ISSN: 2320-5407 Int. J. Adv. Res. 4(9), 1397-1404 Journal Homepage: -www.journalijar.com Article DOI: Article DOI:10.21474/IJAR01/1740 DOI URL: http://dx.doi.org/10.21474/IJAR01/1740 RESEARCH ARTICLE External and internal characteristics of ostrich eggs from Dibete Ostrich farm. John Cassius Moreki, Gadzikanani Kgosana Majuta and James Buti Machete. Department of Animal Science and Production, Botswana University of Agriculture and Natural Resources, Private Bag 0027, Gaborone, Botswana. …………………………………………………………………………………………………….... Manuscript Info Abstract ……………………. ……………………………………………………………… Manuscript History Received: 12 July 2016 Final Accepted: 22 August 2016 Published: September 2016 Key words:Egg quality, external traits, Haugh unit, internal traits, ostrich. A total of 39 ostrich eggs from three different flocks (A, B and C) were obtained from Dibete Ostrich Multiplication Unit (DOMU) and used to assess the internal and external egg quality characteristics. The experiment was conducted at Botswana University of Agriculture and Natural Resources (BUAN). Eggs were individually weighed prior to opening in the Meat Science Laboratory at BUAN using a saw in order to remove the internal contents. Parameters studied include egg weight, shell thickness, shell weight, shell percentage, egg contents weight, egg shape index, egg surface area, SWUSA, albumen ratio, shell ratio, yolk ratio, yolk index, shell volume, shell density, egg volume, egg specific gravity. Results showed that only the Haugh unit was significantly (p<.0001) different among the flocks while other parameters were not significantly (p>0.05) different from each other. Egg weight was highly and positively correlated with egg contents weight, egg surface area, albumen ratio and egg volume (r=0.97884, 0.99958, 0.60295 and 0.98344, respectively; p<.0001, <.0001, <.0001 and<.0001, respectively) but highly and negatively correlated with yolk ratio (r=0.60498; p=0.0001) and weakly and positively correlated with shell weight, Haugh unit and shell volume (r= 0.4648; p=0.0029, 0.36348; p=0.0229, and 0.45506; p=0.0036, respectively). Shell thickness was positively and significantly correlated with shell weight, shell percentage, SWUSA, shell ratio and shell density (r=0.48506, 0.51737, 0.53380, 0.51737, 0.50416, respectively; P=0.0017, 0.0007, 0.0005, 0.0007, 0.0011, respectively). Egg specific gravity was positively and significantly (r=0.43329; p=0.0059) correlated with shell volume. Ostriches of different ages should be reared separately though there is very little variation in quality traits. Copy Right, IJAR, 2016,. All rights reserved. …………………………………………………………………………………………………….... Introduction:Ostrich eggs are the largest eggs produced by a living bird measuring 15.24 cm in length and 12.7 cm in diameter (Cooper, 2001). The weight of an ostrich eggranges from 1.0 to 2.0 kg (Pleti et al., 2009).According to Cooper et al.(2009), ostrich egg shell thickness ranges from 1.6 to 2.2 mm.Extremely strong shells of ostrich eggs make them very resistant to breakage during handling and transportation while also serving as a basis for the making of curios Corresponding Author:-John Cassius Moreki Address:-Department of Animal Science and Production, Botswana University of Agriculture and Natural Resources, Private Bag 0027, Gaborone, Botswana. 