Effects of housing systems, flock variables, and storage conditions on internal egg quality in Israel

The current study aimed to evaluate the internal quality of Israeli eggs, exploring the influence of various pre-laying factors, mainly the housing system type and flock size, on internal egg quality. The study used a stratified random sample of eighty flocks, representing Israel's layer population, categorized by housing system (cage/non-cage) and flock size (≤/>10,000). A total of 1,600 eggs were tested using Haugh unit (HU) measurements. Additional 2,800 eggs were used to monitor internal egg quality over a period of 28 days at storage temperatures of 20°C and 4°C. The housing system (cage/non-cage) had no effect on internal egg quality as measured by HU, but for caged farms, egg quality was higher in small flocks. Internal egg quality was primarily influenced by the layer flock age, with older hens producing larger but lower-quality eggs. Additional factors impacted internal egg quality, but to a lesser extent: Newcastle disease (ND) when diagnosed in a flock, lowered egg quality. Higher percentage of protein in the feed (above 17%) improved egg quality; and the Dekalb strain had a higher egg quality compared to the Hy-Line breed (with no significant difference found between the major breeds Lohmann and Hy-Line). Eggs kept at low storage temperature (4°C) maintained their quality, in comparison to eggs kept at room temperature (20°C). This research sheds light on factors affecting internal egg quality in the Israeli egg industry and highlights the importance of proper storage conditions to preserve egg quality for consumers.