Dissolved hydrogen (dH) influences the pathways of VFA production and is a precursor of methane formation in the rumen. Measurements of dH in rumen fluid taken at the same time as measuring other rumen fermentation end products would improve our quantitative understanding of the role of dH as a controller of rumen fermentation. Sample collections though a rumen cannula and using oral stomach tubing were compared for measurements of dissolved gases and fermentation end products in the rumen fluid of 4 ruminally cannulated dairy cows fed a total mixed ration of corn silage and concentrate. Rumen fluid was collected at 0, 2.5, and 6 h after morning feeding through the cannula from cranial dorsal rumen, cranial ventral rumen, central rumen, caudal dorsal rumen, and caudal ventral rumen and in parallel by oral stomach tubing at 2 insertion depths of 180 cm (sampling the central rumen) and 200 cm (sampling the caudal dorsal rumen). The cranial dorsal rumen had the greatest pH and smallest VFA concentration among 5 sites sampled. Samples collected by oral stomach tubing had greater ( < 0.001) rumen pH and less ( < 0.001) dissolved methane (dCH) and lower VFA concentration than that collected through rumen cannula. The dH concentrations were positively correlated ( > 0.8) in rumen samples collected by the 2 sampling techniques, with a concordance correlation coefficient larger than 0.8 and scale shift being about 0.1 away from unity. The variations in the measurement of dH, dCH, pH, and VFA in samples collected by oral stomach tubing are most likely the result of saliva contamination. The time of sampling relative to feeding had significant influence ( < 0.01) on dissolved gases and fermentation end products, with the greatest concentrations of dH, dCH, and VFA measured 2.5 h after morning feeding. The dH was correlated positively ( > 0.58) with dCH and negatively ( < -0.65) with the estimated net H production relative to the amount of VFA produced. This indicated that greater dH enhanced rumen CH production and also led to fermentation pathways that produce less H, such as enhanced propionate and butyrate production. In summary, oral stomach tubing could be a feasible method to measure ruminal dH in intact animals, but caution should be taken to minimize saliva contamination. Measurements made using both techniques yield similar conclusions for the effects of dH on fermentation pathways and CH generation.
Is phytic acid (IP6) an undesirable constituent for vegetables and foods? This question is getting harder to answer. Phytic acid contributes to mineral/protein deficiency, but also brings about potential physiological benefits. Both the positive and negative effects boil down to the interactions among IP6, metal ions, and biopolymers. In the wake of the booming market of plant‐based foods, an unbiased understanding of these interactions and their impacts on the foods themselves is a necessity to the smart control and utilization of plant‐sourced phytates. This overview presents updated knowledge of IP6‐related interactions, with a strong focus on their contributions to food functionality, processability, and safety.
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