Availability of calcium from skim milk, calcium sulfate and calcium carbonate for bone mineralization in pigs

Dairy products provide abundant, accessible calcium for humans, while some calcium sulfate-rich mineral waters could provide appreciable amounts of calcium. But there is little evidence that this calcium is as available as milk calcium for making bone. The availability of calcium was studied by monitoring bone parameters in 2-month-old pigs fed restricted amounts of calcium (70% RDA) for 2.5 months. The 3 main (<formula notation="TeX">$\geq 50\%$</formula> Ca intake) Ca sources were either CaCO<formula notation="TeX">$_3$</formula> or CaSO<formula notation="TeX">$_4$</formula> or skim milk powder (29% of the diet). The bones of the pigs fed the "milk" diet had higher (<formula notation="TeX">$P<0.01$</formula> ) ash contents, breaking strength and density (DEXA) than those of the two others groups, in which the bone values were similar. Thus, the calcium provided by a diet containing milk appears to ensure better bone mineralization than do calcium salts included in a non-milk diet. The calcium restriction may have enhanced some milk properties to stimulate calcium absorption in these young, rapidly growing pigs.