Effectiveness of calcium chloride in increasing blood calcium concentrations of periparturient dairy cows

Calcium chloride supplements such as gels and drench were studied to determ ine their effectiveness for increasing blood serum Ca concentrations in per iparturient dairy cows. Multiparous, pregnant Holstein dairy cows (n = 36) were assigned to one of four treatments. After calving, cows in four treatm ents received basal diet and two doses of either control inert gel (CON), g el containing CaCl2 and vitamins (CVG), gel containing CaCl2 and minerals ( CMG), or CaCl2 as drench containing vitamins (CVD). The first dose was give n within 2 h after calving and the second dose 12 h after the first dose. E ach dose provided .07, 54.5, 56.0, and 33.2 g of elemental Ca in CON, CVG, CMG, and CVD treatments, respectively. Blood samples were collected at 0, 1 5, 30, 60, 180, and 360 min after each oral dose. The blood serum Ca concen trations were 6.26, 7.56, 6.20, and 5.96 mg/dL during the pretreatment peri od and deviated -13.5, 7.1, 9.3, and 18.1% from pretreatment levels at 18 h after the first dose in CON, CVG, CMG, and CVD treatments, respectively. T he average changes in serum P from pretreatment levels were not different a mong treatments. Serum Mg concentrations remained below the pretreatment le vels in all four treatments. Blood serum beta-hydroxybutyrate during the fi rst 2 wk and milk yields during the first 4 wk of lactation were the same i n all treatments. Three cases of clinical milk fever were observed in CON t reatment and one case in CVD treatment. The oral supplements of CaCl2 as ge l or drench increased the blood Ca levels in periparturient dairy cows. Inc reased supply of Ca through oral supplements of CaCl2 may prevent milk feve r in cows that are marginally hypocalcemic.