The relationship between eggshell color, hatching traits, fertility, mortality, and some qualitative aspects of Japanese quail (Coturnix japonica) eggs

Abstract

Quail, one of the most important sources of meat and eggs, can aid in the reduction of the meat crisis if they are raised and cared for by small farmers. The current study investigated the impact of eggshell color variety on egg quality traits and hatching parameters of Japanese quail Coturnix japonica eggs. Therefore, 1,075 eggs were collected from female quails when they were 10-wk old. These eggs were distributed based on the color of their eggshells into 5 different classifications: eggshell with color type 1, very dark distributed brown spots on brown eggshell; eggshell with color type 2, small black spots on a white eggshell; eggshell with color type 3, widespread brown spots on brown eggshell; eggshell with color type 4, bubble egg, pin dotted on grayish brown color eggshell; and eggshell with color type 5, small brown spots on very clearly white eggshell. The characteristics of hatchability, internal and external egg quality, and the rate of embryonic death were then determined. The results showed that the percentage of fertility and commercial and scientific hatchability was greatly affected by eggshell color. There were also variations in the percentage of hatched chicks', early mortality rates, and late mortality rates based on eggshell color. According to the results of the current study, eggshell color has a significant impact on egg weight, egg width, and percentages of eggshell, yolk, and albumen but has no effect on shape index, egg length, or egg elongation. Based on the results, eggshells with color types 2 and 3 were recommended for use in hatching procedures due to their high levels of fertility (92.01 and 91.63%, respectively), scientific hatchability (82.92 and 83.93%, respectively), commercial hatchability (76.56 and 77.32%, respectively), and hatched chick (5.50 and 6.70, respectively). In addition, the late embryonic mortality rate was 0.00% for eggshells with color type 3. Therefore, the color of the eggshell can be employed as a key factor in guiding the eggs that are produced, whether they are going to be consumed at the table or used for hatching, to make breeding easier.

INTRODUCTION

From an economic standpoint, the Japanese quail (Coturnix japonica) is one of the most important birds in the poultry sector because of its rapid development, effective reproductive potential, short life cycle, excellent disease resistance, and early sexual maturity (Batool et al., 2023). Japanese quails are also commonly used due to the medicinal properties of their meat and eggs (Alaşahan et al., 2015; Naımatı et al., 2022).

The color of the eggshell is determined by the presence of 3 primary dyes: protoporphyrin, biliverdin, and zinc chelate. These 3 dyes, when combined in various ways, make every conceivable shade of shell (Inyinbor et al., 2023). Eggs laid by quails can have a variety of shell colors, including white, blue, or green, and their spots can be a variety of sizes and colors (Alaşahan et al., 2015). Quail eggs of various colors and patterns, including white, sandy-spotted, light-spotted, heavily-spotted, and/or moderately-spotted, were separated into groups by Okumus and Durmus (1998).

The surface pigment (porphyrin) of the quail eggshell accumulates in the uterus during egg creation and is created 2 to 3 h before oviposition (Woodard and Mather, 1964; Poole, 1965; Tanaka et al., 1977; Soh et al., 1989). In addition, the shell gland's mucous epithelium contains pigment granules in its apical cells (Tamura et al., 1965; Tamura and Fujii, 1966; Poole, 1967). When observing the deposition of pigment onto a quail eggshell through the shell gland wall, a naked-eye observation reveals that the shell is spotted with pigments at the beginning of the deposition and that the deposition of bulky pigments suddenly occurs 20 min after the beginning of the deposition (Tanaka et al., 1977).

About 4 h after being released from the ovary, the ovum travels to the shell gland pouch, where it is fertilized, encased in albumen, and protected by a limiting membrane (Board and Sparks, 1991). Pigments, which give eggs their color and pattern, are deposited in the cuticle and outer layer of the shell 4 h before egg-laying (Burley and Vadehra, 1989; Soh et al., 1993).

Colors of a brownish tint are generated by protoporphyrin, while blue and green are generated by biliverdin IXa and its zinc chelate (Burley and Vadehra, 1989; Cherry and Bennett, 2001). It has not yet been determined which materials in eggshells reflect UV light based on their structures or hues, however, this phenomenon is well-documented (Kennedy and Vevers, 1976; Burley and Vadehra, 1989; Cherry and Bennett, 2001). When evaluating table eggs and hatchlings, the eggshell quality is the primary consideration (Aygun, 2014).

