The effect of amylase, chromium propionate and their combination supplementation on growth performance, carcass traits, serum parameters, antioxidant capacity and intestinal health in yellow feathered broilers.

To better understand the growth promotion mechanism of amylase and chromium propionate (Cr Prop) and assess their potential synergistic effects, a total of 640 one-day-old male yellow-feathered broilers were randomly allocated to four dietary treatments with eight replicates. The birds were fed either a basal diet or the basal diet supplemented with amylase, Cr Prop or a combination of both. The results showed that during the grower, finisher and overall phases, average daily feed intake, final body weight, and feed conversion ratio were significantly improved (P < 0.05) in the amylase and Cr Prop treatment groups. However, no significant differences (P > 0.05) were observed in carcass traits. Amylase supplementation alone significantly reduced breast muscle drip loss (P < 0.05). Amylase supplementation significantly increased (P < 0.05) the concentration of glutathione peroxidase in breast muscle and plasma, as well as catalase in breast muscle, while it decreased (P < 0.05) catalase in the liver and malondialdehyde in breast muscle. Supplementation with Cr Prop significantly elevated (P < 0.05) the concentration of glutathione peroxidase in the liver and plasma, as well as the concentration of total superoxide dismutase in the liver, while it reduced (P < 0.05). the concentration of malondialdehyde in breast muscle. Supplementation with either amylase or Cr Prop significantly increased (P < 0.05) the levels of blood high-density lipoprotein cholesterol, immunoglobulin A, immunoglobulin G, and total protein, while significantly reducing (P < 0.05) triglyceride levels. Amylase supplementation alone notably enhanced villus height in both the jejunum and ileum. Furthermore, amylase or Cr Prop significantly upregulated (P < 0.05) the mRNA expression of Occludin and Claudin-1 in the Jejunum. The expression of Zona Occluden-1 was elevated by Cr Prop. However, the expression of Mucin 2 and Zona Occluden-2 remained unaffected. While amylase or Cr Prop supplementation alone could improve the performance and several healthy parameters in yellow-feathered broilers, no synergistic effect was observed.