NCVD-675/2011) which was homologous to the inactivated vaccine. Sham-vaccinated layers experienced 100% mortality within 3 days post-challenge; laid soft and thin-shelled eggs; had recovery of virus from oral swabs and in 53% of the eggs from eggshell surface (35%), yolk (24%), and albumin (41%); and had very high titers of virus (average 7.91 log10 EID50/g) in all segments of the oviduct and ovary. By comparison, 1X- and 2X-H5-Vax challenged hens survived infection, laid similar number of eggs pre- and post-challenge, all eggs had normal egg shell quality, and had significantly fewer contaminated eggs with reduced virus quantity. The 2X-H5-Vax hens had significantly higher HI titers by the day of challenge (304 GMT) and at termination (512 GMT) than 1X-H5-Vax hens (45 GMT and 128 GMT). The current study demonstrated that AIV infections caused by clade 2.3.2.1a H5N1 variants can be effectively controlled by either double or single homologous vaccination.

Egg shell and yolk quality characteristics of layers fed with sugarcane press residue in soya and fish based diets.

Aim:Sugarcane press residue (SPR), a by-product of sugarcane industry, which is rich in inorganic salts was assessed at different levels in both soya based and fish based diets of layers for egg shell and yolk quality characteristics.Materials and Methods:SPR was incorporated in 32-week-old white leghorn layer diets at 0%, 5%, 10% and 15% either in the soya based or fish based diets to form T1 to T8 diets, respectively. Each diet was offered to five replicates of four laying hens each constituting a total of one sixty birds kept for 84 days under colony cages.Results:Mean egg shell thickness obtained from eggs of experimental hens measured was 0.342, 0.329, 0.320, 0.322, 0.319, 0.332, 0.328 and 0.336 mm in T1 through T8 groups, respectively. About the main factor effects, both showed non-significant results. Similarly, influence of different treatment diets, in imparting colour to the yolks, was found to be non-significant (p>0.05) at different 28-day time intervals. Further, the average yolk index values ranged non-significantly from 0.360 (T6) to 0.383 (T4).Conclusion:The SPR can be incorporated into layer diet as a source of inorganic as well as organic nutrients without affecting its egg quality characteristics.

Estimation of dietary selenium requirement for Chinese egg-laying ducks

The purpose of this study was to estimate the selenium (Se) requirement of egg-laying ducks based on daily egg production and the selenoprotein glutathione peroxidase (Gpx). Five-hundred and forty laying ducks were divided into six treatments, each containing six replicates of 15 ducks. The birds were caged individually and received a Se-deficient basal diet (0.04 mg/kg) or diets supplemented with 0.08, 0.16, 0.24, 0.32, 0.40 mg/kg Se (as sodium selenite) for 6 months. The experiment consisted of two periods: an early-laying period of 2 months and the peak-laying period of 4 months. Egg production and feed intake were recorded daily. At the end of the experiment, blood samples were drawn for determination of Gpx activity in plasma (Gpx3) and in erythrocytes (Gpx1). Hepatic Gpx1 activity and relative expression of Gpx1 mRNA were also determined. Eggs (n = 6) were sampled for quality determination and Se content at the end of the experiment. The activities of plasma Gpx3, erythrocyte Gpx1 and liver Gpx1 increased in a quadratic manner (P &lt; 0.001) with increasing supplemental Se. The mRNA abundance of hepatic Gpx1 increased linearly (P &lt; 0.001) with dietary Se supplementation. Egg shell thickness was significantly reduced in the ducks fed 0.44 mg Se/kg (P &lt; 0.05), indicating that higher dietary Se tends to compromise egg shell quality. Yolk and albumen contents of Se increased linearly (P &lt; 0.0001) with dietary Se supplementation. Using quadratic broken line models, the Se requirement for daily egg production was 0.18 mg/kg for early-laying ducks and 0.24 mg/kg for peak-laying ducks; for optimal function of Gpx (peak-laying ducks), it was 0.37 mg Se/kg.

