In vitro investigation of the effect of dairy propionibacteria on rumen pH, lactic acid and volatile fatty acids

Abstract

Ruminal acidosis is a prevalent disorder in ruminants such as dairy cows and feedlot beef cattle, caused primarily by the inclusion of a high percentage of readily fermentable concentrates in the diet. The disorder presents as an accumulation of lactic acid, a decrease of pH in the rumen and a subsequent imbalance of the rumen fermentation process with detrimental impacts on the animal's health and productivity. Dairy propionibacteria, a group of bacteria characterised by utilization of lactic acid as the favoured carbon source, with propionic acid produced as a by-product, were evaluated in this study as potential direct-fed microbials for use in controlling ruminal acidosis. Acidosis was simulated by introduction of high concentrations of lactic acid into rumen fluid samples and a multi-strain in vitro analysis was conducted, whereby changes in pH and lactic acid metabolism were compared in identical acidified rumen samples, following inoculation with various propionibacteria. This was followed by a study to evaluate the effect of bacterial inoculation dosage on acid metabolism. The results indicated that lactic acid levels in the rumen fluid were significantly reduced, and propionic acid and acetic acid concentrations both significantly increased, following addition of propionibacteria. Significant 'between strains' differences were observed, with Propionibacterium acidopropionici 341, Propionibacterium freudenreichii CSCC 2207, Propionibacterium jensenii NCFB 572 and P. jensenii 702 each producing more rapid reduction of lactic acid concentration than P. freudenreichii CSCC 2206, P. acidopropionici ATCC 25562 and Propionibacterium thoenii ATCC 4874. Furthermore, the efficacy of this application was dosage related, with the rates of reduction in lactic acid levels and production of propionic acid, both significantly greater for the higher (10 10 cfu mL-1) compared with lower (10 5 cfu mL-1) dosage inoculation. The results confirmed that the introduction of propionibacteria could promote more rapid reduction of lactic acid levels than would occur without their addition, demonstrating their potential in controlling ruminal acidosis.

Mixed Acid Fermentation of Carbohydrate-Rich Dairy Manure Hydrolysate

“…Caproiciproducens and Clostridium sensu stricto 12 are also significantly correlated with Acetobacter ( Supplementary Table S6 ), a genus characterized as an acetic acid producer ( Cleenwerck et al, 2002 ). Acidipropionibacterium, an apparent lactic utilizing bacteria ( Luo et al, 2017 ; Candry et al, 2020 ), correlated with Lactobacillus .…”

Propionic acid bacteria enhance ruminal feed degradation and reduce methane production in vitro

“…For the same reason, it seems unlikely that the increase in propionate observed when feeding P169 is produced by the strain P169 itself, since the recovery for this strain was 10 6 CFU per mL or lower (Peng et al, 2011). However, Luo et al (2017) showed that propionate can be formed by PAB at high rates and we cannot rule out that P169 could have produced propionate more rapidly in vivo than in vitro, as a result of the stimulation of natural microbial inhabitants of the rumen.…”

“…Previous studies found that PAB strains could increase rumen propionate levels (as a proportion of the total VFA) and lower levels of acetate in vivo (Stein et al, 2006;Raeth-Knight et al, 2007;Weiss et al, 2008) and in vitro (Akay & Dado, 2001;Alazzeh et al, 2013), suggesting that PAB could significantly contribute to rumen fermentation. Luo et al (2017) showed that PAB can degrade lactate in the rumen fluid in vitro. In experiments 1 and 2, the molar ratios of acetate to propionate in the controls were 4.0 and 4.6, respectively.…”

Survival of Lactobacillus plantarumU40 on the in vitro rumen fermentation quantified with real-time PCR

“…Higher lactic acid in rumen fluid trigger lactic acid utilizer growth. Some lactic acid utilizer such as Megasphaera elsdenii and Propionibacterium will consume lactic acid, leading to increased production of propionic acid (Seo et al, 2010;Luo et al, 2017). Increased propionic acid after inoculation of L. plantarum also reported by Weinberg et al (2003).…”