Effects of cage type on performance, welfare, and microbiological properties of laying hens during the molting period and the second production cycle.

As most of the unenriched cages will soon switch to enriched cages, it is important to characterize all the effects in the laying hens for sustainable production. Laying hens can be used in several production periods by applying molting. The aim of this study was to determine the cage type (unenriched and enriched) on performance, welfare, and microbiological properties of laying hens during the molting period and the second production cycle. Overall, 840 brown laying hybrids were used in the experiment. Laying hens were reared on two different cage types (unenriched cage (UEC) and enriched cage (EC)) in the same poultry house. When the hybrids were 75 weeks old, they were subjected to force molting with whole grain barley. Performance, welfare, microbiological, and serological data of laying hens were obtained from 73 to 107 weeks of age. Egg production, egg weight, feed conversion ratio, breaking strength, albumen and yolk index, Haugh unit, feather condition, and breaking force of femur and metatarsus were better in the post-molting period. However, keel bone deformities and Newcastle disease virus antibody titers are the worst in the post-molting period. Stiffness of femur and metatarsus was increased with period. These results indicate that necessary precautions should be taken against the problems that may occur in the direction of bone and health. During the molting period, hens kept in EC had lower egg production but they returned to egg production at a high rate. EC type had a positive effect on egg production, feed conversion ratio, feather and foot condition, and breaking force of metatarsus.

Comparison of different brown and white layer hybrid embryonic development and uptake of nutrients in the egg.

The objective of this study was to evaluate the comparison of different brown and white layers in embryonic development and uptake of nutrients in the egg. A total of 360 fertilized eggs obtained from two brown (Atak-S and Brown Nick) and two white (Atabey and Nick) layer breeders at 28 wk old. Hatching eggs from each genotype were examined on the day of setting for fresh egg analysis and then at the beginning of the embryonic day (E19) and embryonic day (E21) for egg, embryo and villus analysis. Differences in egg weight, shell percentages, relative weight of yolk and albumen, relative weight and length of embryo, villus height, some values of shell, yolk and albumen and relative chick weight in examined hybrids were significant. Yolk sac utilization of embryos during the incubation in the white layer hybrids was greater than that in the brown layer hybrids. Villus heights in the duodenum, jejenum and ileum of embryos in the brown layer hybrids was greater than that in the white layer hybrids. Genotype is important parameter to determine the egg composition at the same age and in animals being fed the same diet. It was observed that the consumption of yolk and shell nutrients from the embryos during the incubation was not related to whether embryos were from the brown or white layer hybrids. Only uptake of the yolk sac and villus height in the embryo among examined variables varied depending on whether the embryos were from the brown or white layer hybrids.

Differences in egg nutrient availability and embryo development in white layer breeder genotypes.

Because of consumers' preferences and also due to changes in production systems, the importance of pure breeds has increased again. There are a lot of differences among breeds which have been studied extensively, however, the differences during the incubation period are not yet fully known. Therefore, the present study was conducted to evaluate the composition of the egg parts, absorption of nutrients, and development of embryos from different genotypes. A total of 354 fresh hatching eggs were obtained from one hybrid (Lohman White, LW) and two pure breeds (Denizli and Gerze). Hatching eggs from each genotype were examined on the day of setting for egg analysis and then at the beginning of the embryonic d 19 (E19) and embryonic d 21 (E21) for egg, embryo, jejunum, and tibia analysis. On d 21 of incubation, the healthy chicks were removed and weighed. Egg weight, shell thickness, percentages of albumen, and some parameters of albumen composition (dry matter, water, ash, protein, energy, Na, Ca, K, and Mg) were higher in fresh eggs obtained from LW hens. Furthermore, the relative yolk sac and embryo weight, some yolk parameters (dry matter, water, protein, fat, and energy) and some shell parameters (dry matter, ash, Na, Ca, and K) were also higher in eggs obtained from LW hens during incubation. However, tibia deformation and villus width were lower in LW embryos than the other genotypes. Relative chick weights were 68.9, 72.0, and 68.0% in LW, Denizli, and Gerze genotypes, respectively. During incubation, differences in all examined parameters were significant except thickness and weight of shell, tibia deformation, and crypt depth. Yolk sac weight, some yolk composition parameters, K level in the shell, Cu level in the tibia, and villus height were also affected by genotype and period interaction. Based on these results, LW was found advantageous in terms of egg composition, however, regarding villus development and tibia deformation in embryos during incubation, pure breeds showed better results.