Effects of dietary fennel (Foeniculum vulgare Mill.) seed powder supplementation on growth performance, nutrient digestibility, small intestinal morphology, and carcass traits of broilers

BACKGROUND: With the increasing demands in livestock and poultry breeding and the growing number of food-borne diseases, it is necessary to practice food safety and develop strategies to produce healthy livestock. Fennel (Foeniculum vulgare Mill.) has been used as an additive in poultry production by some researchers, but there are few studies on the systemic beneficial effects of dietary fennel seed powder supplementation on broilers. Therefore, this study aimed to investigate the effect of dietary fennel seed powder supplementation on feed intake, the apparent metabolic rate of nutrients, intestinal morphology, and carcass traits in Cobb broilers. METHODS: A single-factor experimental design was used. In total, 160 1-day-old Cobb broiler chicks were randomly assigned to four treatments, with four replicates each (n = 10/replicate). Broilers in the control (CN) group were fed a basal diet without fennel seed powder, and broilers in the treatment groups were fed a basal diet supplemented with 0.15% (LF), 0.30% (MF), or 0.45% (HF) fennel seed powder, respectively. Feeding trials lasted for 42 days under the conditions of ad libitum access to feed and water, and 24-h illumination. During the third and sixth weeks, digestive and metabolic assays were carried out. When the broilers were 42 days old, one chicken with a weight close to the average was selected from each repetition, euthanized by an intravenous injection of 5% sodium pentobarbital, and carcass traits were measured and intestinal samples were collected for morphological assessment. RESULTS: There was no significant difference in growth performance of broilers (P > 0.05). The breast muscle percentage, fat width and fat width index, breast muscle area, and breast muscle area index of broilers in the LF group were higher than those in other groups (P < 0.05). Jejunum weight and length were higher in MF than in CN and LF broilers (P < 0.05). Additionally, duodenal villi height, ileal villi height, and ileal wall thickness were higher in MF than in CN broilers (P < 0.05). There were no significant differences in nutrient utilization among all groups (P > 0.05), except that the ash apparent metabolic rate in MF broilers at 21 days of age was higher than that in LF broilers (P < 0.05). In conclusion, dietary supplementation with a moderate concentration of fennel affects carcass performance, and intestinal morphology, and promotes the growth and development of broilers.