To investigate the regulatory effects of exogenous ammonium sulfate on the silage quality and hydrogen cyanide （HCN） degradation of regrowth waxy sorghum [Sorghum bicolor （L.） Moench]， a 60-day silage experiment was conducted with three addition levels of ammonium sulfate （0%， 0.3%， and 0.5% of dry matter）. Fermentation characteristics， nutritional composition， feeding value， and HCN dynamics were continuously monitored. Principal component analysis （PCA） and redundancy analysis （RDA） were employed for comprehensive evaluation. The results showed that ammonium sulfate significantly improved both nutritional quality and silage safety. The 0.5% ammonium sulfate treatment increased crude protein by 12.3%， while neutral detergent fiber （NDF） and acid detergent fiber （ADF） decreased to 43.82% and 27.60%， respectively. Lactic and acetic acid concentrations increased by 35.7% and 28.4%， accelerating acidification （pH<4.2 within 7 days） and suppressing undesirable microorganisms. HCN degradation rate increased by 40% between 7 and 15 days， with final residual content below 170 mg·kg^-1 and a degradation rate of 53% after 60 days. Feeding performance was also enhanced， with relative feed value （RFV） and relative forage quality （RFQ） reaching 160 and 180， respectively. Overall， ammonium sulfate at 0.4%-0.6% of dry matter effectively improved silage fermentation， nutritional quality， and safety， meeting the standards for high-quality forage （RFV>145， HCN<200 mg·kg^-1） and providing a scientific basis for developing the “grain-forage dual-purpose” sorghum production model.

Ratooning sorghum  /  Ammonium sulfate  /  Silage quality  /  Hydrogen cyanide  /  feeding value