ABSTRACT
Background and Aim: Successful rearing of laying hens to achieve optimal egg production is an endeavor that often faces various constraints and challenges, such as infectious diseases, environmental stressors, and fluctuations in feed quality. The incorporation of essential oils (EOs) into the diet of laying hens has attracted considerable attention in recent years. Therefore, our study aimed to evaluate the efficacy of EO inclusion in laying hen diets by considering the effects of production phase and breed on performance, egg quality, serum biochemistry, gut health, and antioxidant activity. Materials and Methods: The articles were obtained from the Web of Science, Scopus, Science Direct, and PubMed using the search terms "essential oils," "laying hens," and "phytobiotics." Data from 27 articles and 71 experiments were grouped according to laying hen production phase and breed in the database. The EO levels ranged from 0 to 1000 mg/kg, with thymol and carvacrol being the major EOs. A mixed model was used to analyze the data. Random effects were applied to the treatment, and fixed effects were applied to EO level, production phase, and breed. Results: Egg production, feed intake, feed efficiency, eggshell quality, villus height, crypt depth, superoxide dismutase, and glutathione peroxidase levels increased linearly (p = 0.05) and egg weight and mass increased quadratically (p < 0.05) with increasing EO concentrations. An interaction was observed between the EO level egg production and feed conversion ratio (p = 0.05). Serum glucose, cholesterol, and malondialdehyde levels decreased with increasing EO concentrations (p < 0.05). Conclusions: The inclusion of EOs effectively increased egg production, feed efficiency, egg weight, egg mass, eggshell quality, oxidative enzymes, and intestinal health. In addition, the proportion of dietary EOs in lightweight laying hens was higher than that in semi-heavy-weight laying hens in improving egg production and feeding efficiency.
ABSTRACT
The aim of the study was to investigate the effects of infused olive leaves (IOL) in drinking water on the growth performance, carcass characteristics, ileal histomorphology, and cecal microorganisms of broiler chickens. A total of 210 day-old male broiler chicks were randomly divided into 5 treatment groups with 6 replicates and 7 chicks in each replicate. All chicks received a corn-soybean-based diet and drinking water with or without IOL ad libitum for 42 days. Treatments were drinking water without any additives (control group), drinking water including IOL of 5 m/L (IOL5), 10 m/L (IOL10), 15 ml/L (IOL15), and 20 ml/L (IOL20). The addition of IOL to drinking water did not affect the growth performance, water intake, carcass parameters, weights of inner organs, and digestive tract weight and length. The Escherichia coli and Lactobacillus spp. counts in the cecum were also not influenced by IOL supplementation in drinking water. However, chickens receiving IOL5, IOL10, or IOL15 had higher villus length in the ileum compared with birds in the control group. Crypt depth was lower in chickens from the IOL20 group compared with birds in the other treatment groups. In addition, broilers offered IOL15 or IOL20 had a higher villus length to crypt depth ratio in the ileum than chickens in the control group. However, treatments had no influence on the lamina muscularis mucosae layer of the ileum in broiler chickens. The results showed that drinking water including IOL at 15 and 20 ml/L improved ileal histomorphology without any detrimental effect on growth performance, carcass traits, and cecal microorganisms in broiler chickens.
