Subacute ruminal acidosis phenotypes in periparturient dairy cows differ in ruminal and salivary bacteria and in the in vitro fermentative activity of their ruminal microbiota

Abstract

Both ruminal microbial structure and functionality might play a role in inter-individual variation in susceptibility for subacute rumen acidosis (SARA) observed in dairy cows. The aims of this study were to determine whether differences between cows with distinct SARA susceptibility were reflected in distinct (1) ruminal microbial communities, (2) salivary bacterial communities, and (3) fermentative capacity of ruminal microbiota assessed in vitro. To test this hypothesis, rumen samples were collected via an esophageal tube on 21 d postpartum from 38 multiparous Holstein cows, which were classified into 4 groups differing in median and mean time of reticular pH below 6 as well as area under the curve of pH below 6.0. During the 21 d postpartum, all cows within a group fulfilled following criteria: susceptible (S, n = 10; mean or median ≥180 min/d), moderately susceptible (MS, n = 7; 60 min/d < mean time of pH below 6 < 180 min/d, and median time of pH below 6 <180 min/d), moderately unsusceptible (MU, n = 11; 10 min/d < mean < 60 min/d, and median time of pH below 6 ≤30 min/d), or unsusceptible (U, n = 10; median = 0 min/d, and mean <10 min/d). Groups did not differ in total daily dry matter intake nor in total, roughage, or concentrate intake during daily 6-h time intervals. Rumen bacterial α-diversity did not differ among groups, but β-diversity varied and bacterial 16S rRNA gene copy numbers were lower in S compared with U cows. The relative abundance of genera Streptococcus, Sharpea, Prevotellaceae_YAB2003, Succinivibrionaceae_UCG-001, Ruminococcus, and Ruminococcaceae_UCG-001 were higher in S compared with U cows. In contrast, Lachnospiraceae_ND3007 and Oscillospiraceae_V9D2013 were more abundant in U cows. Although pH-associated, inter-animal differences were also observed in the salivary bacteria, common differences in ruminal and salivary bacterial genera were limited. The functionality of the rumen microbiota was evaluated in vitro through exposure of the microbial inoculum of S and U cows to an anaerobic buffer at pH 5.8 and 6.8, in the presence of sterile supernatant of their own and of dry cows' rumen fluid (2 × 2 design). Generally, the S inoculum produced more volatile fatty acids, except at low pH with dry cows' supernatant, where volatile fatty acid production was completely impaired and lactate accumulation was highest. Compared with the microbes of U cows, microbes of S cows showed less fermentative activity in situations with 2 stress factors (low pH and an unfamiliar environment, i.e., rumen fluid supernatant of dry cows).

Elucidating the factors and consequences of the severity of rumen acidosis in first-lactation Holstein cows during transition and early lactation

“…Likewise, using the more commonly applied SARA definition of ruminal pH < 5.8 for > 330 min/d ( Zebeli et al, 2008 ), HIGH cows had SARA for 77% of the experimental period, while LOW cows only in maximum 7% of the experimental days. Varying SARA severities have also been identified in multiparous Holstein cows ( Yang et al, 2022 ), showing that this is a common phenomenon in dairy cattle. However, the SARA intervals of cows with high severity were substantially longer in our study than by Yang et al (2022) , which may be due to the fact that primiparous cows are more prone to SARA than multiparous cows ( Stauder et al, 2020 ) and emphasizes the cows’ vulnerability during the first lactation.…”

“…Varying SARA severities have also been identified in multiparous Holstein cows ( Yang et al, 2022 ), showing that this is a common phenomenon in dairy cattle. However, the SARA intervals of cows with high severity were substantially longer in our study than by Yang et al (2022) , which may be due to the fact that primiparous cows are more prone to SARA than multiparous cows ( Stauder et al, 2020 ) and emphasizes the cows’ vulnerability during the first lactation. Unexpectedly, cows within each group experienced SARA with almost similar duration throughout the complete experiment, indicating to be rather independent of moderate- or high-grain feeding and feed intake level.…”

“…Despite their generally higher risk to develop SARA, the severity in first-lactation cows has repeatedly been shown to largely vary between individuals, even when receiving the same diet ( Humer et al, 2015 ; Nasrollahi et al, 2017 ; Khiaosa-Ard et al, 2018 ). Yet, the causes of different SARA severity remain scarcely understood and it is unclear whether rumen fermentation factors, animal behavior and metabolism or other mechanisms are the root cause ( Nasrollahi et al, 2017 ; Khiaosa-Ard et al, 2018 ; Yang et al, 2022 ). In addition, the impact of SARA severity for cow health and behavior are not yet clear.…”

Relationship between Reticulorumen Parameters Measured in Real Time and Methane Emission and Heat Stress Risk in Dairy Cows

“…It was possible to monitor real-time parameters such as pH, temperature of reticulorumen content (TRR), and cow activity by smaXtec boluses (smaXtec animal care technology ® ) [ 24 , 25 ]. Antennas (smaXtec animal care technology ® ) were used to collect the data.…”

Susceptibility of dairy cows to subacute ruminal acidosis is reflected in both prepartum and postpartum bacteria as well as odd- and branched-chain fatty acids in feces

“…As such, we aimed to determine if fecal bacterial communities postpartum and prepartum contribute to identifying postpartum SARA susceptibility. The fecal samples of this study were obtained from an experiment with 38 dairy cows, which showed inter-animal variation in SARA susceptibility [23].…”