There is a correlation between eggshell color and shell quality. White to celadon eggs were found to be less favorable for eating, hatching, and general egg quality by breeders. However, it has been suggested that the weight and hatchability of an egg can be affected by its shell color (Drabik et al., 2020).

The success of a quail egg's embryo in hatching and its rate of development are both influenced by the egg's morphology (Alasahan et al., 2016). It has been demonstrated that there is a link between the level of shell pigmentation, the thickness of the shell, and the ability of the bird to hatch, implying that the processes of shell pigmentation and calcification may be positively correlated (Ingram et al., 2008).

Therefore, the current study aims to investigate how the color of the eggshell affects the characteristics of quail eggs (C. japonica), including the birds' fertility, hatching success, and embryonic mortality. Furthermore, this research aims to help breeders make decisions when selecting eggs for hatching.

MATERIALS AND METHODS

Experimental Design

The research was carried out in the Faculty of Agriculture, Zagazig University, Sharqia Governorate, Egypt, in the quail breeding unit using Japanese quail (C. japonica).

To evaluate egg quality and hatching parameters, a total of 1,075 eggs were used. The quail reared were separated into battery cages. Each cage holds 1 male and 2 females in a 1:2 sex ratio.

Collection of Eggs

Quail eggs were collected from their battery cages every day. The study did not include eggs with irregularly shaped, cracked, unclean, or white shells. Eggs were collected from a 10-wk-old Japanese quail. When shooting photographs of the eggs that were to be included in each of the categories, identical conditions were applied. The images were captured with a digital camera at 20 cm during the day to maximize transparency.

To ensure a clear color distinction between the groups, each egg was photographed from one side, then turned 180° and photographed again. The images were examined with a Delphi-based application, and due to the variances in the size and shape of the eggs, a rectangular region representing most of the eggs studied was chosen. The method employed categorized eggs into numerous classes based on their eggshell color (Sezer and Tekelioglu, 2009; Alaşahan et al., 2015; Drabik et al., 2020; Lan et al., 2021). Eggs were classified based on the color of the shell and the color of the spots on them after careful analysis and study of prior studies closely related to the subject of the study (Drabik et al., 2020; Lan et al., 2021).

After carefully examining each quail egg using the categorical classification of the eggshell patterns of Japanese quails, 5 distinct groups were established according to the eggshell color and the presence or absence of spots. Both the external and internal features of the eggs as well as hatching data, were analyzed. Table 1 and Figure 1 list the names of the study groups as well as the number of eggs in each. The 5 different classifications were as follows, eggshell with color type 1, very dark distributed brown spots on brown eggshell; eggshell with color type 2, small black spots on a white eggshell; eggshell with color type 3, widespread brown spots on brown eggshell; eggshell with color type 4, bubble egg, pin dotted on grayish brown color eggshell; and eggshell with color type 5, small brown spots on very clearly white eggshell.

Table 1.

The number of eggs and the number of hatched eggs in commercial Japanese quails (Coturnix japonica) based on eggshell colors and eggshell spots.

Parameters	Eggshell with color type 1	Eggshell with color type 2	Eggshell with color type 3	Eggshell with color type 4	Eggshell with color type 5
Characteristics	Very dark distributed brown spots on brown eggshell	Small black spots on white eggshell	Widespread brown spots on brown eggshell	Bubble egg = pin dotted on grayish brown color eggshell	Small brown spots on very clearly white eggshell
Number of eggs	67	60	68	40	80
Number of hatched eggs	165	135	159	108	193

Number of eggs = The total number of eggs used to determine the quality characteristics of each group.

Number of hatched eggs = The number of eggs from each group that began the hatching process.

Figure 1.

Classifications of Japanese quail (Coturnix japonica) eggshell colors and spots in the current study. (A) eggshell with color type 1, very dark distributed brown spots on brown eggshell; (B) eggshell with color type 2, small black spots on a white eggshell; (C) eggshell with color type 3, widespread brown spots on brown eggshell; (D) eggshell with color type 4, bubble egg, pin dotted on grayish brown color eggshell; and (E) eggshell with color type 5, small brown spots on very clearly white eggshell.

