Calcium Propionate Supplementation Mitigated Adverse Effects of Incubation Temperature Shift on In Vitro Fermentation by Modulating Microbial Composition

The ingestion of cold water in winter results fluctuating decreases rumen temperature, impacting fermentation function and methane production. This study aimed to investigate the impact calcium propionate (CaP) on characteristics, production, microbial microbiome under different vitro incubation temperatures. A 2 × factorial experiment was conducted over 72 h, with or without 2.5% CaP (dry matter [DM] basis) substrate a constant temperature (39 °C, CIT) shifting temperatures (12 cycles total, each cycle consisting 4 h at 39 °C followed by immediate transfer 30 for ITS). showed that ITS inhibited gas concentration 12 (p < 0.05), reduced ammonium nitrogen (−14.25%), (−16.14%), butyrate (−12.67%), total volatile fatty acid (−8.50%) more than CIT groups 0.05). addition significantly increased production (+4.84%), asymptotic (+5.08%, per 0.2 g DM substrate), (+18.05%), valerate (+9.45%) 0.05) compared CaP-free groups, while it had no observable effect methane. Furthermore, yielded significant increase relative abundance Bacteroides Under condition, Methanomicrobiales decreased positively correlated (r = 0.47, p Additionally, Prevotella_UCG_003 which negatively 0.45, Overall, our suggests can alleviate adverse effects parameters regulating composition sustaining reduction