Evaluating fermentation quality, in vitro digestibility and aerobic stability of a total mixed ration ensiled with different additives on Tibet plateau

Abstract

Objective: To investigate the improvement in utilization efficiency of total mixed ration (TMR) on Tibetan plateau, TMR were ensiled with different additives.Methods: A total of 150 experimental silos were prepared in a completely randomized design to evaluate the six treatments: i) control (without additive), ii) <i>Lactobacillus buchneri</i> (<i>L. buchneri</i>), iii) acetic acid, iv) propionic acid, v) 1,2-propanediol; and vi) 1-propanol. After 90 days of ensiling, silos were opened for fermentation quality and <i>in vitro</i> analysis, and then subjected to an aerobic stability test for 14 days.Results: Treating with <i>L. buchneri</i>, acetic acid, 1,2-propanediol and 1-propanol decreased propionic acid contents and yeast number, whereas increased (p<0.05) pH, acetic acid and ethanol contents in the fermented TMR. Despite increased dry matter (DM) loss in the TMRs treated with 1,2-propanediol and 1-pronanol, additives did not affect (p>0.05) all <i>in vitro</i> parameters including gas production at 24 h (GP₂₄), GP rate constant, potential GP, <i>in vitro</i> DM digestibility and <i>in vitro</i> neutral detergent fibre digestibility. All additives improved the aerobic stability of ensiled TMR to different extents. Specially, aerobic stability of the ensiled TMR were substantially improved by <i>L. buchneri</i>, acetic acid, 1,2-propanediol, and 1-propanol, indicated by stable pH and lactic acid content during the aerobic stability test.Conclusion: <i>L. buchneri</i>, acetic acid, 1,2-propanediol, and 1-propanol had no adverse effect on <i>in vitro</i> digestibility, while ensiling TMR with the additives produced more acetic acid and ethanol, subsequently resulting in improvement of aerobic stability. There is a potential for some fermentation boosting additives to enhance aerobic stability of fermented TMR on Tibetan plateau.