Effects of encapsulation and combining probiotics with different nitrate forms on methane emission and in vitro rumen fermentation characteristics

Abstract

This study aimed to evaluate the effects of encapsulation and combining probiotics with different nitrate forms on methane emission and the in vitro fermentation process of ruminants. Sodium nitrate (NaNO3) and nitric acid (HNO3) were used as nitrate forms, while lactic acid bacteria Lactiplantibacillus plantarum TSD-10 was used as a probiotic source. Twelve different treatments with four replicates were allocated in the factorial block design (2 × 2 × 3). During each replicate, the test was conducted individually in a different week so that each block could be considered separately. Data analysis followed the analysis of variance (ANOVA) and then continued with the Duncan multiple range test. After encapsulation, significant increases (p < 0.05) in gas production, gas kinetics, total volatile fatty acids (TVFAs), and production of propionic acid were observed. In addition, encapsulation significantly decreased (p < 0.05) the pH, ammonia concentration (NH3), nutrient digestibility, and the ratio of acetic to propionic acid (p < 0.05). The addition of combined encapsulated probiotics and encapsulated nitrate significantly increased (p < 0.05) gas production, maximum gas production, TVFAs, and the molar portion of propionic acid, and significantly decreased (p < 0.05) enteric methane emission, acetic acid, ammonia concentration, pH, and nutrient digestibility. The addition of sodium nitrate significantly increased (p < 0.05) the concentration of TVFAs and acetic acid, while nitric acid significantly increased (p < 0.05) the gas production rate. However, there was no significant effect due to combining unencapsulated probiotics with unencapsulated nitrate forms on the rumen fermentation process. There was a significant interaction (p < 0.05) between encapsulation probiotics and nitrate on ammonia concentration. In conclusion, combining encapsulated probiotics with encapsulated nitrate is an alternative method for enhancing the fermentation process and mitigating enteric methane emission in ruminants.