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

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1 2014 Poultry Science Association, Inc. Comparison of hatchability and some egg quality characteristics in spotted and unspotted partridge (Alectoris chukar) eggs Tamer Caglayan,* 1 Kemal Kirikci, and Ali Aygun * Department of Animal Science, Faculty of Veterinary Medicine, Kyrgyzstan-Turkey Manas University, Bishkek, Kyrgyzstan; Department of Animal Science, Faculty of Veterinary Medicine, and Department of Animal Science, Faculty of Agriculture, Selcuk University, Konya 42075, Turkey Primary Audience: Researchers, Hatchery Managers, Veterinarians, Game Bird Producers SUMMARY 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. Key words: partridge, spotted egg, hatchability, egg quality characteristic 2014 J. Appl. Poult. Res. 23 : /japr DESCRIPTION OF PROBLEM Although mostly raised as game stock and for recreational purposes, in the past decade, partridges have become one of the major alternative poultry species produced intensively. Partridges are of economic significance in many regions of the world. To ensure profitability in 1 Corresponding author: caglayan@selcuk.edu.tr

2 Caglayan et al.: COMPARISON OF HATCHABILITY 245 partridge production systems, it is required that proper hatching eggs are selected and appropriate hatching conditions are provided [1, 2]. Partridges are birds belonging to the Alectoris and Perdrix genera, which are member to the Phasinidae family. Partridge breeds, including the rock partridge (Alectoris graeca), the gray partridge (Perdix perdix), the see-see partridge (Ammoperdix griseogularis), and the chukar partridge (Alectoris chukar), are known to be found in Turkey [3]. Of these breeds, the rock and chukar partridges have been investigated most extensively [4, 5]. It has been reported that, in partridges, egg weight varies between 17 and 24 g, chick weight between 11 and 15 g, egg weight loss during hatching between 9 and 26%, and egg shape index between 74 and 77% [1, 2, 6, 7]. Furthermore, it has been indicated that, owing to different management conditions and differences in age, breed, egg weight, as well as egg-turning and storage periods, measurements of hatchability, fertility, hatchability of fertile eggs, and embryonic mortality rates vary between 43.3 to 86.4%, 50.0 to 90.08%, 80.0 to 97.33%, and 4.7 to 14.56%, respectively [2, 4, 7 9]. In a study conducted in broiler chickens, Sekeroglu and Duman [10] reported that eggshell color had effects on some egg quality characteristics and hatchability results. Many researchers have suggested that the specific gravity of partridge eggs ranges between and 1.07 and Haugh unit ranges between and [8, 11 14]. Krawczyk [15] determined the shell strength of eggs of the greenleg partridge as 2.09 to 3.07 kg. Scott and Silversides [16] and Silversides and Scott [17] indicated that, varying with breed, age, and storage periods, the albumen ph of hen eggs ranged between 7.31 and Albumen and yolk ph values of hen eggs have been reported as 9.16 and 6.27, respectively, by Ahn et al. [18]. It has been indicated that multiple factors exist that affect egg quality characteristics and hatchability results in different avian species (genetic factors, male-female proportion, egg weight, egg characteristics, age, storage period, feeding, weight of breeder animals, and so on). Eggshells with a paler background marked with darker speckles or blotches in shades of brown have protoporphyrins [19]. Protoporphyrins tend to be deposited as spots, speckles, or patches of pigment incorporated within the eggshell or superficially upon it [20]. However, very few studies exist on the effects of the eggshell structure of hatching eggs on egg quality characteristics and hatching results in partridges [9, 14, 21 23]. The current study was aimed at determining the comparison of hatchability and some egg quality characteristics in spotted and unspotted partridge (A. chukar) eggs. MATERIALS AND METHODS All bird care was approved by the institutional animal care and use