Abstract

In-ovo injection with exogenous materials, such as natural antioxidants, throughout incubation could be a technique to boost hatchlings’ performance. The objective of the present study was to determine the effect of in-ovo injection of cinnamon, thyme, and clove extracts on the subsequent growth performances, immunity, and physiological responses of newly-hatched chickens. A total of 450 fertile eggs used in the current experiment were obtained from avian broiler breeder flocks of 28 weeks of age. The eggs were randomly distributed into five treatment groups which included three replicates for each one (30 eggs each group) in a completely randomized design at day 10 of embryogenesis. Treatment groups included a control group (P1: without any injection), the group received an injection of 0.5 ml deionized water (P2: sham group), and the groups injected with 0.1 ml cinnamon, thyme, and clove extracts (P3, P4, P5, respectively). The hatchlings from each treatment were randomly assigned to five replicates of 10 chickens, and reared until 35 days of age. The results showed no significant differences among groups in terms of feed consumption, serum albumin, and immunoglobulin’s A (IgA). Nevertheless, using extracts resulted in a significant increase in body weight and weight gain, and improved feed conversion ratio and immunoglobulin’s G and M (IgG and IgM), compared to the control and sham groups at 35 days of age. The injected extracts had significantly positive effects on serum lipids profile, liver functions (AST, ALT, and ALP) values, and antioxidant activity, compared to the control groups. Furthermore, serum concentrations of triiodothyronine and thyroxine were significantly higher in the group injected clove-extracted than in other experimental groups. According to the results, it can be concluded that in-ovo injection of herbal extracts, especially clove extract on day 10 of incubation has a positive effect on the broiler chickens’ weight at hatch and post-hatch performance as well as physiological, immunological, and anti-oxidative status of hatched chickens.