Influence of in Ovo Injection of Phytochemicals and Post-Hatch Feeding on Hatching Traits, Physiological Aspects, Productive Performance, Duodenal Morphology, and Digestibility of Broiler Chickens

In poultry research, many phytochemicals extracted from various plants proved their nutritional and physiological functions by inhibiting stressful conditions. This study aimed to examine the effect of in ovo injection (IOI) of limonene (LN), cinnamaldehyde (CN) and menthol (ML) followed by post-hatch feeding method (FM), including early feeding (EF) and late feeding (LF) of broiler chicks on hatching, physiological and productive responses up to 35 days. Nine hundred eggs were used and divided into five groups, and each group had four replicates (45 eggs/replicate).  One group was without IOI (negative control), whereas other groups were IOI on day 18 of embryogenesis with 100 μL of dimethyl sulfoxide or 5 mg/100 μl each of LN, CN and ML. After hatching, 760 birds were equally divided into 10 treatments of 4 replicates based on FM into EF in the hatchery or LF on the farm. A completely randomized design was conducted and the main effects of IOI×FM were analyzed in a 5×2 factorial arrangement at P ≤ 0.05. The results showed that IOI of ML increased hatchability and chick length. LN group caused to increase body weight at hatch and villus dimensions whereas CN group shortened incubation period. All IOI groups depressed mortality and lipid hydroperoxide and  elevated levels of thyroxine and nutrient digestibility. Both ML and CN groups enhanced body weight and total antioxidant capacity with lowered malondialdehyde, cholesterol, aspartate transaminase and gamma-glutamyl transferase values . Low feed intake and high catalase were obtained by both CN and LN groups. Moreover, low levels of corticosterone, glucose and creatine phosphokinase were acheived by ML and LN groups with lowered uric acid in CN group. The main effect of EF improved all determined characteristics compared with LF and  each interactive treatment between IOI and FM behaves in specific manner to exhibit its desirable effect. It has been concluded that IOI of these phytochemicals could improve hatching results and their synergetic effects with post-hatch EF optimized productive performance due to multiple physiological mechanisms.