Broiler Responses to a Phytogenic Nutritional Additive Under Different Dietary Nutrient Matrix Credit Strategies

This study evaluated the physiological and production responses of broilers to a phytogenic nutritional additive (PNA) applied under different dietary nutrient matrix credit strategies. The PNA contained star anise essential oil, thyme essential oil, and Quillaja saponaria Molina stem and leaf powder, with trans-anethole, p-cymene, and thymol as the main characterized marker compounds. A total of 384 one-day-old male Arbor Acres broilers were assigned to four treatments (eight replicates of 12 birds): a basal control diet without PNA (CON) and PNA-supplemented diets using full matrix credit (PNA-FM), protein matrix credit (PNA-PM), or no matrix credit (PNA-NM). Growth performance was unaffected (p > 0.05), whereas all PNA-supplemented groups had higher dressed percentages and eviscerated yields than CON (p < 0.01). PNA-PM and PNA-NM increased the muscle pH (p < 0.01), and PNA-NM increased drip loss and shear force (p < 0.05). Intestinal responses were time-dependent: on day 14, PNA-NM increased serum FITC-d, tended to increase DAO activity, and downregulated ZO-1 expression, while all PNA-containing treatments reduced the villus height and villus height-to-crypt depth ratio (p < 0.01), suggesting a transient epithelial adjustment rather than direct barrier improvement. On day 22, qualitative TEM observations suggested closer epithelial junctions in PNA-containing treatments. These results indicate that PNA-containing formulation strategies did not compromise growth performance and modified carcass traits, meat quality traits, intestinal responses, and the excreta nutrient composition. Because PNA-free full matrix and protein matrix control diets were not included, these findings should be interpreted as responses to complete dietary strategies rather than as formal PNA × nutrient matrix interactions.