Short communication: Comparison of pH, volatile fatty acids, and microbiome of rumen samples from preweaned calves obtained via cannula or stomach tube

Abstract

The objective of this study was to compare rumen samples from young dairy calves obtained via a stomach tube (ST) or a ruminal cannula (RC). Five male Holstein calves (46±4.0 kg of body weight and 11±4.9 d of age) were ruminally cannulated at 15 d of age. Calves received 4 L/d of a commercial milk replacer (25% crude protein and 19.2% fat) at 12.5% dry matter, and were provided concentrate and chopped oats hay ad libitum throughout the study (56 d). In total, 29 paired rumen samples were obtained weekly throughout the study in most of the calves by each extraction method. These samples were used to determine pH and volatile fatty acids (VFA) concentration, and to quantify Prevotella ruminicola and Streptococcus bovis by quantitative PCR. Furthermore, a denaturing gradient gel electrophoresis was performed on rumen samples harvested during wk 8 of the study to determine the degree of similarity between rumen bacteria communities. Rumen pH was 0.30 units greater in ST compared with RC samples. Furthermore, total VFA concentrations were greater in RC than in ST samples. However, when analyzing the proportion of each VFA by ANOVA, no differences were found between the sampling methods. The quantification of S. bovis and P. ruminicola was similar in both extraction methods, and values obtained using different methods were highly correlated (R(2)=0.89 and 0.98 for S. bovis and P. ruminicola, respectively). Fingerprinting analysis showed similar bacteria band profiles between samples obtained from the same calves using different extraction methods. In conclusion, when comparing rumen parameters obtained using different sampling techniques, it is recommended that VFA profiles be used rather than total VFA concentrations, as total VFA concentrations are more affected by the method of collection. Furthermore, although comparisons of pH across studies should be avoided when samples are not obtained using the same sampling method, the comparison of fingerprinting of a bacteria community or a specific rumen bacterium is valid.

Effects of Sampling Techniques and Sites on Rumen Microbiome and Fermentation Parameters in Hanwoo Steers

“…Overall, we found that there was no impact of different sampling techniques and sampling sites on the composition of the rumen microbiome in the collected samples based on next-generation sequencing. This observation is similar to previous studies on rumen microbiomes in calves, sheep, goats, and beef cattle using the traditional PCR-DGGE method [3][4][5] and a recent study on rumen microbiomes in Holstein and Jersey cattle using next-generation sequencing [6]. Therefore, the stomach tube can be a feasible alternative method to collect representative samples of the rumen digesta from Hanwoo steers, which will contribute to investigating the composition of the rumen microbiome by increasing the number of animals that can be sampled.…”

“…Several studies have shown that the stomach tube is a feasible alternative to rumen cannulation in sheep, goats, calves, and cattle based on comparison of the composition of rumen microbiomes using the traditional polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) method [3][4][5]. In addition, Paz et al [6] showed that the rumen microbiome was similar between stomach…”

“…Keywords: 16S rRNA gene amplicon sequencing, fermentation parameters, rumen microbiome, stomach tube, cannulation S S tube and cannulization samples in Holstein and Jersey cattle using next-generation sequencing. Moreover, some studies showed similar rumen fermentation parameters such as pH, volatile fatty acids (VFA), and ammonia between the two sampling techniques [3][4][5]7], whereas others demonstrated differences [8,9]. Paz et al [6] indicated that discarding the first 200 ml of the rumen fluid could help to minimize saliva contamination that can influence the fermentation parameters.…”

Design, implementation and interpretation of in vitro batch culture experiments to assess enteric methane mitigation in ruminants—a review

“…Access to surgically-modified animals is not universal, and therefore less invasive techniques, such as oral stomach probing, have been used as an alternative. In the relatively few studies that have compared sampling through the rumen cannula or by stomach probing, differences in fermentation profile and microbiota have been reported in some (e.g., Geishauser and Gitzel, 1996;Duffield et al, 2004) but not all cases (e.g., Lodge-Ivey et al, 2009;Shen et al, 2012;Terré et al, 2013). Part of the discrepancy between studies may reflect differences in the procedures used to avoid salivary dilution and contamination, the type of samples collected and rumen sampling site.…”

Ruminal Bacterial Community Composition in Dairy Cows Is Dynamic over the Course of Two Lactations and Correlates with Feed Efficiency

“…These symbionts are capable of fermenting host-indigestible feed into nutrient sources usable by the host, such as volatile fatty acids (1,2). Ruminants are born without a functional rumen and are thought to acquire their digestive microbes from the environment as the rumen develops (3)(4)(5)(6). Although the means by which ruminants acquire this ruminal microbial community remains unclear, the membership and stability of the ruminal community can have a direct and measurable impact on host function and health (7).…”