How to Create a Low-DCAD Diet for Dry Cows?

A low-DCAD diet is an established method to avert milk fever by creating a slight metabolic acidosis that promotes calcium release. In this blog, we present a detailed guide for creating and modifying such a diet:

Step 1: Understand the DCAD Formula

The Dietary Cation-Anion Difference (DCAD) is determined using the following equation:

DCAD (mEq/kg DM)=(Na×43.5+K×25.6)?(Cl×28.2+S×62.5)

Where:

• Na = Sodium (% of DM)
• K = Potassium (% of DM)
• Cl = Chloride (% of DM)
• S = Sulphur (% of DM)

The objective for prepartum cows is to maintain a DCAD within the range of -10 to -15 mEq/kg DM.

Step 2: Examine Feed Components

Acquire a feed analysis to assess the concentrations of sodium, potassium, chloride, and sulphur in forage and concentrate components. Concentrate on:

• Potassium (K): Refrain from feeding on forages rich in potassium such as alfalfa or verdant grass. Target K to be less than 1.5% of the diet.
• Sodium (Na): Keep levels moderate (0.10–0.15%).
• Chloride (Cl) and Sulphur (S): Utilize anionic salts to boost these anions (e.g., calcium chloride, magnesium sulphate).

Step 3: Modify the Diet

• Incorporate Forages Low in Potassium: Grass hay or corn silage serves as an excellent primary forage.
• Restrict alfalfa hay and silages that are high in potassium.
• Incorporate Anionic Salts such as Calcium chloride (CaCl?), Magnesium sulphate (MgSO?), Ammonium chloride (NH?Cl), and Calcium sulphate (CaSO?). Begin with limited quantities and gradually raise them to prevent feed rejection.
• Energy and Fiber Balance: Ensure suitable energy density and fiber content (e.g., NDF around 30–35%).
• Add Magnesium: Incorporate magnesium oxide (MgO) to guarantee 0.4–0.45% Mg in the feed.

Step 4: Monitor Urine pH: After formulating the diet, monitor urine pH to assess the DCAD’s effectiveness:

• Target urine pH for Holstein cows: 6.0–6.5
• Target urine pH for Jersey cows: 5.5–6.0

Test urine samples 48–72 hours after starting the diet.

Step 5: Example Diet Formulation:?

For a dry cow diet of 12 kg dry matter intake (DMI):

Forage base:

• Grass hay (9 kg DM, low K, low Ca)
• Grain/concentrate:

?? Corn grain (1.5 kg DM)

?? Soybean meal (0.5 kg DM)

Minerals:

• Calcium chloride: 50 g
• Magnesium sulphate: 30 g
• Di-calcium phosphate: 20 g

Add salt (sodium chloride) or ammonium chloride as needed to fine-tune DCAD.

Conclusion:

Research shows that creating a low-DCAD diet helps prevent milk fever while ensuring smooth calving transitions. The health of cows and their calcium mobilization can be enhanced by dairy farmers who select forages with low potassium, integrate anionic salts into diets and monitor urine pH levels.

Successful results depend on maintaining proper nutrient balance together with regular tracking and small dietary modifications. A properly implemented low-DCAD diet prevents metabolic issues while simultaneously optimizing lactation results and herd productivity. Through diligent planning and ongoing monitoring you can boost dairy business profits while improving dry cow health.