Dietary calcium deficiency in laying ducks impairs eggshell quality by suppressing shell biomineralization.

The objective of this study was to determine the effects of dietary calcium deficiency on the process of shell formation. Four hundred and fifty female ducks (Anas platyrhynchos) at 22 weeks were randomly assigned to three groups. Ducks were fed one of two calcium-deficient diets (containing 1.8% or 0.38% calcium, respectively) or a calcium-adequate control diet (containing 3.6% calcium) for 67 days (depletion period) and then all ducks were fed a calcium-adequate diet for an additional 67 days (repletion period). Compared with the calcium-adequate control, the average shell thickness, egg shell weight, breaking strength, mammillae density and mammillary knob thickness of shell from ducks that consumed the diet with 0.38% calcium were significantly decreased (P<0.05) during the depletion period, accompanied by reduced tibia quality. The mRNA expression of both secreted phosphoprotein 1 (SPP1) and carbonic anhydrase 2 (CA2) in the uterus was decreased after feeding calcium-deficient diets (1.8% or 0.38% calcium). mRNA transcripts of calbindin 1 (CALB1), an important protein responsible for calcium transport, and the matrix protein genes ovocalyxin-32 (OCX-32) and ovocleidin-116 (OC-116) were reduced in ducks fed 0.38% calcium but not 1.8% calcium. Plasma estradiol concentration was decreased by both of the calcium-deficient diets (P<0.05). The impaired shell quality and suppressed functional proteins involved in shell formation could be reversed by repletion of dietary calcium. The results of the present study suggest that dietary calcium deficiency negatively affects eggshell quality and microarchitecture, probably by suppressing shell biomineralization.

Egg shell quality in Japanese quail: characteristics, heritabilities and genetic and phenotypic relationships

The objective of the present study was to estimate heritabilities as well as genetic and phenotypic correlations for egg weight, specific gravity, shape index, shell ratio, egg shell strength, egg length, egg width and shell weight in Japanese quail eggs. External egg quality traits were measured on 5864 eggs of 934 female quails from a dam line selected for two generations. Within the Bayesian framework, using Gibbs Sampling algorithm, a multivariate animal model was applied to estimate heritabilities and genetic correlations for external egg quality traits. The heritability estimates for external egg quality traits were moderate to high and ranged from 0.29 to 0.81. The heritability estimates for egg and shell weight of 0.81 and 0.76 were fairly high. The genetic and phenotypic correlations between egg shell strength with specific gravity, shell ratio and shell weight ranging from 0.55 to 0.79 were relatively high. It can be concluded that it is possible to determine egg shell quality using the egg specific gravity values utilizing its high heritability and fairly high positive correlation with most of the egg shell quality traits. As a result, egg specific gravity may be the choice of selection criterion rather than other external egg traits for genetic improvement of egg shell quality in Japanese quails.

Effect of Calcium Sources and Particle Size on Performance and Eggshell Quality in Laying Hens

An experiment was conducted to determine the effect of different combination calcium sources and particle size on performance and egg shell quality in layer hens. In the experiment, 198 brown laying hens at 44 week of age were randomly assigned into 11 treatments groups. The experimental diets consisted of different calcium sources (Fine limestone, large limestone, large oyster shell and large egg shell) and their different combination. The experimental unit consisted of a groups of three hens, thus each treatment was replicated six times. Different calcium sources and particle size addition to the laying hens diet had no significantly effect on body weight gain, egg production, egg mass, feed intake, feed conversion ratio, egg specific gravity, egg shell weight, egg shell thickness and egg shell breaking strength but egg weight had significantly affected by the treatments. The significantly highest egg weight was found in laying hens fed with 50 % fine limestone and 50 % large limestone. Dietary different Ca sources had a significant effect on Ca, P and Mg as mineral contents of eggshell and tibia. In the present study, when dietary large calcium sources (limestone, oyster shell and egg shell) had no effect on performance and eggshell quality parameters in laying hens. However, dietary containing at least 50 % large calcium sources had positive effect on mineral contents of tibia.