Effects of garlic and lemon essential oils on performance, digestibility, plasma metabolite, and intestinal health in broilers under environmental heat stress

Background Natural feed additives play an important role in poultry production due to their safety and potential properties as an antioxidant and antimicrobial, as well as a growth stimulant. The present research was designed to assess the influence of dietary supplementation of either garlic, lemon essential oil, or their mixture on performance, nutrient digestibility, plasma constituents, immunity, and oxidative status, as well as intestinal development assessed by microbiota—histomorphology development in broilers under environmental heat stress. Methods A total of 480 broiler chicks (Ross 308) at one-day-old were randomly divided into four groups (120 chicks/ group). The control group received the basal diet (CON), while the other three groups received the basal diet supplemented with 200 mg/kg garlic essential oil (GEO), 200 mg/kg lemon essential oil (LEO), and their mixture (GLO) 200 mg/kg diet, respectively for 35 days. Results The obtained results revealed that broilers fed essential oils as a mixture or individually had an improvement in average body weight, feed conversion ratio, carcass dressing, and an increase in digestive enzymes activities compared to the control group, furthermore, there was a reduction in the mortality rate and abdominal fat content. Adding essential oils as a mixture or individually led to a decrease in ( P < 0.05) blood plasma triglycerides, cholesterol, low-density lipoprotein, and an increase in high-density lipoprotein. Broilers fed diets supplemented with essential oils as a mixture or individually had higher values of superoxide dismutase and glutathione peroxidase; while plasma malondialdehyde was lower ( P < 0.05) compared to the control diet. Moreover, there was a significant enhancement in intestinal microbial content, and intestinal histological status of chickens fed with essential oils. Conclusions Conclusively, including the mixture of essential oils improved performance, nutrient digestibility, and digestive enzymes activities. It also enhanced immunity, antioxidant state, and lipid profile, and gut microbiota— histomorphology in broilers. It was proposed that the broilers diet be supplemented with a mixture of essential oils to a mitigation of the effects of heat stress.