1397 ISSN: 2320-5407 Int. J. Adv. Res. 4(9), 1397-1404 (Mushi et al., 2007). In a 1500 g ostrich egg,the mean weight of albumen, yolk and shell are 900 g, 317 g and 296 g, respectively. For a long time ostrich eggs have been consumed by humans and their shells used as containers and/or also made into beads. Egg quality is defined as the characteristics of an egg that affect its acceptability to the consumers. Hence, egg quality is the more important price contributing factor in both table and hatching eggs, therefore the economic success of a laying flock solely depends on the total number of quality eggs produced (Monira et al., 2003). Ostrich eggs may vary from white to yellowish white. The egg is pitted with superficial pores of various shapes and sizes (Monira et al., 2003). Christensen et al. (1996) found the distribution of pores per square centimetre to be 20.2±2.0, 18.3±1.6 and 17.7±1.1 in the broad end, equator and sharp end, respectively. The weight and proportion of egg represented by albumen, yolk and shell vary significantly between the strains of birds. Shell thickness is significantly influenced by bird strain; also higher egg size may also influence shell quality (Monira et al., 2003). Recent interest in ostrich farming has increased the demand for information about ratites and ratite management in a commercial environment (Miljković et al., 2009). However, basic information required to develop this industry is unavailable. While the chicken egg has been extensively studied for its internal and external qualities, as well as, for its composition, such information is not so well documented in other poultry species such as ostrich (Alkan et al., 2015). Therefore, the aim of the study was to evaluate the ostrich egg quality characteristics. Materials and Methods:Study area:The experiment was conducted at Botswana University of Agriculture and Natural Resources (BUAN), Content farm, Sebele, which is located 10 km north of Gaborone, capital city of Botswana. Experimental design:A total of 40 eggs were purchased at a government ostrich facility, Dibete Ostrich Multiplication Unit (DOMU), situated about 100 km north of Gaborone along the A1 highway. Eggs were weighed using an electronic scale, whereas length and width of individual eggs were measured using Vernier calipers (Benoît et al., 2014). Thereafter, eggs were opened using a saw in the Meat Science Laboratory at BUAN in order to remove the internal contents. The yolk and albumen were separated by pouring the internal contents of the egg on a flat surface and collecting the yolk enclosed by vitellinemembrane into a container. An empty container was weighed and used to weigh the yolk by collecting it into a container and thereafter weighing the container with the yolk. The weight of the yolk was obtained by subtracting the weight of the container from the weight of the container and yolk. Internal parameters measured were yolk weight, yolk height, yolk width, albumen height, albumen weight, shell thickness and shell weight. An electronic scale sensitive to 0.01 was used to measure the weight of albumen, yolk and shell while Vernier calipers were used to measure the height and width of albumen and yolk. Shell thickness was measured using micrometer screw gauge, whereas albumen weight was calculated by subtracting yolk weight and shell weight from egg weight. After collection of these data, quality traits such as shell ratio, yolk ratio, albumen ratio, Haugh unit, egg surface area (ESA), shell percentage, shell volume, shell density, shell weight/surface area (SWUSA), egg specific gravity (ESG), egg volume, weight of egg contents and egg shape index (ESI) were evaluated according to El-Safty and Mahrose (2009) and Alkan et al. (2015) using the formulae below. Egg volume = 0.51*egg length*egg breath² Egg surface area=39782W0.7056 where W is egg weight Haugh unit = 100 log (H - 1.7W0.37 + 7.6), where H is albumen height and W is egg weight Egg surface area(cm²) Shell volume = Egg length (cm) Shell density = Shell weight Shell volume 1398 ISSN: 2320-5407 Shell percentage = Int. J. Adv. Res. 4(9), 1397-1404 Shell weight ∗ 100 Egg weight Egg specific gravity (g/cm²) = Egg