committee. Breeder Flock In total, 505 eggs were obtained from chukar partridge (A. chukar; 50 wk of age) that were raised on the Research and Application Farm of Faculty of Veterinary Science, Selcuk University. An experiment was conducted using 51 chukar partridge (A. chukar) males and 102 females. The partridge were housed in battery cages (1 male:2 female; cm) with a photoperiod of 16L:8D. The partridges were fed an ad libitum diet containing 2,900 kcal of ME/kg, 24% CP, and 4% Ca (Table 1). Water was provided by automatic drinkers. Method In the present study, 445 eggs were used for hatching characteristics and 60 eggs were used for egg quality traits, for a total of 505 eggs. The eggs were visually categorized into 2 groups: spotted and unspotted. Two hundred fourteen spotted and 231 unspotted eggs were used for hatching characteristics and 30 spotted and 30 unspotted eggs were used for egg quality characteristics. The partridge eggs were collected separately on a daily basis and were classified as spotted or unspotted. The width and length of the eggs were measured with the aid of a digital caliper (accuracy 0.01 mm [24]) sensitive to 0.01 mm. The eggs were stored at 75% RH and 13 C for 14 d [7, 8, 25, 26]. All the eggs were numbered and weighed at the beginning and on d 21 of incubation to calculate moisture loss. Egg weight loss was calculated as a percentage

3 246 JAPR: Research Report Table 1. Composition of the diet Item (% unless noted) Amount Ingredient Corn, yellow Soybean meal, 45% Limesotene Dicalcium phosphate 1.50 Salt 0.35 Vitamin premix Mineral premix Vegetable oil 8.40 Total 100 Calculated value CP ME (kcal/kg) 2,900 Ca 4.00 Available P 0.43 Lys 1.37 Met + Cys 0.73 Thr 0.92 Trp Vitamin premix supplied per kilogram of diet: vitamin A, 8,800 IU; vitamin D 3, 2,200 IU; vitamin E, 13 IU; vitamin K 3, 2.67 mg; vitamin B 1, 2.5 mg; vitamin B 2, 4,67 mg; vitamin B 6, 3.33 mg; calcium d-pantothenate, 8.8 mg; nicotine acid, 44 mg; d-biotin, 0.11 mg; folic acid, 1.0 mg; vitamin B 12, 6.6 mg. 2 Mineral premix supplied per kilogram of diet: Cu, 5 mg; Fe, 60 mg; Mn, 100 mg; Zn (ZnO), 60 mg; Se, 0.15 mg; Co, 0.50 mg; coline, 125 mg. of set egg weight over the entire 0- to 21-d incubational period. After being weighed, the eggs were fumigated and placed into the incubator. The incubator was set at a temperature of 37.5 C and a 70% RH during the development period and 75% RH during the hatching period. At the end of the 21-d period the eggs were removed from the incubator, placed into tulle bags, and each group was placed into a separate hatching basket. The chicks that hatched from the eggs were weighed and chick weights were recorded, indicating their group and individual number. All unhatched eggs were broken out to distinguish unfertilized eggs from those containing dead embryos. Both the eggs and the chicks were weighed using an electronic balance sensitive to 0.01 g (accuracy 0.01 g [27]). For the evaluation of egg quality characteristics, 30 spotted and 30 unspotted eggs, laid on the same day, were used. All eggs were collected over a 24-h period. Prior to the measurement of egg quality, the eggs were stored for 1 d at room temperature (20 ± 2 C). Eggshell Color Eggshell color was measured using a Minolta Chroma Meter CR-400 [28]. The L*, a*, and b* color measurements were determined according to the CIELab color space system, where L* corresponds to dark-light chromaticity (measured on a scale of 0 to 100%, dark to light), a* to green-red chromaticity (on a scale of 60 to 60%, green to red), and b* to blue-yellow chromaticity (on a scale of 60 to 60%, blue to yellow). The instrument was calibrated with a white reference tile (L* = 97.10, a* = 4.88, b* = 7.04) before the measurements were made [29]. Eggshell color was measured at the large end of the egg. Egg Weight, Specific Gravity, Shell Strength, Albumen Height, and Haugh Unit Egg weight was measured using a balance and was recorded to the nearest 0.01 g. Specific gravity was estimated by Archimedes method [30]. Shell strength (kg) was measured with an Egg Force