Looking back can allow us to look ahead. Three management practices used to treat fresh cows are summarized below.

Case 1 Dairy farmers report drenching or offering free choice five to fifteen gallons of warm water containing calcium propionate, yeast culture, and electrolytes immediately after calving result in more cows cleaning, few displaced abomasums, and healthy cows.

Case 2 Administered a tube or gel product containing 50 to 55 grams of calcium to cows immediately after calving may turn "dull-looking or sluggish cows" into alert and healthy cows.

Case 3 Registered breeders indicate cows with three or more calvings or cows that experienced calving problems during earlier lactations are administered intravenous infusions of calcium solution to avoid metabolic disorders and minimize milk fever.

All three examples share one common factor; adding supplemental calcium at calving can improve health and performance. Over 40 percent of dairy cows have one or more adverse health events during the transition period (such as retained placenta, displaced abomasums, milk fever, metritis, and/or ketosis). Data from Minnesota cows on DHI test indicated that 24 percent of cows culled left the herd during the first 60 days after calving. These "broken cows" or early culled cows may be traced back to difficulty during the transition period. Many health disorders that occur in early lactation can be linked to the effects of hypocalcemia (low blood calcium levels).

Milk fever affects 3 to 6 percent of the dairy cows in the US. A growing body of research indicates that up to 60 percent or more of dairy cows in high producing herds can experience hypocalcemia. This high level of hypocalcemia can occur in herds that experience few clinical cases of milk fever. Subclinical hypocalcemia are cows with low blood calcium (< 8 mg/dl), but not low enough to cause the cow to go down with clinical milk fever (< 5.0 mg/dl). Hypocalcemia has been linked to many postpartum disorders. Cows with this disorder have sluggish early lactation milk production, low dry matter intake, and higher incidences of displaced abomasum, retained placenta, ketosis, mastitis, and other fresh cow disorders. In a national US survey conducted in 2002 on over 1400 dairy cows, researchers determined that 25, 42 and 53 percent of 1st, 2nd and 3rd lactation and over cows, respectively, had blood calcium levels of below 8 mg/dl.


The close-up ration is the most important ration on the dairy. In fresh dairy cows, low blood calcium levels have been attributed to the alkalizing (cation) effect in the pre-fresh ration. Feeding a diet properly balanced for dietary cation anion difference (DCAD) can prevent hypocalcemia by causing the cow's blood to become slightly acidic. This slight metabolic acidosis helps parathyroid hormone (PTH), the main hormone that controls the blood level of calcium, function properly. If a herd is having metabolic problems early postpartum such as milk fever, displaced abomasums, and/or retained placenta, DCAD levels of the ration may be positive.

To reduce the incidence of milk fever, close up rations are being formulated for low potassium and low calcium levels. These rations can be effective in the prevention of clinical milk fever. Feeding corn silage as the main forage source and selecting low potassium hay can accomplish this goal. However, these diets still can have an alkalizing effect leading to the possibility of hypocalcemia.

In a Michigan State University study, seven out eight cows fed a diet with a positive DCAD (+150 meq/kg) had subclinical hypocalcemia after freshening and four out of eight cows fed a diet of 0 DCAD experienced hypocalcemia with three of these being clinical. No cases of hypocalcemia were observed in the cows fed the negative DCAD diet (-150 meq/kg). Additionally, the cows on the low DCAD diet had lower blood NEFA levels than those on the other diets. This improvement may be attributed to the fact the cows fed the negative DCAD diet did not experience as great of a decline in prepartum DMI as did those cows fed the other diets.

Benefits of Chloride
Anionic salts are those salts that contain more strong anions (negative minerals) than cations (positive minerals). These anionic salts can include ammonium chloride, calcium chloride, magnesium chloride, calcium sulfate and magnesium sulfate. The chloride salts are more effective in reducing urine pH than the sulfate salts (Table1). Unfortunately, the anionic salts may also deliver a cation to the ration along with the anions. This cation works in raising pH making the anionic salts less effective at reducing pH.

Table 1. Impact of various compounds (fed at two equivalents of each feed source) to reduce urine pH fed (indication of effectiveness of the product to cause metabolic acidosis).

An effective range of urine pH, to minimize postpartum disease, should be the goal of the close-up DCAD program. To achieve a urine pH range of 6.0 to 7.0, the anionic source needs to be adjusted to the correct level.

Hydrochloric acid is a palatable source of chloride. The anionic salts are bitter and can cause a reduction in dry matter intake if fed at too high a level or not masked completely with silage and grain. Unlike the bitter tasting anionic salts, hydrochloric treated products (such as SoyChlor, Biochor, and NutraChlor, trade names of commercially available compounds) are more palatable and preferred by cows. Reports from the field suggest dry matter intakes of 28 pounds or higher can occur when feeding this type of anionic products.

The 2001 Dairy NRC recommends lower protein diets for close up dairy cows (12 percent) compared to earlier recommendations for close-up mature cows. Energy must be used to detoxify the extra ammonia impacting liver function. The negative effects are probably worse for sources of non-protein nitrogen (soluble protein sources). Herds prone to fatty livers should not feed diets containing large amounts of soluble protein and NPN. An all-natural protein feed treated with hydrochloric acid can effective a chloride alternative to the high NPN anionic sources (such as ammonium chloride). Heifers require more crude protein because they are still growing (14 percent).

New York workers report milk fever costs a dairy an average of $334 per case. The other postpartum diseases linked to hypocalcemia and their costs are listed in Table 2.

Table 2. Relationship of metabolic disorders and economic loses (dollar loss, culling, milk, and reproduction).

Avoiding the diseases associated with hypocalcemia and keeping cows in the herd longer also adds to the bottom line. In herds where clinical milk fever and ketosis were not major problems, an additional 700 to 1,000 pounds of milk can be gained by avoiding subclinical hypocalcemia returning three dollars for each dollar spent on anionic products. Table 3 illustrates the potential economic impact of feeding an anionic product at various herd sizes and milk prices. Values in Table 3 were based on herds that had five percent milk fever, a reduction from 50 to 5 percent hypocalcemia, and 700 pounds more milk due to feeding an effective anionic product.

Table 3. Potential economic benefits of feeding an anionic product reducing milk fever and hypocalcemia while increasing milk yield.

Source: Mike Hutjens, University of Illinois Extension Dairy Specialist