Effects of Dietary Schizochytrium species powder on Broiler Growth Performance, Blood Parameters, and Gut Microbiota

This study investigated the effects of supplementing Ross 308 broiler diets with DHA-rich Schizochytrium sp. powder (SP) on growth performance, nutrient digestibility, serum biochemical parameters, and gut health. A total of 120 broilers were randomly assigned to four dietary treatments: the control group (Control: basal diet) and three experimental groups (Group L: basal diet supplemented with 6.25 g/kg SP; group M: basal diet supplemented with 9.375 g/kg SP; group H: basal diet supplemented with 12.5 g/kg SP). The 49-day experiment consisted of a basal diet feeding phase from 0 to 3 weeks, followed by treatment-specific diets from 4 to 7 weeks. The results showed that: (1) no significant differences (P > 0.05) were observed in average daily gain (ADG) or feed-to-gain ratio (F/G) among the groups; however, during the late stage of supplementation with Schizochytrium sp. powder, the H group exhibited a significantly lower average daily feed intake (P < 0.05); (2) serum total protein (TP) levels were significantly higher in the L group (P < 0.05); (3) the apparent digestibility of crude fat and crude protein was significantly improved in all experimental groups compared to the control (P < 0.05); (4) the villus height to crypt depth ratio (V/C) in both the jejunum and ileum increased significantly (P < 0.05), suggesting enhanced nutrient absorption capacity; (5) Schizochytrium sp. powder supplementation promoted the proliferation of beneficial cecal bacteria such as Akkermansia and Faecalibacterium, which may be attributed to its high DHA content and contributes to strengthening the intestinal barrier function through modulation of the gut microbiota structure. Overall, the M group demonstrated the most favorable outcomes in terms of intestinal microbiota balance, intestinal morphology, and functional improvement, leading to better nutrient utilization and production performance. Therefore, identifying the optimal inclusion level of DHA-rich Schizochytrium powder in broiler diets is essential for maximizing economic efficiency and overall feeding efficacy.