Reader [31]. The height of the albumen was measured using a digimatic height gage (accuracy of 0.01 mm [24]). The Haugh units were calculated from albumen height and egg weight using Haugh unit = 100 log (H W 0.37 ), where H is the albumen height (mm) and W is the weight of the egg (g) [32]. ph Measurement After the eggs were broken, the albumen was separated from the yolk. The ph of the egg albumen and yolk was measured using a ph meter with a Sentix SP electrode [33]. Yolk Color Measurements Yolk color measurements were performed using a Minolta Chroma Meter CR-400 [28]. The L*, a*, and b* color measurements were determined according to the CIELab color space system. The instrument was calibrated with a white reference tile (L* = 97.10, a* = 4.88, b* = 7.04) before the measurements were made [25]. At the end of the trial, egg weight, chick weight, egg weight loss during hatching, shape index and hatching results, and some egg qual-

4 Caglayan et al.: COMPARISON OF HATCHABILITY 247 Table 2. Mean values of egg weight, chick weight, egg weight loss during hatching, and shape index of partridge eggs Item Group n Mean ± SE P-value Egg weight (g) Spotted ± Unspotted ± 0.11 Overall ± 0.08 Chick weight (g) Spotted ± Unspotted ± 0.12 Overall ± 0.07 Egg weight loss (%) Spotted ± 0.12 <0.05 Unspotted ± 0.10 Overall ± 0.08 Shape index (%) Spotted ± Unspotted ± 0.20 Overall ± 0.16 ity characteristics were determined in the spotted and unspotted partridge eggs. Statistical Analysis The groups of spotted and unspotted eggs were compared using a t-test. Each egg was treated as a replication and the strength and amount of relationship between egg weight and chick weight were assessed by means of correlation and regression analyses, respectively. Statistical analyses were made using the SPSS 15.0 [34] software package. RESULTS AND DISCUSSION Based on the data presented in Table 2, it was determined that mean egg weight, chick weight, and shape index values were similar in the groups of spotted and unspotted eggs, whereas egg weight loss during hatching differed significantly between the 2 groups (P < 0.05). In the chukar partridges, it was ascertained that the groups of spotted and unspotted eggs significantly differed from each other for hatchability of set eggs (P < 0.001), fertility (P < 0.01), hatchability of fertile eggs (P < 0.05), and embryonic mortality (P < 0.05) rates (Table 3). Based on the data presented in Table 4, it was determined that, in the chukar partridges, statistically significant differences existed between the groups of spotted and unspotted eggs for the mean eggshell color values (P < 0.001, P < 0.01, P < 0.01 for L*, a*, and b*, respectively) and eggshell strength values (P < 0.01), whereas the specific gravity and Haugh units were found to be similar in both groups (P = 0.328). Though the mean L* (P < 0.05) and b* (P < 0.01) values of yolk color were found to be significantly lower for spotted eggs, no statistically signifi- Table 3. Rates of hatchability, fertility, and embryonic mortality in partridge eggs Item Group n Mean ± SE P-value Fertility (%) Spotted ± 0.47 <0.01 Unspotted ± 0.53 Overall ± 3.02 Hatchability (%) Spotted ± 1.40 <0.001 Unspotted ± 0.59 Overall ± 4.59 Hatchability of fertile eggs (%) Spotted ± 1.12 <0.05 Unspotted ± 0.21 Overall ± 2.44 Embryonic mortality of fertile eggs (%) Spotted ± 1.12 <0.05 Unspotted ± 0.21 Overall ± 2.44

5 248 JAPR: Research Report Table 4. Some egg quality characteristics of partridge eggs Item 1 Group n Mean ± SE P-value Eggshell color L* Spotted ± 0.58 <0.001 Unspotted ± 0.49 Overall ± 0.42 Eggshell color a* Spotted ± 0.25 <0.01 Unspotted ± 0.25 Overall ± 0.19 Eggshell color b* Spotted ± 0.38 <0.01 Unspotted ± 0.54 Overall ± 0.35 Specific gravity Spotted ± Unspotted ± Overall ± 0.00 Eggshell strength (kg) Spotted ± 0.06 <0.01 Unspotted ± 0.11 Overall ± 0.07 Albumen height (mm) Spotted ± Unspotted ± 0.11 Overall ± 0.08 Haugh unit Spotted ± Unspotted ± 0.78 Overall ± 0.61 Yolk color L* Spotted ± 0.13 <0.05 Unspotted ± 0.17 Overall ± 0.11 Yolk color a* Spotted ± Unspotted ± 0.06 Overall ± 0.06 Yolk color b* Spotted ± 0.16 <0.01 Unspotted ± 0.20 Overall ± 0.14 Albumen ph Spotted ± Unspotted ± 0.02 Overall ± 0.01 Yolk ph Spotted ± Unspotted ± 0.00 Overall ± L* = light-dark chromaticity; a* = green-red chromaticity; b* = blue-yellow chromaticity. cant difference was found between the spotted and unspotted eggs for the yolk color a* (P = 0.836), albumen ph (P = 0.792), and yolk ph values (P = 0.060; Table 4). Chick and egg weight were highly correlated with each other (r = 0.956; P < 0.001). The regression equation between egg and chick weight was determined by Chick weight = egg weight (R 2 = 91.4%; P < 0.001). The egg weight values were determined to be and g for the spotted and unspotted eggs, respectively, in the present study, similar to the values (20.70 g) reported by Cufadar et al. [35] for chukar partridges. Furthermore, egg weight values previously reported for the chukar partridge (21.40 [1] and g [36]) are higher than the egg weight values determined in the present study. The chick weight reported by Cetin et al. [4], g, for the chukar partridge is similar to the chick weight determined in this study, g. The chick weight (14.07 g) in the spotted group in the present study is similar to the values previously reported for the rock partridge by Kirikci et al. [5] (14.22 g). The shape index determined for the spotted and unspotted groups in the present study (77.79 and 78.31%, respectively) are higher than the values reported by Alkan et al. [1] for the chukar partridge (74.00%) and by Hashemipour et al. [14] for chukar partridges given probiotics (75.38%),

6 Caglayan et al.: COMPARISON OF HATCHABILITY 249 and are similar to the values reported by Song et al. [37] for the chukar partrdige (77.30%). In the present study, egg weight loss during hatching was 9.32 and 9.70% for the spotted and unspotted groups, respectively (P < 0.05). The mean egg weight loss of 15.48% for the eggs of the rock partridge by Caglayan et al. [2] is higher than the values determined in the present study (9.32 and 9.70%). In research conducted on Ross 308 broiler breeders, Sekeroglu and Duman [10] detected that egg weight loss during hatching was greater in eggs with light eggshell color. The fertility rates determined in the current study are similar to those reported by Cufadar et al. [35] for chukar partridge eggs (87.57%) and by Cetin et al. [4] for the hatching eggs of chukar partridges raised in flocks (89.06%). The hatchability of set eggs determined for the spotted group (78.97%) was found to be similar to the values reported by Cetin et al. [4] for the hatching eggs of chukar partridges raised under different management conditions (81.25%). The rates of hatchability of fertile eggs determined in our study are in agreement with those indicated in previous reports ( % [4]; 85.44% [2]; % [8]; % [7]). Embryonic mortality rates in the spotted and unspotted groups were and 18.89%, respectively (P < 0.05). Similarly, in research conducted in light and dark colored eggs laid by hens of the Barred Rock 1 genotype [38], it was ascertained that the fertility rate was lower and the embryonic mortality rate was higher in light colored eggs (P < 0.05). In another study on Ross 308 broiler breeders [10], it was determined that the hatchability results of dark colored eggs were better. Eggshell color values in the spotted and unspotted groups were determined as and (P < 0.001), 4.06 and 2.84 (P < 0.01), and (P < 0.01) for L*, a*, and b* respectively. Aygun [39] stated that the shell L* value might be used to express whether the color of the eggshell was dark or light and could be considered as a discriminative color criterion: the more the shell L* value decreases, the more the egg shell color is darker. In the present study, it was demonstrated that the L* value was higher in the unspotted group (P < 0.001), and that a* and b* values were higher in the spotted group (P < 0.01). Roberts [40] reported eggshell color as one of the factors influential on the shell quality of hen eggs. The egg specific gravity value determined