shape index = Shell ratio (%) = Egg width ∗ 100 Egg length Shell weight ∗ 100 Egg weight Albumen ratio (%) = Yolk ratio (%) = Albumen weight ∗ 100 Egg weight Yolk weight ∗ 100 Egg weight Yolk weight Yolk index = Yolk Egg weight Egg volume diameter ∗ 100. Statistical analysis:Data were analyzed using Statistical Analysis System (SAS) software (version 9.2) (SAS Institute System, 2008). The proccorrprocedure of SAS was used to calculate correlation coefficients. Significant differences among the means were tested by Duncan's Multiple Range Test. Results and Discussion:External and internal quality traits of ostrich eggs:All external and internal physical quality traits except Haugh unit were not significantly (P>.05) different from each other (Table 1). The average egg weight for flocks A, B and C was 1.27 kg, 1.26 kg and 1.34 kg, respectively. The result on egg weight in this study is consistent with Mushi et al. (2007) and Brand et al. (2003) who found average weight of an ostrich egg to be 1321 g and 1455 g, respectively. Previous study of Benoît et al. (2014) reported average egg weight of 1370 g and 1200 g during the rainy and dry seasons, respectively. On average albumen, shell and yolk in the current study were 60.5%, 13.36%, 26.04%, respectively. Koutinhouin et al. (2014) reported that the albumen, yolk and shell make up 57.1-59.4%, 21-23.3% and 19.6% of the egg, respectively. Selvan et al.(2014) found albumen, yolk and egg shell percentage to be 57.51 (825.35 g), 27.64 (396.76 g) and 14.83 (212.89 g), respectively. In the study of Di Meo et al. (2003) albumen, yolk and shell amounted to 57.1, 23.3 and 19.6%, respectively. El-safty (2015) reported slightly higher values of egg albumen, yolk and shell compared to the current results. Average yolk index reported in the current study was 32.9% which is consistent with El-Safty and Mahrose (2009) who found a value of 30.4%. However, a higher yolk index (44%) was reported by Al-Obaidi et al. (2012). The average shape index (82.65%) in the current study is consistent withHorbańczuk et al. (2003), Nedomová and Buchar (2013), Benoît et al. (2014)andSelvan et al.(2014)who obtained shape indices of 83%, 82.49%, 83.5-83.86% and 82.86%, respectively. Similarly, Elsayed(2009) and Koutinhouin et al. (2014) found shape index values of ostrich eggs to be 80% and 83.5%, respectively. In this study, average egg specific gravity was 1.15897 g/cm3. Similarly, Al-Obaidi et al. (2012) reported a value of1.15 g/cm3 while Koutinhouin et al. (2014) reported a specific gravity of 1.13 g/cm3 during the rainy season and 1.03 g/cm3 in the dry season. The authorsfound average egg shell thickness values of ostrich eggs to be 2.2 to 2.24 mm in the equatorial regions which is slightly higher than 1.87 mm recorded in this study. Similarly, Mushi et al. (2007) reported shell thickness of 1.65 mm which is slightly lower than the value obtained in the current study. The study by Cooper et al. (2009)found that shell thickness of ostrich egg ranges from 1.6 to 2.2 mm. Similarly, Selvan et al.(2014) reported shell thickness of 1.92 to 2.4 mm, whereas Di Meo et al. (2003) found that average shell thickness ranged from 2.20 mm at the equator to 2.24 mm at the sharp end. 1399 ISSN: 2320-5407 Int. J. Adv. Res. 4(9), 1397-1404 Table 1: Means ± SE of external and internal physical quality traits of ostrich eggs Flocks Parameter A B Egg weight( kg) 1.2758 ± 0.041 1.2636 ± 1.264 Haugh unit 129.05 ±0.833 127.33 ± 0.771 Shell thickness, (mm) 1.8658 ± 0.069 1.9207± 0.0640 Shell weight (kg) 0.1750 ± 0.009 0.1707 ± 0.008 Shell percentage (%) 13.8325± 0.574 13.4500± 0.531 Egg contents weight( kg) Egg shape index (%) 1.0992 ± 0.037 83.1183± 0.784 1.0929 ± 0.035 81.8550 ±0.726 Egg surface area (m2) Shell