Abstract
The chicken egg is one of the most globally-consumed animal protein sources with high-quality protein value. However, there is a growing concern about the association between excessive egg consumption and the increasing risk of cardiovascular disease incidence. Meanwhile, corn silk extract (CSE) is known to have hypo-lipidemic bioactive properties, as well as antioxidant and anti-inflammatory effects. Thus, the present study was designed to investigate the effect of feeding laying hens three different CSE levels on egg cholesterol content as well as egg production performance and oxidative stress marker levels. A total of 240, 40-week-old, Hy-Line Brown laying hens were divided into 4 symmetric groups (10 hens x 6 replicates). The control group was fed a basal diet while the other three groups were given the basal diet supplemented with 100 mg, 200 mg, or 400 mg CSE per kg feed, respectively. Egg production performance was monitored for eight successive weeks. Internal and external egg quality parameters were also measured. At the end of week 48 of age, blood samples were collected to determine the plasma lipid profile, stress markers, and liver function indicators. Data revealed that supplementation of 200 mg and 400 mg CSE to laying hen diets had a positive effect on egg production performance with a significant increase in egg numbers and egg weight as well as significantly improved feed efficiency. Egg quality parameters were significantly improved with CSE supplementation. Lipid peroxidation levels and inflammation marker concentrations significantly decreased for the experimental groups that were fed 200 mg and 400 mg CSE compared with the control group. Meanwhile, blood total cholesterol decreased significantly with CSE supplementation, along with an increase in high-density and a decrease in low-density lipoprotein cholesterol content. A high positive correlation was found between liver and egg cholesterol contents (r = 0.902, p < 0.0001) which was linearly decreased with the increasing level of CSE supplementation. Egg cholesterol content significantly decreased by 9 to 19% in the CSE-supplemented groups compared with the control group. The present study demonstrated that CSE at 100 mg/kg and up to 400 mg/kg diets can be safely used to improve laying hen egg production performance with a direct effect on lowering egg cholesterol content as well as improving the redox status.