In recent years, there has been growing interest in exploring the potential health benefits of incorporating
natural plant substances into the diets of farm animals. Basket willow (Salix viminalis), rich in flavonoids,
tannins, and salicylates, has emerged as a candidate with analgesic, anti-inflammatory, and anthelmintic
properties, making it appealing for integration into ruminant farming practices. This study aimed to analyze the
effects of dietary supplementation with basket willow on the neuroanatomical properties of the small intestine
in farmed fallow deer. Immunohistochemical methods and morphometric measurements were employed to
assess changes in noradrenergic, galaninergic and nitrergic innervation patterns. Twenty-four fallow deer
were divided randomly, with 12 individuals placed in both a control group and an experimental group, with
the latter receiving willow supplementation. The results revealed significant alterations in the morphology
and innervation patterns of the enteric nervous system (ENS) in the experimental group, including a decrease
in ganglion size and nitric oxide synthase (NOS) immunoreactive nerve fibers, and an increase in galanin
immunoreactive neurons. These findings suggest a potential modulation of gastrointestinal function by willow
supplementation. However, caution is warranted due to the high salicylate content in basket willow, which
may pose risks to gastrointestinal integrity. Overall, while basket willow supplementation shows promise in
enhancing animal farming methods, further research is needed to elucidate its mechanisms and optimize its
use in ruminant farming practices.