in the present study was observed to be higher than that reported for the chukar partridge by Hashamipour et al. [14] (1.05). The shell strength values (2.92 and 2.93 kg) reported by Castille et al. [41] for the eggs of red-legged partridges (Alectoris rufa) raised in 2 different regions of Spain were found to be rather high compared with the values determined in the present study. Furthermore, Krawczyk [15] reported the shell strength of eggs laid by free-range greenleg partridges to be 2.70 kg, which was also higher than the results obtained in the present study and indicated the correlation between shell thickness and shell strength as (P < 0.05). In their investigation on the effect of age on egg quality characteristics in hybrid chickens, Akbas et al. [42] reported the correlation between shell strength and age as and mean shell strength as 2.96 kg, the latter being in agreement with the values determined for the spotted and unspotted groups in the present study. The albumen height was determined as 3.87 and 4.04 mm in the spotted and unspotted groups, respectively (P = 0.328). Zhang [43] reported no significant correlation between egg shell color and albumen height in brown layer eggs. In the present study, yolk color in the spotted and unspotted groups was determined as and (P < 0.05), 3.97 and 3.95 (P = 0.836), and and (P < 0.01) for L*, a*, and b*, respectively. Aygun [44] reported the correlation of shell L* with yolk L* was positive (r = 0.198, P < 0.001). These results indicate that eggs lighter shells had lighter of yolk color. Yolk color was reported as 9.53 (Roch score) by Ahn et al. [18] for the eggs of 79-wk-old White Leghorn hens and 8.00 (Roch score) by Hashemipour et al. [14] for the eggs of chukar partridges. Furthermore, Krawczyk [15] reported the yolk color of eggs laid by organically raised greenleg partridges as Values higher than those determined for the spotted and unspotted groups in the present study were reported by Mourao et al. [45] for the eggs of 44-wk-old ISA Brown hens, and yolk color values for the group not given alfalfa were indicated as , 3.117, and for L*, a*, and b*, respectively. Furthermore, the L*, a*, b*

7 250 JAPR: Research Report values reported by Abudabos [46] for the eggs of Hy-Line hens were 56.5, 0.87, and 46.5, respectively. Albumen and yolk ph values in the spotted and unspotted groups were found to be in agreement with those reported by Ahn et al. [18] for the eggs of 79-wk-old White Leghorn hens (9.16 and 6.27 for albumen and yolk ph, respectively). The albumen ph values reported by Scott and Silversides [16] and Silversides and Scott [17] were 7.31 to 7.43 and 7.37 to 7.43 for eggs laid by ISA Brown and ISA White hens, respectively, lower than those determined in the present study. Furthermore, Roberts [40] reported that as the storage period of hen eggs increased, the albumen ph value increased. In the present study, a high correlation (r = 0.956) and regression (R 2 = 91.4%) was determined to exist between egg and chick weight (P < 0.001). These findings were observed to be in agreement with literature reports [2, 47 49]. Our observation indicates that the same birds might not always produce the same type of eggs, similar to the findings of Krist and Grim [50]. In the current study, spotted eggs had a lower egg weight loss and embryonic mortality, as well as a greater fertility, hatchability, and egg shell strength than unspotted eggs. Gosler et al. [51] reported similar results and highlighted that protoporphyrin pigments (causing spots) might play role in the strengthening of eggshell, but decreasing eggshell permeability. It is reported that increases in eggshell permeability resulted in increased embryonic mortality and decreased hatchability [52 54]. CONCLUSIONS AND APPLICATIONS 1. In chukar partridges (A. chukar), spots on hatching eggs affected some internal and external egg quality characteristics and hatchability results. 2. It may be suggested that spotted eggs are more suitable for use as hatching eggs. 3. 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