Effects of using different roughages in the total mixed ration inoculated with or without coculture of Lactobacillus acidophilus and Bacillus subtilis on in vitro rumen fermentation and microbial population

Abstract

Objective: This study aimed to determine the effects of different roughages in total mixed ration (TMR) inoculated with or without coculture of <i>Lactobacillus acidophilus</i> (<i>L. acidophilus</i>) and <i>Bacillus subtilis</i> (<i>B. subtilis</i>) on <i>in vitro</i> rumen fermentation and microbial population.Methods: Three TMRs formulations composed of different forages were used and each TMR was grouped into two treatments: non-fermented TMR and fermented TMR (F-TMR) (inoculated with coculture of <i>L. acidophilus</i> and <i>B. subtilis</i>). After fermentation, the fermentation, chemical and microbial profile of the TMRs were determined. The treatments were used for <i>in vitro</i> rumen fermentation to determine total gas production, pH, ammonianitrogen (NH₃-N), and volatile fatty acids (VFA). Microbial populations were determined by quantitative real-time polymerase chain reaction (PCR). All data were analyzed as a 3×2 factorial arrangement design using the MIXED procedure of Statistical Analysis Systems.Results: Changes in the fermentation (pH, lactate, acetate, propionate, and NH₃-N) and chemical composition (moisture, crude protein, crude fiber, and ash) were observed. For <i>in vitro</i> rumen fermentation, lower rumen pH, higher acetate, propionate, and total VFA content were observed in the F-TMR group after 24 h incubation (p<0.05). F-TMR group had higher acetate concentration compared with the non-fermented group. Total VFA was highest (p<0.05) in F-TMR containing combined forage of domestic and imported source (F-CF) and F-TMR containing Italian ryegrass silage and corn silage (F-IRS-CS) than that of TMR diet containing oat, timothy, and alfalfa hay. The microbial population was not affected by the different TMR diets.Conclusion: The use of Italian ryegrass silage and corn silage, as well as the inoculation of coculture of <i>L. acidophilus</i> and <i>B. subtilis</i>, in the TMR caused changes in the pH, lactate and acetate concentrations, and chemical composition of experimental diets. In addition, F-TMR composed with Italian ryegrass silage and corn silage altered ruminal pH and VFA concentrations during <i>in vitro</i> rumen fermentation experiment.