Anise and grape seed oils as a feed additive to improve the performance, immune response, and antioxidant activity and reduce caecal pathogenic microbes of quail

Abstract. This trial was performed to determine the effect of anise (Ans) and grape seed (Grp) oil inclusion in diets of Japanese quail on performance, carcasses, blood parameters, antioxidant activity, and hematological blood structure. The 35 d feeding trial was conducted on two hundred 7 d old Japanese quails, allocated to four treatment groups with five replicates each. Ans and Grp were examined at different inclusion levels: 0 % (control), Ans 0.5 %, Grp 0.5 %, and Ans 0.25 % + Grp 0.25 %, in a completely randomized design. The results showed that at the end of the trial (42 d), the oil supplementation had positive effects (P<0.001) on the productivity parameters, while feed intake (FI) did not differ from the control group. In addition, oil supplementation linearly improved (P<0.05) the dressing percentage, carcass yield, and immune organs' relative weights, while it decreased (p<0.01) the abdominal fat yield. Plasma total protein (TP), albumin (Alb), and globulin (Glob) were significantly increased in the Grp group. Despite total plasma cholesterol not being significantly affected by treatments, Ans and Grp essential oils decreased low-density lipoprotein cholesterol (LDL) and increased high-density lipoprotein cholesterol (HDL). Moreover, total antioxidant capacity (TAC) concentration was increased (P≤0.001) in the treated groups, while malondialdehyde (MDA) decreased (P≤0.001). Results of a caecal bacterial count revealed that Ans and its combination with Grp led to an increase (P≤0.001) in Lactobacillus spp. count. On the other hand, Ans, Grp, and their combination led to a significant reduction (P≤0.001) in E. coli spp. and Salmonella spp. compared to the control group. It is concluded that Ans and Grp seed oils could be used as valuable essential oils in quails' diets to improve the performance and immune response, enhance the antioxidant activity, and reduce caecal pathogenic microbes.