The effect of different concentrations of rosemary extract spray on fertile eggs on embryonic parameters and quality of broiler

In the present experiment, the effects of different concentrations of rosemary extract(RE) spray on fertile eggs on the first day of incubation on embryonic parameters and quality of hatched chicks were investigated. Seven treatments were tested in a completely randomized design with five replicates, including five treatments of different concentrations of rosmarinic acid(RA) (0.5,0.1,1.5,0.2, and 2.55 mg/ml of RA) and two treatments of distilled water (with and without spray) on the first day of incubation. The results showed that the weight of the yolk sac of hatched chicks from eggs sprayed with a concentration of 2.55 mg/ml of RA was significantly lower than those from eggs treated with distilled water(P<0.05).There was no significant difference in hatchability percentage and embryonic mortality between unsprayed and sprayed eggs with distilled water compared to RE. The use of RE spray on egg caused a reduction in the body surface temperature(BST) of hatched chicks compared to those from unsprayed eggs(P<0.05). The length of the intestine of hatched chicks from eggs sprayed with 1.5 mg/ml of RA was greater than that of unsprayed and distilled water-sprayed eggs(P<0.05). Finally, the results showed that the spray of RE, with a concentration of 2.55 mg of RA, resulted in a heightened absorption of yolk sacs in hatched chicks compared to those eggs sprayed with distilled water. Moreover, an longer intestinal length was observed using a spray of 1.5 mg of RA, accompanied by a decrease in body surface temperature of hatched chicks in comparison to eggs without any spray.