biostudies-literatureUnknown10Shen JNational Natural Science Foundation of ChinaNational Key Research and Development Program of ChinaAmmonia is an important rumen internal environment indicator. In livestock production, feeding a large amount of non-protein nitrogen to ruminants will create high ammonia stress to the animals, which increases the risk of ammonia toxicity. However, the effects of ammonia toxicity on rumen microbiota and fermentation are still unknown. In this study, an <i>in vitro</i> rumen fermentation technique was used to investigate the effects of different concentrations of ammonia on rumen microbiota and fermentation. To achieve the four final total ammonia nitrogen (TAN) concentrations of 0, 8, 32, and 128 mmol/L, ammonium chloride (NH₄Cl) was added at 0, 42.8, 171.2, and 686.8 mg/100 mL, and urea was added at 0, 24, 96, and 384 mg/100 mL. Urea hydrolysis increased, while NH₄CFrontiers in veterinary science1163021https://www.ebi.ac.uk/biostudies/studies/S-EPMC10097989biostudies-literatureThe inhibition of high ammonia to <i>in vitro</i> rumen fermentation is pH dependent.PMC10097989Shen JZheng WYu ZXu YfalseThe inhibition of high ammonia to <i>in vitro</i> rumen fermentation is pH dependent.Ammonia is an important rumen internal environment indicator. In livestock production, feeding a large amount of non-protein nitrogen to ruminants will create high ammonia stress to the animals, which increases the risk of ammonia toxicity. However, the effects of ammonia toxicity on rumen microbiota and fermentation are still unknown. In this study, an <i>in vitro</i> rumen fermentation technique was used to investigate the effects of different concentrations of ammonia on rumen microbiota and fermentation. To achieve the four final total ammonia nitrogen (TAN) concentrations of 0, 8, 32, and 128 mmol/L, ammonium chloride (NH₄Cl) was added at 0, 42.8, 171.2, and 686.8 mg/100 mL, and urea was added at 0, 24, 96, and 384 mg/100 mL. Urea hydrolysis increased, while NH₄C2023-01-01T00:00:00Z20232026-05-17T03:11:58.589Z2024-10-19T01:47:06.775ZS-EPMC100979893706522510.3389/fvets.2023.1163021