weight/unit surface area, (mg/cm2) Albumen ratio (%) 4.7158 ± 0.107 37.2617± 1.566 4.6871 ±0.099 36.2107 ±1.449 60.3275± 1.205 59.5950 ±1.116 Shell ratio (%) 13.8325± 0.574 13.4500 ±0.531 Yolk ratio (%) 25.8392± 1.064 26.9543 ±0.985 Yolk index Shell volume (cm3) 0.3217 ±0.0103 0.03000±0.0004 0.3379 ±0.009 0.03000 ± 0.0004 Shell density (g/cm3) 5.4358 ± 0.249 5.3386 ±0.230 Egg volume (cm3) 1102.85 ± 34.678 1088.01 ± 32.106 Egg specific gravity (gm/cm3) 1.1567 ± 0.007 1.1621 ± 0.006 NS: Non-significant; ***:p<0.001; ANOVA: Analysis of variance; SE: Standard error C 1.3408 ± 0.040 137.23 ± 0.800 1.8200 ± 0.066 0.1715 ± 0.009 12.8477± 0.551 1.1692 ± 0.036 83.0762± 0.752 4.8877 ± 0.103 35.1115± 1.505 61.9038± 1.157 12.8477± 0.551 25.2485± 1.021 0.3277 ± 0.010 0.03077± 0.0004 5.2200 ± 0.239 1157.51± 33.318 1.1577 ± 0.007 ANOVA NS *** NS NS NS NS NS NS NS NS NS NS NS NS NS NS NS The average Haugh unit in the present study was 131.16. According to Pleti et al. (2009), Haugh unit>100 shows very good egg quality. Rath et al. (2015) stated that the higher the yolk index and the Haugh unit, the more desirable the egg quality which implies that Haugh unit and yolk index are indicators of internal egg quality. The Haugh unit varies greatly between the flocks which might imply differences in internal egg quality. The variation in Haugh unit values in the present study might be due to variation in the age of the birds and the differences in storage time of the eggs. Correlations of egg physical characteristics:Table 2 shows the correlations between ostrich egg quality traits.Egg weight was highly and positively correlated with egg contents weight, ESA, albumen ratio and egg volume (r= 0.97884, 0.99958, 0.60295 and 0.98344, respectively) but highly and negatively correlated with yolk ratio (r= -0.60498) and weakly and positively correlated with shell weight, Haugh unit and shell volume(r= 0.4648, 0.36348 and 0.45506, respectively). Selvan et al.(2014) reported a significant correlation between albumen and yolk percentage with egg weight, but with a negative relationship for yolk and positive for albumen. Alkan et al. (2015) reported a positive correlation between egg weight and shell thickness which is similar to what was found in the current study (Table 2). In disagreement with the present results, Benoît et al. (2014) found a nonsignificant correlation between shell thickness and egg weight of red-necked ostrich. For Monira et al. (2003), shell thickness is significantly influenced by bird strain which might be a reason for non-significant correlation in this study. According to Bobbo et al. (2013), egg weight has an indirect relationship with shell quality; however, egg shell thickness has positive significant correlation with shell weight. 1400 ISSN: 2320-5407 Int. J. Adv. Res. 4(9), 1397-1404 Shell thickness was positively and significantly correlated with shell weight, shell percentage, SWUSA, shell ratio and shell density (r=0.48506, 0.51737, 0.53380, 0.51737, 0.50416 respectively; P= 0.0017, 0.0007, 0.0005, 0.0007, 0.0011, respectively). These results are consistent with El-Safty and Mahrose (2009) and Koutinhouin et al. (2014) who reported similar correlations. However, Bobbo et al. (2013) reported a negative correlation between shell thickness and shell weight for smooth feathered ostriches and frizzle but a strong positive correlation for naked neck. Shell weight was positively and strongly correlated with shell percentage and shell density. These results are in line with those reported by El-Safty and Mahrose (2009). The Haugh unit was weakly and positively correlated with egg contents weight, ESA and egg volume (r= 0.40106, 0.36434 and 0.39206, respectively), whereas albumen ratio was negatively and significantly