Inducing subacute ruminal acidosis in lactating dairy cows

Area of Science:

• Animal Science
• Ruminant Nutrition
• Dairy Cattle Production

Background:

• Subacute ruminal acidosis (SARA) is a metabolic disorder affecting dairy cows, impacting ruminal pH and potentially production.
• Understanding the effectiveness of SARA induction protocols is crucial for research on its effects on dairy cattle.

Purpose of the Study:

• To evaluate the effectiveness of a specific SARA induction protocol in lactating dairy cows.
• To assess the impact of induced SARA on ruminal pH, dry matter intake, milk yield, and milk composition.

Main Methods:

• Lactating dairy cows (n=13) were subjected to a 4-period protocol: baseline, restricted feeding, challenge feeding (pellets), and recovery.
• Continuous ruminal pH monitoring, daily dry matter intake, and milk yield recordings were performed.
• Milk composition was analyzed in a subset of cows (n=9).

Main Results:

• The SARA induction protocol significantly lowered mean ruminal pH (5.85) and nadir pH (5.13) during the challenge period compared to baseline (6.31 and 5.76).
• Hours below pH 5.6 and area below pH 5.6 increased substantially during the challenge period.
• Milk yield decreased significantly (31.7 kg/d) during the challenge and remained depressed during recovery (31.3 kg/d), while dry matter intake was unaffected. Milk fat percentage was not depressed, but fat yield decreased during recovery.

Conclusions:

• The experimental protocol effectively induced subacute ruminal acidosis in lactating dairy cows without causing acute acidosis symptoms.
• Induced SARA led to a substantial reduction in milk yield that persisted beyond the 2-day recovery period.
• Further research is needed to understand long-term production impacts and mitigation strategies for SARA in dairy herds.