Effects of dietary incorporation of Radix rehmanniae praeparata polysaccharide on growth performance, digestive physiology, blood metabolites, meat quality, and tibia characteristics in broiler chickens

Radix rehmanniae preparata polysac-charide (RRPP) is recognized as the primary bioactive compound in Radix rehmanniae preparata and has been extensively utilized in traditional Chinese medicine and functional food due to its diverse biological activities. However, this study has yet to explore the application of RRPP as a feed additive in broilers. This study investigated the effects of dietary RRPP on growth performance, meat quality, and physiological responses of broiler chickens. Two hundred eighty-eight 1-day-old Cobb 500 male broilers were randomly assigned to the 4 experimental groups with 6 replications and 12 birds/re-plicate. The 4 groups were fed the basal diet supplemented with 4 concentrations of RRPP (0, 300, 600, and 900 mg/kg, respectively). All RRPP levels did not affect the growth performance of broilers during the starter period (1-21 d), while during the grower (22-35 d) and overall (1-35 d) periods, body weight gain, feed conversion ratio, and European production efficiency index were linearly improved (P < 0.05) by incorporating RRPP at 600 and 900 mg/kg. Carcass characteristics, relative weight and length of intestinal segments, and meat quality and tibia criteria were not affected by dietary incorporation of RRPP. Dietary RRPP led to a linear increase (P < 0.05) in serum alkaline phosphatase, potassium, calcium and sulfhydryl levels, while reducing concentrations of hydrogen peroxide, LDL, triglycerides and total cholesterol. The addition of RRPP decreased (P < 0.05) the pH of the ileum and cecum at 21 and 35 d of age while not changing in the remaining intestinal segments. Dietary RRPP at 600 and 900 mg/kg linearly and quadratically (P < 0.05) increased the tibia ash con -tent in chicken at 21 and 35 d of age. In conclusion, dietary supplementation of RRPP improved broiler chicken's growth, gut physiology, and tibia ash content, particularly at 600 and 900 mg/kg.