External Characteristics of Egg Quality

During the current study, a total of 315 eggs were collected to investigate the overall quality of the eggs based on the colors of their eggshells (Table 1 and Figure 1). A digital display scale with sensitivity ranging from 0.01 g to 600 g was utilized for the purpose of determining the weight of the eggs (Brecknell MBS Economic Precision Balance, Fairmont, MN).

To measure the width and length of the eggs, a digital Mitutoyo vernier calipers (Mitutoyo Corporation, Kanagawa, Japan) was used. The external egg quality characteristics such as egg shape index, shell ratio, and elongation were determined as previously described by Ahmed (2022).

Internal Characteristics of Egg Quality

The first step consisted of cracking open each egg onto a piece of flat glass. In the second step, the diameter and height of the egg yolk and albumen were measured. This was done with the aid of a digital caliper and an electronic balance with a precision of 0.01 g (Brecknell).

The albumen and yolk were separated from one another without causing any damage to the egg yolk, and the third process involved determining the weight of the egg yolk. The albumen and yolk percentages were used in the calculation of the internal egg quality values (Nasr et al., 2015).

Hatchability Traits

A total of 760 healthy Japanese quail eggs were used to analyze the correlation between eggshell color and hatching success. Eggs were utilized to assess fertility and hatchability rates in each color group.

The eggs were incubated in a single electric incubator containing 1,500 eggs. After the eggs were separated and labeled, they were placed in a plastic setter. Incubation was carried out at a temperature of 37.5°C and a relative humidity between 50 and 60%, and the eggs were rotated manually 3 times a day. After the incubation process, the electric incubator's settings were modified so that the relative humidity was increased to 73%, while the temperature remained unchanged at 37.5°C.

After that, the eggs were transferred to hatching nets and left in the hatching compartment for 17.5 d. The hatched chicks were sent to the house to be raised on the day of hatching, while the unhatched eggs were separated and tested for fertility, hatchability, and mortality rates. The number of fertile eggs, the number of embryos that died during the first incubation, and the number of healthy chicks hatched were all determined.

The following equations were utilized in the current study to determine the hatchability and fertility percentages of fertile and laid eggs (Genchev, 2012):

$$\text{Percentage}\text{of}\text{fertility}=\frac{\text{Number}\text{of}\text{fertilized}\text{eggs}}{\text{Number}\text{of}\text{eggs}\text{placed}\text{in}\text{the}\text{setter}}\times 100$$ (1)

$$\text{Hatchability}\text{of}\text{fertile}\text{eggs}\left(\text{Percentage}\text{of scientific}\text{hatchability}\right)=\frac{\text{Number}\text{of}\text{hatched}\text{chicks}}{\text{Number}\text{of}\text{fertilized}\text{eggs}}\times 100$$ (2)

$$\text{Hatchability}\text{of}\text{all}\text{eggs}\left(\text{Percentage}\text{of}\text{commercial}\text{hatchability}\right)=\frac{\text{Number}\text{of}\text{hatched}\text{chicks}}{\text{Number}\text{of}\text{eggs}\text{placed}\text{in}\text{the}\text{setter}}\times 100$$ (3)

Embryonic Mortality

Early embryonic deaths occurred between d 0 and 7 of incubation, while late embryonic deaths occurred between d 15 and 17. Early embryo mortality refers to those who die immediately after development, whereas late embryo mortality refers to those who are completely developed but unable to hatch.

Statistical Analysis

The acquired data were evaluated in nonequal repetitions within each group using completely randomized design (CRD). Bartlett's test was used to assess variance homogeneity. To compare the mean values, the Fisher's protected least significant difference (LSD) at the 5% probability level was used.

Spearman's correlation coefficients were used to examine the association between all of the attributes evaluated. SPSS software (IBM SPSS 23 Statistics for Mac OS, Armonk, NY) was used for all statistical analyses (Al-Shammari et al., 2019).

RESULTS

Egg Quality Traits

External and internal egg quality measurements for different colors of Japanese quail eggshells are shown in Table 2.

Table 2.

The effect of Japanese quail (Coturnix japonica) eggshell color on egg quality.

