The effects of dietary nano-selenium (Nano-Se) supplementation on
broiler chickens fed diets without added selenium remain controversial.
This dose-response meta-analysis examined dietary Nano-Se effects on
broiler chickens. The meta-analysis results indicated that Nano-Se supplementation
up to 2 mg/kg linearly increased feed intake (p < 0.05).
Nano-Se supplementation improved both body weight gain and feed
conversion ratio (FCR, p < 0.05). Body weight gain peaked at approximately
0.35 mg/kg (increasing up to 0.90 mg/kg), while optimal FCR was
observed at 0.30 mg/kg (improving up to 0.80 mg/kg). Nano-Se addition
did not changed carcass, liver, or heart proportions (p > 0.05). However, a
negative linear association was observed between Nano-Se and abdominal
fat proportion at doses ranging from 0.50-1.80 (p < 0.05). Nano-Se
addition at the levels up to 0.40 mg/kg enhanced breast proportion (p <
0.05), with the greatest breast proportion observed at a Nano-Se level of
about 0.25 mg/kg. Blood triglyceride levels were unaffected by Nano-Se
supplementation (p > 0.05). However, supplemental Nano-Se reduced
blood cholesterol levels at doses of 0.10 and 0.20 mg/kg, while increasing
them at doses exceeding 0.40 mg/kg (p < 0.05). Nano-Se supplementation
enhanced blood GPx activity (p < 0.05), and the optimal Nano-Se
dose was determined to be 0.63 mg/kg. While the addition of Nano-Se
did not change the spleen index (p > 0.05), Nano-Se levels between 0.20
and 0.50 mg/kg boosted the antibody response to the Newcastle disease
vaccine (p < 0.05). However, Nano-Se administration did not impact ileal
villus height or crypt depth (p > 0.05). This study suggests that the
optimal dietary Nano-Se inclusion for broiler chickens may lies within
the range of 0.20–0.63 mg/kg. A critical knowledge gap exists regarding
the mechanisms by which Nano-Se is converted into selenoproteins,
necessitating further investigations.