Abstract: 【Objective】 The experiment aimed to evaluate the application effects of phased malic acid (MA) diet in broiler production. 【Method】 A total of 480 one-day-old Cobb male broilers were randomly divided into 4 treatments,with 8 replicates per treatment.The broilers in control group were fed a corn-soybean based diet throughout the entire period.The broilers in experimental groups were fed experimental diets supplemented with 0.4%,0.6%,and 0.8% MA from 1 to 14 days of age,and then were fed the basal diet from 15 to 42 days of age.This experiment lasted for 42 days.Growth performance was recorded during the rearing trial.After the trial,the broilers were slaughtered,and carcass traits were assessed.Additionally,samples of chicken breast,blood,and intestinal tissue were collected to evaluate meat quality,blood biochemistry,intestinal antioxidant capacity,and cytokine levels. 【Result】 Compared with the control group,① The addition of 0.4% MA in the diet during the early growth phase increased the average daily gain (ADG) of broilers from 1 to 14 days of age,reduced the feed conversion ratio,and increased the average body weight at 14 days of age (P＜0.05).And it decreased the drip loss and cooking loss of muscle,as well as the serum low-density lipoprotein cholesterol levels (P＜0.05).② The addition of 0.6% MA in the diet during the early growth phase increased ADG of broilers from 1 to 14 days of age (P＜0.05),reduced muscle shear force (P＜0.05),it also decreased serum alanine aminotransferase activity and total protein levels (P＜0.05),and reduced the content of interleukin-1β (IL-1β) in jejunal mucosa (P＜0.05).③ The addition of 0.8% MA in the diet during the early growth phase decreased the abdominal fat percentage of broilers at 42 days of age,significantly increased the activity of intestinal superoxide dismutase,and significantly decreased the activity of intestinal catalase (P＜0.05),and also reduced the content of IL-1β,IL-2,and tumor necrosis factor in the jejunal mucosa (P＜0.05). 【Conclusion】 The addition of 0.4% to 0.6% MA in the diet during the early growth phase could improve the growth performance of broilers from 1 to 14 days of age,enhance the meat quality of broilers at 42 days of age,and strengthen their intestinal antioxidant capacity and immune levels.However,the addition of 0.8% MA in the diet during the early growth phase had an adversely affect on the intestinal antioxidant capacity and immune performance of 42 days of age broilers.

Key words: malic acid; broiler; growth performance; meat quality; serum biochemistry; intestinal health