Abstract: This trial was conducted to determine the effect of diets containing treated alfalfa silage with hydrochloric acid (HCl) (12 g kgG1 DM) or anionic salts (7.51% Sulfate, 29.8% Chloride, 11.49% Calcium and 2.98% Magnesium) on pH and mineral concentration (Ca, P, Cl, Mg, Na and K) of blood and urine of Holstein close-up dairy cows. In addition, milk yield and retained placenta after parturition (6 weeks) were recorded. Treatments were; Basal Diet (BD; corn silage (17 kg), alfalfa hay (2.4 kg), wheat straw (0.7 kg) and concentrate (5.5 kg)), HCl treated alfalfa silage (12 g kgG1 DM) substituted of alfalfa hay in basal diet (BDH) and basal diet + anionic salts mixture (BDA, 300 g/head/d). Experimental diets were fed to 12 Holstein dry cows (n = 4) during 18-33 days before calving. Animals were fed individually in tie stall as ad libitum. Feed intake was recorded daily and samples of blood (via jugular vein) and urine were taken at the pre and two weeks after the feeding. Samples were analyzed for pH and minerals concentrations. Results indicated that the effect of diets on urinary pH (7.06, 6.6 and 6.79 for treatments BD, BDH and BDA, respectively), blood pH and blood and urine minerals concentrations was not significant (p>0.05). Cows fed acidified diets had lower placenta excretion time (h) and more milk production than those of basal diet. It is concluded that blood and urine acid-base properties did not affected by the experimental diets when included by HCl or anionic salts.

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