Variation in dietary cation-anion differences (DCAD) of feed ingredients in relation to milk fever disease in dairy cattle

摘要

Milk fever is an important disease that affect lactating cow due to the shortage of calcium circulation after parturition. Incidence of milk fever can be minimized by changing diet acidity/alkalinity before parturition to enhance Ca release of bone, and minimizing it excretion through several regulatory mechanisms. However, cow’s regulatory mechanisms are inadequate in its ability to satisfy the increased metabolic requirement of calcium. Many formulas have been suggested in literature for calculating Dietary Cation-Anion Differences (DCAD) in attempts to acidify diets to minimize the incidence of milk fever. Thus, selection of feed ingredients, and used formula (DCAD below 0 mEq/kg) are important when formulating diet to reach appropriate acidification of the cows’ blood. The aim of current study is to characterize and to measure DCAD of different feed ingredients (Listed in: National Research Council (NRC, 2001)) using the most used equations reported in the literature which are highly correlated with the incidence of milk fever. Tabulated DCAD values showed that the ability of most forages to cause acidification of the cow is not possible and few feed ingredients possessed mild-strong acidic effect. However, using ingredients with acidic effect have nutritional and economic limitations especially in dairy diets. This screening study showed that mostly used feed ingredients in Jordan possess alkaline effect. The magnitude of DCAD 1 ((Na + + K + ) + (Cl - )), DCAD 2 ((Na + + K + ) + (Cl - + S -2 )) and DCAD 3 ((Na + + K + ) + (Cl - + 0.6S -2 )) of different feed ingredients mainly used in Jordan ranged from 93.5 - 592.7 mEq/kg, 31.2 - 349.5 mEq/kg, and 56.1 - 446.8 mEq/kg, respectively. Thus, incorporation of acidifying ingredients is necessary when feeding dry cows without compromising feed intake when cows fed under Jordanian conditions. Several nutritional strategies have been suggested to acidify complete diet, and positively enhance Ca releasing from bones to decrease the possibility occurring milk fever in dairy cows.