Effects of dietary fennel volatile oil on performance, egg quality, and egg yolk oxidative stability of laying quails

Abstract

This study was conducted to determine the effects of adding different levels of fennel volatile oil (VO) to the laying quail diets on performance, internal-external egg quality parameters, and eggs's oxidative stability. A total of 105 (6-week-old) laying quails (Coturnix coturnix Pharaoh) were used, and the quails were separated into 3 treatment groups, including 5 replicated sub-groups. A basal diet not containing fennel VO was formulated for the control group, and fennel VO was added to the basal diet at the levels of 200 and 400 mg/kg for Group 1 and Group 2, respectively. Diets and water were provided to quails ad libitum. Treatments continued for 56 days. As a result, the addition of fennel VO to the quail diets did not affect feed efficiency, haugh unit, egg yolk color, egg weight, shape index, or egg shell breaking strength. However, both levels of fennel VO increased feed intake (P<0.05), egg production (P≤0.001), eggshell thickness (P<0.001), and the rate of damaged eggs (P<0.05). Although there is no difference in malondialdehyde (MDA) levels of egg yolks stored at +4 °C on day 1, both levels of fennel VO significantly reduced MDA levels of egg yolks on days 7 and 28 (P<0.01). The fact that fennel VO could be added to poultry rations as a natural feed additive to increase performance, improve eggshell quality, and minimize storage losses by extending the egg shelf life was concluded based on the data obtained.