Dietary Effects of Some Plant Extracts on Laying Performance, Egg Quality, and Some Blood Parameters in Laying Hens at Different Cage Densities

Abstract

This study was carried out to determine the effects of cage density and anise extract (AE), thyme extract (TE), and black cumin extract (BCE) supplementation in the diet of laying hens on laying performance, egg quality, and some blood parameters. A total of 288 Lohman White commercial hens were blocked according to the location of their cages. The four dietary treatments included a control, basal diet + 250 mg/kg of AE, basal diet + 250 mg/kg of BCE, and basal diet + 250 mg/kg of TE for 12 weeks. The cage density affected egg production (p < 0.05), feed consumption (p < 0.01), and cracked eggs (p < 0.05). Increasing the cage density caused a linear decrease in egg production and feed consumption. Compared to the control, there was a decrease in feed consumption (p < 0.01) in the plant extract groups, and in parallel, egg production decreased. An increased cage density did not affect the egg quality traits except the shell strength. The shell strength, yolk color, yolk index, albumen index, and Haught unit were significantly affected by the plant extracts. The cage density and plant extracts had a significant effect on the serum corticosterone and glucose (p < 0.01). The highest values of corticosterone and glucose were recorded for dietary TE with a cage density of 4 birds/cm2. On the other hand, the lowest values of these parameters were recorded for AE addition with a cage density of 3 birds/cm2. As a result, an increased cage density was associated with stress and depression in the feed consumption and metabolic profiles. Supplemental AE, BCE, and TE improved the laying performance and metabolic profiles.