EFFECT OF DIFFERENT LEVELS OF PRE AND POSTPARTUM DIETARY CATION-ANION DIFFERENCE ON MILK PRODUCTION AND PLASMA MINERAL CONCENTRATIONS OF HOLSTEIN COWS

In order to survey the effect different levels of pre and postpartum dietary cation-anion difference (DCAD) on milk production, milk composition, plasma mineral concentration and health status twenty four Holstein cows were used in a split-plot in time design with a 2×2 factorial arrangement as a completely randomized design. Before calving, cows were divided into two groups of 12 each, one group was fed by a diet of -100 DCAD (meq/kg DM) and another group by +100 DCAD (meq/kg of DM). After parturition animals in each group were divided into two group of 6 each and one group fed a diet of +200 DCAD (meq/kgDM) and the other fed a diet of +400 DCAD (meq/kgDM). Feed intake was recorded weekly and blood samples were collected on days -12, -2, +2and +12 of parturition. Prepartum feeding of the diet with -100 meq/kg DM DCAD increased plasma concentration of Ca, Mg, Cl and S. After parturition, feeding the diet with +400 DCAD increased significantly (P<0.01) DMI, fat corrected milk production, milk fat and total solid concentrations and plasma Na and K concentrations . Prepartum DCAD did not affect plasma mineral concentration, DMI, and milk production of lactating cows. No case of milk fever was observed in dairy cows. However, different levels of DCAD did not significantly affect retained placenta and hypocalcemia incidences, their risks were reduced for animals fed anionic diets. So it was concluded that low level of DCAD on late gestation can be useful to improve animal health and high of DCAD after parturition had positive effect on animal performance.