Parameters	Eggshell with color type 1	Eggshell with color type 2	Eggshell with color type 3	Eggshell with color type 4	Eggshell with color type 5
Egg weight	13.39 ± 0.14 ab	13.68 ± 0.15 a	13.24 ± 0.14 bc	13.32 ± 0.18 abc	13.00 ± 0.13 c
Egg length	35.00 ± 0.19 a	35.11 ± 0.20 a	34.10 ± 0.19 a	34.89 ± 0.22 a	34.68 ± 0.17 a
Egg width	27.15 ± 0.11 ab	27.25 ± 0.12 a	26.94 ± 0.11 ab	27.17 ± 0.15 ab	26.91 ± 0.10 b
Egg shape index	77.71 ± 0.68 a	77.75 ± 0.72 a	76.84 ± 0.68 a	77.95 ± 0.88 a	77.71 ± 0.62 a
Elongation	1.28 ± 0.86 a	1.28 ± 0.91 a	1.28 ± 0.85 a	1.28 ± 1.11 a	1.29 ± 0.78 a
Shell percentage	15.24 ± 0.31 ab	14.89 ± 0.33 b	15.16 ± 0.31 ab	15.97 ± 0.41 a	15.02 ± 0.29 ab
Albumen percentage	52.22 ± 0.60 a	52.13 ± 0.63 a	50.30 ± 0.60 bc	48.73 ± 0.78 c	50.92 ± 0.55 ab
Yolk percentage	32.52 ± 0.44 c	32.97 ± 0.47 bc	34.52 ± 0.44 a	35.29 ± 0.57 a	34.05 ± 0.40 ab

Eggshell color type 1, very dark distributed brown spots on brown egg; eggshell color type 2, small black spots on a white eggshell; eggshell color type 3, widespread brown spots on brown eggshell; eggshell color type 4, bubble egg, pin dotted on grayish brown color eggshell; and eggshell color type 5, small brown spots on very clearly white eggshell. Data = means ± standard deviation. Values with same letter in a row are not significantly (P > 0.05) different according to Fisher's protected least significant difference (LSD) test.

The eggshells of color type 2 were the heaviest (13.68 g), while those of color type 5 were the lightest (13.00 g). However, there was no statistically significant difference in the weights of eggshells of color types 1, 3, or 4 (13.39 g, 13.24 g, and 13.32 g, respectively) (Table 2). There was no statistically significant difference in egg length between different quail eggs (Table 2). Eggshells with color type 2 had the longest length (35.11 mm), while eggshells with color type 3 had the shortest (34.10 mm) (Table 2). The egg shape index and elongation did not show any significant differences among the 5 different colors (Table 2).

Only eggshells with color types 2 and 5 had a significant difference in egg width. Eggshells with color type 5 have the smallest width (26.91 mm) and eggshells with color type 2 have the largest width (27.25 mm). However, there was no significant difference between the other colors (Table 2).

Only eggshells with color types 2 and 4 had a significant difference in shell percentage (Table 2). Eggshells with color type 2 have the lowest shell percentage (14.89%) and eggshells with color type 4 have the highest shell percentage (15.97%). However, there was no difference between the other colors (Table 2). Only eggshells with color types 1, 2 and 4 had a significant difference in albumen percentage (Table 2). Eggshells with color type 1 have the higher significant albumen percentage (52.22%) and eggshells with color type 4 have the lowest albumen percentage (48.73%). However, there was no difference between the other colors (Table 2). Eggshells with color type 4 have the highest significant yolk percentage (35.295%) and eggshells with color type 1 have the lowest significant yolk percentage (32.52%) (Table 2).

The data obtained by evaluating the correlation show the relationships between measurable features of Japanese quail eggs (Table 3).

Table 3.

Relationships (Spearman's correlation coefficients) between measurable traits of Japanese quail (Coturnix japonica) eggs.

Parameters	Eggshell color	Egg weight	Egg length	Egg width	Shape index	Elongation	Yolk percentage	Shell percentage
Egg weight	−0.123*
Egg length	−0.092	0.627⁎⁎
Egg width	−0.077	0.553⁎⁎	0.384⁎⁎
Shape index	0.017	−0.210⁎⁎	−0.679⁎⁎	0.346⁎⁎
Elongation	−0.015	0.211⁎⁎	0.679⁎⁎	−0.345⁎⁎	−0.998⁎⁎
Yolk percentage	0.200⁎⁎	0.064	−0.089	0.040	0.114*	−0.109
Shell percentage	−0.012	−0.158⁎⁎	−0.196⁎⁎	−0.196⁎⁎	0.035	−0.033	0.178⁎⁎
Albumen percentage	−0.112*	−0.005	0.133*	0.018	−0.107	0.103	−0.887⁎⁎	−0.566⁎⁎

^⁎Coefficient is significant at P ≤ 0.05;

^⁎⁎coefficient is significant at P ≤ 0.01.

