Rumen Acidosis

Rumen acidosis in its subclinical form is common nutritional problem in dairy animals after parturition. Rumen pH declines below 5.9 and remains low for several hours. Two groups of dairy animals are at a risk of acidosis:

• Periparturient dairy animals (0-25 days postpartum) being adapted to high concentrate rations are at a risk.

• Dairy animals 45 to 125 day postpartum are at a risk of ration formulation error and feed delivery problems (lack of fibre level, excessive starch or feed selectivity)

Production of individual VFA shifts because acetate remains constant while propionate production increases resulting in less than 50% acetate and greater than 30% propionate with A:P ratios below 2.2:1. Milk fat test can be an indicator of rumen acidosis. Milk from individual dairy animals shows lower fat test and an increase in protein percentage.

Rumen acidosis can damage rumen papilae, alter sensitive laminae in the hoof, and reduce dry matter intake. If the hoof surface is not smooth or has ridges, ruminal acidosis occurred several weeks to several months ago.

Diagnostic Procedures:
Conduct a physical examination to rule out other causes of decreased DM intake. Evaluate the prepartum ration for rumen adaptability. Consider forage quality (mouldiness, caurseness, dustiness, sorting) which can limit forage intake.

Observe cud chewing and ruminating time (over 60% of dairy animals should be ruminating while resting). Check body condition to determine if animas are thin or heavy. Evaluate manure to see if it is loose or runny (one possible indication of fibre shortage).

Conduct rumenocentesis on six or more dairy animals per group (a technique to determine rumen pH and VFA concentration in intact animals), if indicated. Evaluate milk fat and milk protein percentages. Offer sodium bicarbonate and observe if condition improves. Provide hay ad libidum and watch which animals consume it.

Preventive measure:
Implement a transition diet for dry animals 14-21 days prepartum. Limit the rate of increasing concentrate feeding postpartum at 0.5 Kg per day. Avoid metabolic disorders in fresh dairy animals. Add or increase the amount of long forage in the ration. Add a buffer to the ration. Control forage and concentrate selectivity and variation.

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