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This study compared egg quality parameters in layers under free-range system with prefabricated pens and backyard while emphasizing hen age. A total of 300 eggs collected from prefabricated pens and backyard farming families in the Çamardı District of Niğde Province were used as study materials. The assessed external and internal egg quality characteristics included egg weight, shape index, shell thickness, shell breaking strength, albumen index, Haugh unit, yolk index, and yolk colour. The effect of production system on albumen index, Haugh unit, and yolk colour score was found statistically significant. There was a significant effect of age on shape index, shell thickness, shell breaking strength, albumen index, Haugh Unit, yolk index, and yolk colour score. The effect of interaction between age and production system was statistically significant for shape index, shell thickness, yolk index, Haugh Unit, and yolk colour score. It was determined that the egg`s meat and blood spots percentages from the free-range and backyard systems were 10.6% and 15.3%, respectively. It was concluded that while eggs produced from free-range system are superior in terms of egg weight, shape index, and Haugh unit those obtained from backyard hens are higher in eggshell thickness, eggshell breaking strength, and egg yolk colour.

This paper reviews the effects of environmental enrichments in different laying hen production systems on hen welfare and egg quality. To improve hen welfare, several studies have investigated various environmental enrichments that suit different laying hen production systems. The positive results of these studies can enable such environmental enrichments to be utilized in commercial laying hen production. In this review, the most studied environmental enrichments in the free-range production system include forage, shelterbelt, and artificial shade in the outdoor area and novel objects and H-shaped perching structures in the indoor. These are associated with increased range use that positively affects hen welfare. In the aviary system, perches, and litter materials (e.g., straw, sand) as environmental enrichments are linked to improved behavioral expression, reduced stress, and enhanced immune system. Under the litter system, environmental enrichment with substrates (e.g., pecking stones, alfalfa blocks, silage, straw, barley) has been found to increase the foraging behavior of laying hens. This reduces severe feather pecking thus improving the plumage condition of hens. Although the effects of environmental enrichments on hen welfare have been assessed and scientifically proven in the reviewed studies, enough progress of their impact on egg quality traits has not been reported. The studies have shown that environmental enrichments have no significant effect on egg quality traits. On the other hand, appropriate pasture plants as environmental enrichments in the free-range production system in relation to hen welfare and egg quality have not been identified. Therefore, it is important to continue studies on environmental enrichments while emphasizing their influence on egg quality since it is a major performance trait in the egg industry. In addition, there is a need for studies to determine the ideal pasture species in the free-range production system that positively affects hen welfare and egg quality.

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