There was a negative phenotypic relationship between eggshell color, egg weight (−0.123 at P ≤ 0.05), and albumen percentage (−0.112 at P ≤ 0.05), but a positive significant effect on yolk percentage (0.200 at P ≤ 0.01) (Table 3). In our investigation, the egg length, width, and elongation values had extremely significant and positive associations with egg weight, with correlation values of 0.627**, 0.553**, and 0.211** for egg length and width, respectively (Table 3). In addition, egg weight has a negative and statistically significant effect on both the shape index and the shell percentage (Table 3).

Furthermore, we reported a positive relationship between egg length and egg width (0.384** at P ≤ 0.01). It also exhibited a significant effect on egg elongation (0.679** at P ≤ 0.01) (Table 3). There was also a highly negative phenotypic correlation between egg length and shape index (−0.679** at P ≤ 0.01) (Table 3). There was a negative correlation between shell percentage and egg length and egg breadth (−0.196** P ≤ 0.01) (Table 3). Egg width, on the other hand, showed a significant negative correlation with egg elongation (−0.345** at P ≤ 0.01) and a significant positive correlation with shape index (0.346** at P ≤ 0.01) (Table 3).

This study reported a strong negative phenotypic correlation (−0.998**) between egg shape index and egg elongation (Table 3).

Yolk percentage and shell percentage had a strong negative relationship with albumen percentage (−0.887**, −0.566** at P ≤ 0.01) (Table 3).

Hatching Traits

In the present study, the fertility rates, scientific hatchability, and commercial hatchability percentages of Japanese quail eggs with diverse shell colors were determined (Table 4). There were differences in fertility percentages between the different quail eggshell colors; however, there was a numerical decrease in fertility percentages in eggshells with color type 4, and color type 1 (78.33 and 89.41%), but eggshells with color type 2, color type 3, and color type 5 had very high similar values (92.01, 91.63, and 92.00%, respectively) (Table 4).

Table 4.

The effect of the eggshell color on commercial hatchability, scientific hatchability, and reproductive rates of Japanese quail (Coturnix japonica).

Eggshell color	Percentage of fertility	Percentage of scientific hatchability	Percentage of commercial hatchability
Eggshell with color type 1	89.41 ± 4.59 b	64.69 ± 4.96 c	62.03 ± 5.39 c
Eggshell with color type 2	92.01 ± 4.73 a	82.92 ± 5.11 a	76.56 ± 5.55 a
Eggshell with color type 3	91.63 ± 4.59 ab	83.93 ± 4.96 a	77.32 ± 5.39 a
Eggshell with color type 4	78.33 ± 5.99 c	68.85 ± 6.47 c	60.40 ± 7.02 c
Eggshell with color type 5	92.00 ± 4.20 a	73.54 ± 4.57 b	68.43 ± 4.97 b

Eggshell color type 1, very dark distributed brown spots on brown egg; eggshell color type 2, small black spots on a white eggshell; eggshell color type 3, widespread brown spots on brown eggshell; eggshell color type 4, bubble egg, pin dotted on grayish brown color eggshell; and eggshell color type 5, small brown spots on very clearly white eggshell. Data = means ± standard deviation. Values with same letter in a column are not significantly (P > 0.05) different according to Fisher's protected least significant difference (LSD) test.

Scientific hatchability clearly documented higher significant differences for colors, particularly eggshell with color type 3, which had the greatest value (83.93%), followed by eggshell with color type 2 (82.92%), and eggshell with color type 1 had the lowest value (64.69%) (Table 4). Furthermore, there were significant differences in commercial hatchability percentage among colored quail eggs. Eggshells with color type 3, and 2 had the highest significant commercial hatching percentages (77.32 and 76.556%, respectively) when compared to the other colors (Table 4).

Table 5 shows the Spearman's correlation coefficients between the measured characteristics of hatching Japanese quail eggs used in this investigation. A statistically significant positive relationship was identified between the percentage of fertility, and the percentage of scientific hatchability (0.292** at P ≤ 0.01), and the percentage of commercial hatchability (0.642** at P ≤ 0.01) (Table 5).

