Sales anionicas en bovinos de leche

of all mature cows are estimated to be hypocalcemic at calving. Drops in plasma calcium pools cause hypocalcemia. Calcium is vital to smooth muscle contraction. Therefore, postpartum subclinical hypocalcemia affects the reproductive tract’s involution process, and gut motility. Normal blood calcium is 8 to 12 milligrams per decaliter (mg/dl). Blood calcium reduced to 7.5 or 5 mg/dl can lowerabomasal motility by 30 and 70 percent, respectively. Reduced abomasal motility from low blood calcium lowers feed intake and displaces the abomasum. Traditionally, hypocalcemia was thought to be caused by improper dietary calcium levels in the dry period. High calcium intakes in the dry period (more than 70 grams of calcium per day) were thought to suppress the cow’s ability to use bone stores atcalving, thereby inducing milk fever. However, recent research suggests that potassium may play a significant, if not primary, role in subclinical and clinical hypocalcemia. If prepartum diets are high in calcium or potassium, consider an anionic salt program in the close-up dry-cow ration. Anionic salts are minerals with a high proportion of anions. Anions are negatively charged; cations

arepositively charged. Living tissue maintains a balance of anions and cations to achieve neutrality. Thus, the balance of anions and cations in a feed should be near neutral. However, certain cations and anions greatly affect the body’s metabolic processes. In particular, the cations sodium and potassium and the anions chloride and sulfur are considered to greatly influence the acid-base status in thebody. The dietary cation-anion difference (DCAD) concept quantifies the major cations and anions in diets. A negative DCAD diet contains more equivalents of anions than cations; a zero DCAD diet indicates balanced equivalents; and a positive DCAD diet contains more cation equivalents. Research recommends a DCAD of 10 to 15 milliequivalents per 100 grams of dry matter for closeup dry cows. Tocalculate DCAD in milliequivalents per 100-gram ration of dry matter, use the following formula: [(% sodium/0.023) + (% potassium/0.039)] — [(% chloride/0.0355) + (% sulfur/0.016)] A ration using typical forages and concentrates generally has a positive DCAD. Adding anionic salts (magnesium sulfate, calcium sulfate, ammonium

Using anionic salts to manipulate DCAD
Keep these guidelines in mind whenusing anionic salts to manipulate the dietary cation-anion difference (DCAD): Know the macromineral (potassium, calcium, sulfur, chloride) content of all feeds in the diet. Wet chemistry techniques are recommended for accurate mineral analysis. s Calculate the DCAD of the diet (see formula above). Manipulate the initial DCAD by optimizing low-potassium forages; the lower the initial DCAD, the lessanionic salts needed to achieve desired DCAD balance. Many forages have high potassium contents (2.0 to 4.0 percent of DM). Consider designating certain fields for dry cow forage production and apply no manure to these fields. s Supplement with calcium sulfate, ammonium sulfate, magnesium sulfate or a combination until total dietary sulfur reaches 0.4 percent. s Add calcium chloride, magnesiumchloride, ammonium chloride or a combination until the DCAD is 10 to 15 milli-equivalents per 100 grams of dry matter, following these guidelines: Set dietary magnesium at 0.4 percent. Raise dietary chloride to 0.5 to 0.6 percent; these levels appear to affect dry matter intake little. Dietary chlorine levels above 0.8 percent may reduce feed intake.
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When using ammonium salts, check nonproteinnitrogen levels to avoid ammonia toxicity. Minimize ammonium salt use in diets with more than 70 to 75 percent of total protein in the degradable form. Raise dietary calcium to 1.5 to 1.8 percent of dry matter (dietary supplementation between 150 and 200 grams calcium per day). Set dietary phosphorus at about 0.4 percent (dietary supply between 35 and 50 grams of phosphorus per day). s Monitor...