Dietary halloysite supplementation in Orvia ducks: effects on production performance, meat quality, blood biochemistry, muscle histological and molecular traits.

The study evaluated the effects of dietary halloysite supplementation on growth performance, carcass traits, meat quality, blood biochemical parameters, intestinal microbiota, muscle histology and selected gene expression in Orvia ducks, with consideration of sex-dependent responses. A total of 200 one-day-old Orvia ducks were allocated to control and halloysite-supplemented groups, with males and females analyzed separately. Birds in the experimental groups received diets supplemented with 1% halloysite throughout a 42-day rearing period. Growth performance, carcass composition, physicochemical and chemical traits of pectoral and leg muscles, post-mortem blood biochemical parameters, bacterial populations in intestinal segments, histological traits of the pectoral muscle and relative expression of selected metabolic genes were assessed. Halloysite negatively affected body weight and body weight gain during the first rearing period, but final body weight and total body weight gain were not significantly changed. Feed conversion improved during the later growth phase. Halloysite modified selected meat quality and chemical composition traits, including protein, intramuscular fat, water content, redness and water-holding capacity. Treated birds showed higher total protein and lower uric acid and urea concentrations, while liver enzymes and systemic lipid profile remained unchanged. No statistically significant differences were found in the analyzed bacterial populations or muscle histological traits. Gene expression changes were mainly limited to FST and CEBPB, treatment- and sex-associated variation in the transcript abundance of genes related to muscle growth and metabolic regulation. Dietary supplementation with 1% halloysite induced selective metabolic and molecular responses without impairing final growth performance or muscle microstructure. The observed sex-dependent effects indicate that sex should be considered when assessing halloysite supplementation in broiler duck production.