Table 5.

Relations (Spearman's correlation coefficients) between hatched measurable traits of Japanese quail (Coturnix japonica).

Parameters	Eggshell color	Percentage of fertility	Percentage of scientific hatchability
Percentage of fertility	−0.068
Percentage of scientific hatchability	0.020	0.292⁎
Percentage of commercial hatchability	−0.015	0.642⁎	0.869⁎

^⁎coefficient is significant at P ≤ 0.01.

Furthermore, the percentage of scientific hatchability was positively associated with the percentage of commercial hatchability (0.869** at P ≤ 0.01) (Table 5). The current findings revealed a very minor, nonsignificant negative correlation between eggshell color and egg fertility, as well as between it and the commercial hatchability rate (Table 5). Simultaneously, a positive, nonsignificant correlation occurred between eggshell color and scientific hatchability rate (Table 5).

Embryonic Mortality

The percentages of early and late chick mortality for Japanese quail eggs with various eggshell colors were investigated, and the results were reported to highlight the effect of different eggshell colors on these parameters (Table 6).

Table 6.

Impact of different eggshell colors of Japanese quail (Coturnix japonica) on percentages of hatched chicks, early embryonic mortality, and late embryonic mortality.

Eggshell color	Percentage of hatched chicks	Percentage of early mortality	Percentage of late mortality
Eggs with color type 1	5.52 ± 0.50 b	1.88 ± 0.27 a	0.17 ± 0.03 c
Eggs with color type 2	5.50 ± 0.58 b	0.60 ± 0.17 d	0.56 ± 0.04 a
Eggs with color type 3	6.70 ± 0.56 a	0.11 ± 0.27 b	0.00 ± 0.00 d
Eggs with color type 4	4.40 ± 0.72 c	0.85 ± 0.14 c	0.40 ± 0.07 b
Eggs with color type 5	5.60 ± 0.51 b	1.90 ± 0.23 a	0.05 ± 0.001 d

Eggshell color type 1, very dark distributed brown spots on brown egg; eggshell color type 2, small black spots on a white eggshell; eggshell color type 3, widespread brown spots on brown eggshell; eggshell color type 4, bubble egg, pin dotted on grayish brown color eggshell; and eggshell color type 5, small brown spots on very clearly white eggshell. Data = means ± standard deviation. Values with same letter in a column are not significantly (P > 0.05) different according to Fisher's protected least significant difference (LSD) test.

In hatched chicks, eggshells with color types 3, 5, 1, and 2 showed more significant variations (6.70, 5.60, 5.52, and 5.50%, respectively) than eggshells with color type 4 (4.40%), which had the lowest value (Table 6). Eggshells with color types 1 and 5 had considerably higher early mortality rates (1.88 and 1.90%, respectively), but eggshells with color types 2, 3, and 4 had significantly lower early mortality rates (0.60, 0.11, and 0.85%, respectively) (Table 6). Late mortality, on the other hand, was significantly higher in eggshells with color types 2, 4, and 1 than in eggshells with color types 3 and 5, which showed 0.00 and 0.05%, late mortality percentage respectively.

Table 7 shows the relationships (Spearman's correlation coefficients) between the embryonic mortality rate (early dead and late dead) of Japanese quail and hatched chicks. According to the current findings, the early dead embryonic rate had a negative correlation with the late dead embryonic rate (−0.361** at P ≤ 0.01) (Table 7). The effect of eggshell color had a negative, weak effect on the late dead rate and hatched chicks, as did the early dead embryonic rate and late dead embryonic rate, both of which had a negative, weak correlation with hatched chicks, with correlation values of −0.148 and −0.018, respectively (Table 7).

Table 7.

Relations (Spearman's correlation coefficients) between embryonic mortality rate (early dead and late dead) of Japanese quail (Coturnix japonica) and hatched chicks.

Parameters	Eggshell color	Early dead embryonic rate	Late dead embryonic rate
Early dead	0.070
Late dead	−0.167	−0.361⁎
Hatched chicks	−0.041	−0.148	−0.018

^⁎coefficient is significant at P ≤ 0.01.

