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The effect of oviposition on egg quality at the beginning and end of the laying cycle
Greglová, Ellen ; Tůmová, Eva (advisor) ; Michaela, Michaela (referee)
The egg quality is affected by many factors, among which various interactions may occur. The aim of the diploma thesis was to assess changes in the quality of eggs laid in the morning, midday, and in the evening at the beginning and the end of the laying cycle in six laying hybrids: Bovans Brown, Bovans Sperwer, Isa Sussex, Moravia Barred, Moravia BSL and Dekalb White, each individually housed in cages. The experiment was realized at the beginning of lay, between 19 and 26 weeks of age and at the end of lay betwen 64 and 70 weeks of age. During the experiment, were conected eggs at 6 a.m., 9 a.m., 12 p.m. and 5 p.m. and were recorded daily. In total, 300 eggs from each genotype and of each period were evaluated. At the beginning of the laying cycle, the interactions of oviposition time and genotype (P 0.03), were observed in the yolk weight (P 0.004) and the color of the yolk. The highest weight yolk had the eggs laid by white-egg hybrid Dekalb White early in the morning (13.79 g at 6 a.m.) and during the day the weight of yolk decreased. However, the yolk weight of brown-egg Bovan Brown hens increased until 9 a.m. and then decreased again. The darkest yolk was laid by genotype Bovans Brown at 12 p.m. (8.0 g), while the lightest yolk was laid by Dekalb White at 12 p. m. (3.00). At the end of the laying cycle, interactions of oviposition time and genotype (P 0.028) were observed in the albumen percentage. The highest values had hybrid Moravia BSL with eggs laid in 12 a.m., 5 p.m. 64.23 %, 63.33 %), and the lowest percentage had hens of Bovans Sperwer at 9 a.m. (58.19 %). Oviposition time significantly (P 0.003) affected only the strength of the shell. At the beginning of the laying cycle, we recorded higher strength at 9.00 a.m. (54.89 g.cm-2) compared to the eggs collected at 6 a.m. and later (41.39 a 24.58 g.cm-2). The genotype (P 0.005) affected most of the parameters of quality.
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