Persistence of subacute ruminal acidosis across first and second lactations in dairy cows based on reticular pH metrics and microbiota, and systemic health responses

Sep 24, 2025Journal of animal science

Ongoing mild rumen acid imbalance during first and second milk-producing periods in dairy cows linked to stomach acidity, gut microbes, and overall health

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Abstract

Seventeen lactating Holstein cows were observed to have no persistent severity from first to second lactation.

  • SARA severity type in the first lactation did not influence SARA indices in the second lactation.
  • All measured SARA indices increased with a higher concentrate diet but showed no significant differences after three weeks.
  • Liver enzyme levels increased during the high concentrate feeding period, regardless of SARA severity.
  • Cows with LOW SARA in the first lactation tended to have lower inflammatory markers.
  • Total volatile fatty acids (VFA) increased with the high concentrate diet, shifting in composition.
  • Microbiome diversity indices were primarily affected by first lactation SARA severity, particularly during high concentrate feeding.

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Key numbers

22.3 kg
Dry Matter Intake (DMI)
Average daily dry matter intake during the second lactation.
4.85 min
Reticular pH Duration
Duration below pH 6.0 in the first lactation.

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