Carryover effects of potassium supplementation on calcium homeostasis in dairy cows at parturition.

摘要: The purpose of this study was to test whether supplementation with K improves bone mineral density (BMD) in older cows so that by parturition their is better able mobilize Ca. Twenty-four Holstein Friesian (6 mo pregnant, lactating, and third or later lactation) were allocated 2 equal groups individually fed twice daily a total diet comprising low oaten hay plus pelleted concentrate fortified without K2CO3 achieve 3.12% K/kg DM the K-supplemented (KS) compared 1.50% for control cows. respective diets from beginning sixth month pregnancy until wk before expected date parturition. strategy use stimulate mild increase extracellular pH potentially improve BMD well parturition, when high contents are considered safe, but cease supplementing few weeks prepartum, intakes known be problematic. expectation effect denser would carry through benefit cow's plasma Ca, P, Mg status at Prior period supplementation, part commercial pasture-based herd, which they returned end treated as 1 group least 11 d prepartum 42 next lactation. Supplementation successfully induced sustained urinary throughout late lactation into dry period, expected. KS consistently averaged urine 0.25 ± 0.10 U higher than controls. However, there no significant on BMD, concentrations, osteocalcin, deoxypyridinoline:creatinine P concentrations during immediately after cessation nor where any carryover effects Instead, an unexpected decrease concentration extended 0.5 2.5 postpartum. timing decline paralleled declines 1,25 dihydroxy-vitamin D3 excretion Ca Mg, whereas increased; all changes consistent hypomagnesemia could risk hypocalcemia. These data suggest that, addition well-documented negative dietary can over trigger Because did not it possible conclude against ability reduce hypocalcemia