DISCUSSION

The current study found that eggshell color had a significant impact on various external and internal quality aspects, as well as some hatching parameters in quail eggs. Egg weight, egg width, shell percentage, albumen percentage, and yolk percentage were all found to be significantly influenced by eggshell color and spot color variance (Table 2). Our findings are consistent with previous studies that found that a bird's genetic makeup might affect the quality of its eggshell as well as the egg's overall parameters (Drabik et al., 2021). Similarly, Sari et al. (2012) found that the color of the eggshell and the presence or absence of spots on the egg strongly influenced the egg quality attributes of the quail egg, including the eggshell ratio, albumen index, and yolk index.

Positive relationships were found in the current study between egg length and elongation, shape index, and egg width. The egg shape index, on the other hand, has a negative relationship with egg length (Table 3). The effect of shell color variations on eggshell structure, egg weight loss, and hatching parameters, as well as other internal and external egg quality factors, have all been the subject of previous studies (Taha, 2011; Hassan et al., 2013).

The findings from the current study revealed that the statistical impact of eggshell and spot color on egg and eggshell weight was minimal. There are a variety of factors that could be responsible for the variances; nevertheless, the ages of the birds are the most obvious (Kirikçi et al., 2005).

None of the results, however, were comparable to the previous ones, which showed that the eggshell color of pheasant eggs, whether blue, light brown, dark brown, or olive green, had no discernible effect on the egg's weight or the eggshell (Godfrey, 1947; Ahmed, 2022). While our findings were perfectly consistent with a previous study that reported significant differences in egg sizes, width, and form, the egg shape index was not significant (Choprakarn et al., 1998). There was also a disagreement with some who believed that significant differences were noticed between the different eggshell colors (Yang et al., 2009).

In the current study, eggs with a white shell expressed a shape index that was less significant compared to eggs with eggshells that were blue, olive, or brown. Our findings corroborated previous research that found a correlation between quail eggshell color and egg quality (Kirikçi et al., 2005).

Most of the research concurred with our analysis of the hatching parameters and embryonic mortality. Our findings showed that there was a highly significant association between all of the hatched parameters, including percentage of fertility, percentage of scientific hatching, and percentage of commercial hatching. It was found that the hatchability qualities of Japanese quail eggs were affected by the color of their eggshells (Gutiérrez et al., 2021). Furthermore, it was revealed that in local quail, breed differences and eggshell color had a significant influence on egg quality measures and hatchability indications (Ahmed, 2022). We found that the hatching rate of chicks from eggs with very bright shells was much lower than that of eggs with darkish shells, which was consistent with previous research on chickens (Godfrey, 1947).

Previous research has shown that the hatchability rate is lower for the brightest eggs than for the darkest eggs; furthermore, the white and spotted eggshell color displayed higher meaningful differences in early embryonic mortality rates than the blue, black, and brown splattered eggs (Soliman et al., 2000). In addition, late embryonic death rates were shown to be considerably lower for eggs with black, brown, or blue shells compared to those with speckled and white shells (Taha, 2011).

In contrast to the findings of our study, previous research found that eggs with a light brown color had the highest late death rates of any color group, whereas eggs with a violet color had the highest early mortality percentages (Soliman et al., 2000). According to Taha (2011), there were significant differences found between the 5 color groups of quail eggs in terms of the percentage of embryos that died throughout development.

CONCLUSIONS

The color of eggshells is one of the most important elements influencing consumption. Eggshell and spot color in quail eggs are also important elements influencing egg quality and hatchability, whether commercial or scientific hatchability. In addition, the color of the eggshell was found to have a significant impact on the total number of hatched chicks, as well as early and late mortality rates. A significant relationship was found between the color of the eggshell and the egg's weight, width, percentage of shell, percentage of yolk, and albumen. Based on our findings, we recommend that eggshells with color type 2 (small black spots on a white eggshell) and eggshells with color type 3 (widespread brown spots on a brown eggshell) be used for hatching procedures. This is because they have the highest fertility scientific, and commercial hatchability percentages, hatched chick, and the lowest early embryonic mortalities. In addition, eggshells with color type 3 have the lowest late embryonic mortalities. As a result, small farmers can speed up the hatching process by employing eggshell color as a significant determining feature when directing the produced eggs, whether for eating on the table or hatching. Therefore, increasing quail farming will aid in alleviating the problem with meat and eggs.