Efficiency on performance, carcass properties and blood parameters of essential oil mixture protected by two different methods of mixed feed in quails under heat stress exposure

The present study was conducted to determine the effects of essential oil mix (orange peel oil + bay leaf oil + thyme oil) added into basic mixed feed on performance parameters, carcass traits, some blood parameters, antioxidant parameters, and the organ weights of digestive system in quails (Coturnix coturnix Japonica) exposed to heat stress. Totally 96 quails from both genders were used including 32 animals in each group in the study. Every group were divided into 4 subgroups including 8 quails in each one. The animals were exposed to 34±2oC of heat stress for 8 hours (9.00-17.00) per day. Heat stress treatment was applied for 28 days. The study groups were as follows; Control group which was exposed to heat stress and received basic mixed feed only with zeolite, Zeolite group which was exposed to heat stress and received 200 ppm dose of essential oil mixture stabilized with zeolite added into mixed feed, and Capsule group which was exposed to heat stress and received the mixed feed added with 200 ppm dose of essential oil mixture stabilized by microcapsulation. In the study, the highest live weight (43. day), live weight gain (15-43. days), and feed conversion ratio were obtained in the capsule group (P<0.05). There was no statistically significant difference between the groups in terms of feed consumption and organ weights of digestive system (P>0.05). The highest values were determined from capsule group in terms of slaughter weight (P<0.05), weight of spleen (P<0.01), and ratio of spleen (P<0.05). Hot carcass weight and carcass performance were found to be statistically higher in groups receiving feed with essential oil mixture than control group (P<0.05). In the trial, it was determined that while the lowest levels of glucose (P<0.01), uric acid, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were observed in capsule group (P<0.05), control group had the highest cholesterol and triglyceride levels (P<0.05). While the lowest malondialdehyde (MDA) levels of liver (P<0.05) and heart (P<0.001) were determined in capsule group, the highest glutathione peroxidase (GSH-Px) levels of liver (P<0.01) and heart (P<0.05) were also observed in capsule group. Reduced glutathione (GSH) (P<0.05) and superoxide dismutase (SOD) (P<0.01) levels in liver and GSH (P<0.01) enzyme levels in heart were higher in groups receiving feed with essential oil than control group. A statistical difference was not found between the groups in heart SOD levels (P>0.05). The study did not reveal a statistically significant difference between the groups in terms of mortality ratio (P>0.05). In conclusion, essential oils used due to their antioxidant properties were determined to decrease negative influences of heat stress. It was concluded that the efficiency of microcapsulation method used for stability of essential oils was higher than zeolite absorption method and the use of essential oils in stability processes can increase the performance thought to be obtained from animals.