Calcium chloride is a better calcium source rather than calcium carbonate for weanling pigs.

Two experiments were conducted to evaluate the effects of calcium (Ca) levels in weanling pigs (Landrace × Yorkshire × Duroc). In experiment 1, one hundred and eighty weanling pigs were randomly allotted to one of the three treatments. The treatments were low (Ca 0.60% in phase 1 and 0.50% in phase 2), standard (Ca 0.72% in phase 1 and 0.66% in phase 2), and high (Ca 0.84% in phase 1 and 0.72% in phase 2). In experiment 2, hundred and forty weanling pigs were randomly assigned to one of four treatments differing in Ca levels (high and low) and sources (CaCl 2 and CaCO 3 ) in a 2 × 2 factorial arrangement. There were 10 pigs per replicate in both experiments, with 6 replicates in each treatment, and they were conducted in two phases (phase 1, days 0-14; phase 2, days 15-28). In experiment 1, body weight (BW), average daily gain (ADG), and growth to feed ratio (G/F) increased as the Ca level decreased ( p < 0.05). P digestibility was higher in the low-Ca diet group than in the high-Ca diet group ( p <0.05). In experiment 2, the final BW, ADG, and G/F increased in the CaCl 2 diet group compared with the case in the CaCO 3 diet group ( p < 0.05). The digestibility of crude protein (CP), Ca, and P was higher in the CaCl 2 diet group than in the CaCO 3 diet group ( p < 0.05). Cl - levels were higher in the CaCl 2 diet group than in the CaCO 3 diet group ( p < 0.05). The bicarbonate (HCO 3 - ), base excess (BE), and electrolyte balance (EB) levels were lower in the CaCl 2 diet group than in the CaCO 3 diet group ( p < 0.05). Hematocrit increased as the Ca level decreased ( p < 0.05). The HCO 3 - interacted with the Ca sources and thus, affected the Ca levels ( p < 0.05). Bone ash, Ca, and P were downregulated in the low-Ca diet group compared with the case in the high-Ca diet group. Overall, the low dietary Ca supplementation led to greater growth performance. Furthermore, CaCl 2 appeared to be a better Ca source than CaCO 3 because of the greater digestibility of CP, Ca, and P, and improved EB.