Dietary Gamma-Oryzanol and Vitamin E Tocotrienols Mitigates Negative Impacts on Productivity, Egg Quality, and Immune- and Health-Related mRNA Abundance in Laying Hens Reared under High Cage Density

A 4×2 factorial experiment was conducted to evaluate the potential of feeding dietary gamma-oryzanol and vitamin E tocotrienols in hens reared in 840 (low cage density; LCD) or 420 cm2/hen (high cage density; HCD). A total of 120 hens were allocated into eight groups with five replicates. Diets were a control (CON) or the control diet supplemented with 200 ppm gamma-oryzanol (GO-200), 200 ppm vitamin E tocotrienols (VE-200) or 200 ppm gamma-oryzanol + 200 ppm vitamin E tocotrienols (GE-400). Results showed that HCD-housed hens decreased (P < 0.01) egg performance and quality. Average egg weight (AEW), egg mass and FCR improved in all supplemented treatments. Results on the AEW, FCR, and eggshell qualities of birds kept at the HCD revealed the best responses in the GE-400 group (P < 0.01). Among hens kept on an HCD, there was a noticeable decrease in HMGCR mRNA abundance in the VE-200 group, while the highest IFN-γ mRNA abundance was found in hens fed the GO-200 diet (P < 0.05). Thus, this study suggested that dietary GO or VE at 200 ppm either individually or in combination could improve performance and egg quality as well as regulate the abundance of immune- and stress-related genes.