It was assumed that the addition of a phytobiotic preparation containing cinnamon oil and citric acid to water, at a properly selected dose and time of application, could reduce the occurrence of metabolic disorders of the nervous tissue leading to neurodegenerative lesions. The aim of the study was to compare the effect of selected doses of the phytobiotic administered over different periods of time on the level of parameters indicating the occurrence of neurodegenerative changes in selected tissues of broiler chickens. All doses of the phytobiotic reduced the formation of β-amyloid deposits both after its continuous administration and during selected rearing periods. The levels of neurometabolism indicators were analysed to assess the effect of the phytobiotic containing cinnamon oil. The addition of the highest and medium doses of the phytobiotic (0.25 and 0.1 ml/l) resulted in a beneficial increase in the concentration of acetylcholinesterase (AChE) and low-density lipoprotein receptor-related protein 1 (LRP1), as well as a decrease in the concentration of hyperphosphorylated Tau protein and cholesterol levels, especially during continuous application of the cinnamon preparation. The highest dose of phytobiotic (0.25 ml/l) also favourably reduced glycosylated acetylcholinesterase (GAChE) and Tau protein levels, and the strongest effect was obtained during continuous application of the cinnamon oil formulation. The strongest neuroprotective effect was obtained using a phytobiotic containing cinnamon oil and citric acid at a dose of 0.25 ml/l water for 42 days of rearing broiler chickens, manifested as a reduction in the formation of toxic amyloid-β, phosphorylated Tau protein and GAChE, as well as increased levels of LRP1 and AChE proteins.