SUMMARY
Article Details: Received: 2020-09-25 | Accepted: 2020-11-27 | Available online: 2021-01-31https://doi.org/10.15414/afz.2021.24.mi-prap.11-14AbstractThe objective of this study was to compare some internal and external quality parameters of eggs during laying period at 7, 8 and 13 months of hen´s age.Hens of genetic animal resources of the Oravka breed from NAFC-RIAP Nitra were included in experiment. In our experiment the average egg weight was significantly increased with the age of the laying hens (P<0.0001, P=0.0076). There were significant differences in egg length and egg width, but no significant differences in egg shape index. The thickness of eggshell was demonstrably thinner in all measured positions of the egg with increasing age of laying hens. The average eggshell thickness decreased from 429.30 ± 1.25 µm to 420.98 ± 1.30 µm (P<0.0001) during the laying The albumen weight during laying varied from 31.29±0.36 g to 33.22±0.35 g. Albumen height and Haugh Unit measure the viscosity of the thick albumen. The Haugh Unit in Oravka breed were lower in the oldest hens(69.17±1.36). All yolk characteristics increased with age. The yolk weight increased from 14.64±0.21 g at the age of 7 months to 19.67±0.27 g at the age of 13 months (P<0.0001).We found significant differences in yolk colour only between hens of 8 and 13 months age (P=0.0021). Keywords: egg, external quality, internal quality, eggshell, Oravka hens, ageReferencesAdeougun, I. O., Amole, F. O. (2004). Some quality parameters of exotic chicken eggs under different storageconditions.Bulletin of Animal Health and Production in Africa, 52, 43–47.Cath, A.U. et al. (2012). Performance and egg quality of aged laying hens fed diets supplemented with meat and bone meal or oyster shell meal. South African Journal of Animal Science,42(1), 75–82. 10.4314/sajas.v42i1.9Dudosola, I. O. (2010). Comparative evaluation of internal and external qualities of eggs from quail and guinea fowl. International Research Journal of Plant Science, 1(5), 112–115.Fletscher, D. L. et al. (1981). The influence of layer flock age on egg component yields and solids content. Poultry Science, 60(5), 983–987. https://doi.org/10.3382/ps.0600983Fletscher D. L. et al. (1983). The relationship of layer flock age and egg weight on egg component yields and solids content. Poultry Science, 62(9), 1800–1805.Hanusová, E. et al. (2015).Effect of breed on some parameters of egg quality in laying hens. Acta fytotechnica et zootechnica, 18(1), 20–24. DOI:10.15414/afz.2015.18.01.20–24Hrncár, C. et al. (2016). Comparative analysis of the external and internal egg quality in different pure chicken breeds. Acta fytotechnica et zootechnica, 19, Special Issue, 123-127. http://dx.doi.org/10.15414/afz.2016.19.si.123-127Islam, M. S., Dutta, D. R. K.(2010). Egg quality traits of indigenous. exotic and crossbred chickens (Gallus domesticus L.)in Rajshahi. Bangladesh. Journal of Life Earth Science, 5:63–67. 10.3329/jles.v5i0.7352Johnston, S. A., Gous, R. M. (2003). An improved mathematical model of the ovulatory cycle of the laying hen. British Poultry Science, 44:752–760. https://doi.org/10.1080/00071660310001643723Kocevski, D. et al. (2011). The influence of strain and age on some egg quality parameters of commercial laying hens.Biotechnology in Animal Husbandry, 27(4), 1649–1658. 10.2298/BAH1104649KRoberts, J.R. (2010). Factors affecting egg shell and internal egg quality. Journal of Poultry Science, 3, 161–177. DOI:http://dx.doi.org/10.2141/jpsa.41.161SAS Institute (2009). SAS® Users Guide: Statistics, Version 9.2 SAS Institute Inc., Cary, N.C.Savegnago, R. P. et al. (2011). Estimates of genetic parameters and cluster and principal components analyses of breeding values related to egg production traits in a White Leghorn population.Poultry Science,90, 2174–2188. https://doi.org/10.3382/ps.2011-01474Scott, T. A., Silversides, F. G. (2001). Effect of storage and layer age on quality of eggs from two lines of hens. PoultryScience, 80(8), 1245–1248. 10.1093/ps/80.8.1240Stadelman, W. J. (1977).Quality identification of shell eggs in egg science and technology. 2nd ed. Westport, Connecticut: AVIPublishing Company Inc., pp. 33.Tumová, E., Gous, R. M. (2012). Interaction between oviposition time, age and environmental temperature and egg quality traits in laying hens and broiler breeders. Czech Journal of Animal Science, 57(12), 541–549. 10.17221/6411-CJASVan Den Brand, H. et al. (2004). Effects of housing system (outdoor vs. cages) and age of laying hens on egg characteristics. British Poultry Science, 45, 745–752. Doi: 10.1080/00071660400014283Washburn, K. W. (1990). Genetic variation in egg composition. In R. D. Crawford, ed. Poultry Breeding and Genetics. New York: Elsevier Scientific Publishers, pp. 781–798. https://doi.org/10.3382/ps.0580529