Zang et al., 2018. J. Appl. Poult. Res., 27 (4): 609‑615

Earthworms have been studied as a feed additive and animal protein source for poultry for many years. The interest in earthworm use for manure management has greatly increased over the past few decades. However, it is unknown whether earthworm powder in the diet poses a potential heavy metal risk for broiler pullets. This study was conducted to investigate the safety of adding earthworm powder in the diets of broiler pullets. A total of 240 Ningdu Yellow broiler pullets were randomly assigned to 4 groups receiving diets supplemented with 0%, 1%, 3%, or 5% earthworm powder for 30 d. Feed conversion ratios were improved by 12.64% and 22.45%, when 3% and 5% earthworm powder, respectively, were added (P = 0.02). Supplementing the diet with 5% earthworm powder had no negative effects on the growth of pullets, and increased antioxidant enzyme (superoxide dismutase, catalase, and glutathione peroxidase) activities in the liver (P < 0.05). The liver contained higher levels of heavy metals than did the thigh and chest muscles. All heavy metal residues in the thigh and chest muscles, as well as the liver, were below China's permissible limits. These results suggest that dietary supplementation with 1%-5% earthworm powder is safe for broiler pullets.