Effect of olive leaf incorporation in animal feed on broiler turkey (<i>Meleagris gallopavo</i>) growth performance, welfare, oxidative status, and blood and biochemical serum parameters

Abstract

This work investigates how incorporating olive leaves (OLs) (Olea europaea) into turkeys' (Meleagris gallopavo) diets affects their performance, welfare, blood biochemical parameters, and oxidative status of those reared in intensive farming conditions. The potential of this ingredient was assessed by comparing two dietary incorporation rates of olive leaves, 3 % and 6 %, in three commercial feeds corresponding to three growth phases over 15 weeks where feed was provided ad libitum. A total of 270 animals (broiler medium strain) were used. They were divided into three groups: the OL0, OL3, and OL6 regimens with OL incorporation rates of 0 %, 3 %, and 6 %, respectively. Animals were allocated to three pens of approximately 15 m2 of surface area; each pen had 30 animals, with a density of three turkeys per square meter. Throughout the rearing period, the diet had no effect on bird mortality. Olive leaves boosted growth rates. Indeed, after the experiment, the OL3 group had significantly higher weights than the OL6 and OL0 groups, which had the lowest feed conversion ratio. Furthermore, after bleeding, the weights and evisceration was significantly (p < 0.05) higher in the OL3 and OL0 groups compared to the OL6 group. However, OL0 turkeys had significantly higher spleen, heart, and abdominal fat weights than OL3 and OL6 turkeys. The three experimental groups had no significant differences (p>0.05) in carcass yield or gizzard or liver weights. OL supplementation improved oxidative status but had no effect on animal welfare or blood biochemical parameters, with the exception of the mean corpuscular hemoglobin concentration (MCHC), which was significantly (p < 0.05) lower in the OL3 group than in the OL0 and OL6 groups. Except for the mean cholesterol level, which was significantly (p < 0.05) lower in the OL3 and OL6 (1.29 g L−1) groups compared to the OL0 group, and the albumin level, which was higher in the OL0 group compared to the OL6 group, no significant effect was observed on biochemical serum parameters. Thus, a 3 % OL supplementation in the turkey diet appears promising for improving the bird's growth performance.