The efficacy and safety of a novel Subtilisin protease from a Bacillus sp. produced in Bacillus licheniformis was investigated in broiler chickens, and a range of toxicological tests, respectively. The B. licheniformis production strain culture supernatant was not found cytotoxic in a Vero cell assay. Subtilisin was non-mutagenic and non-clastogenic in in-vitro tests, and did not exhibit irritating potential to the eye or skin in ex-vivo/in-vitro models. Oral administration of Subtilisin to rats did not cause any adverse effects in a 13-week sub-chronic toxicity study. In addition, a 35-day dose response broiler performance trial conducted with Subtilisin (30,000 and 60,000 NFP/kg diet), showed a significant linear improvement in both body weight gain and feed conversion ratio up to 35 days of protease supplementation. In conclusion, there are no safety concerns using this novel Subtilisin as a feed additive, and the protease is efficient in improving broiler growth performance, making it a good candidate for use as a feed additive.
Keywords: Bacillus licheniformis; Broiler chickens; Feed additive; Safety; Subtilisin; Toxicity.
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