correlated with shell ratio, yolk ratio and yolk index (r= -0.48390, -0.88121, -0.57168 and p= 0.0018, 0.0001, 0.0001, respectively) (Table 2). El-Safty and Mahrose (2009) reported similar correlations in African black neck ostrich. According to Kontecka et al. (2012), an increase in the yolk weight results in a decrease in the percentage of albumen. Egg specific gravity (ESG) was positively and significantly (r=0.43329; p=0.0059) correlated with shell volume. The current result indicates that an increase in shell volume increases ESG. This result is in line with Gryzinska and Batkowska (2014) who stated that as ESG declines the number of cracks generally increase; hence ESG indicates the quantity of shell relative to other components of the egg. The ESG usually declines over time partly due to the size of the egg increasing more rapidly than shell weight (Butcher and Miles, 2015). Therefore, the differences in ESG values among eggs of similar weights are mainly due to variations in the amount of shell. 1401 ISSN: 2320-5407 Int. J. Adv. Res. 4(9), 1397-1404 Table 2: Correlations between egg physical characteristics of Ostrich at Dibete Ostrich Multiplication Unit Traits Egg weight Egg weig ht - Shell thickne ss 0.03432 Shell weight Shell percent Haugh unit 0.36348 Egg contents weight 0.97884* Egg surface area 0.99958* 0.4648* -0.147 * ** ** SWUSA 0.06446ns Album en ratio 0.6029 5*** Shell ratio Yolk ratio Yolk index Shell volume Shell density Egg volume -0.15475 0.60498** 0.04200 0.45506* 0.30429 0.98344* ** * Shell thickne ss Shell weight Shell percent - 0.4850 6* 0.51737* 0.14840 -0.07268 0.03941 0.53380*** - 0.79421* 0.01014 0.26434 0.27623 0.46856* 0.90741*** - 0.40106* 0.36434* -0.18652 - 0.97792* -0.13814 ** ** - 0.34991* 0.15081n 0.97517*** s Haugh unit Egg content s weight Egg surface area SWUS A Albume n ratio Shell ratio Y0lk ratio * ** 0.2486 7 0.0708 0.4839 0** 0.1205 9 0.6679 1*** 0.51737* 0.00475 0.15610 -0.04181 0.50416* 0.00527 0.79421* -0.34787* -0.01611 -0.01252 0.97258* 0.46756* ** ** 1.00000* ** ** 0.01273* -0.07546 -0.26575 ** 0.87783* -0.14954 ** -0.26434 0.00511 0.24824 0.19098 -0.11052 0.39206* 0.34991* 0.57380** 0.05373 0.50257* 0.10773 0.95993* ** * ** * - 0.06882 0.5978 7*** -0.15081 0.60131** 0.04974 0.44354* 0.30989* 0.98421* ** * - 0.3593 3* - 0.97517* -0.11612 -0.05680 -0.19463 ** 0.95712* 0.06919 ** 0.48390* 0.88121** 0.57168* * * ** - 0.01273 0.07546 0.69419* - 0.32027* -0.18046 0.57412* -0.26575 0.87783* -0.14954 ** ** -0.22195 -0.26791 ** 0.57489* ** Yolk index Shell volume Shell density Egg volume - 0.00239 -0.04324 0.06166 - -0.10700 0.37412* - 0..31671 * - * p≤0.05; ** p≤0.01; ***p≤0.001 SWUSA = Shell weight per unit surface area 1402 ISSN: 2320-5407 Int. J. Adv. Res. 4(9), 1397-1404 Conclusions:Internal and external quality traits were not significantly different across the flocks except the Haugh unit. Egg weight wassignificantlycorrelated with most other quality traits showing a relationship between the traits. The current results suggest that ostriches of different ages should be reared separately although there is very little variation in quality traits. Acknowledgements:The authors wish to thank Department of Animal Production for supplying eggs used in this study and Dr. K. Tshireletsoforhelp with statistical analysis. References:1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. Alkan, S, Galiç, A., Karsli,T.andKarabağ, K.(2015): Effects of egg weight on egg quality traits in partridge (AlectorisChukar). J. Appl. Anim. Res., 43(4): 450-456. Al-Obaidi, F.A., Al-Shadeedi, Sh.M. andMousa, A.S.(2012): Egg morphology, quality and chemical characteristics of ostrich (Struthiocameluscamelus). Al-Anbar J. 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