Effects of oral calcium bolus supplementation on intracellular polymorphonuclear leukocyte calcium levels and functionality in primiparous and multiparous dairy cows

摘要

The objectives of this study were (1) to characterizeCa levels and polymorphonuclear leukocyte (PMN)function in primiparous and multiparous animalsfollowing oral Ca bolus supplementation, and (2) todetermine differential responses of boluses containinga lower dose of Ca than traditionally used in primiparousanimals on Ca levels and PMN function. Jersey× Holstein crossbred animals (n = 104) were enrolledwithin 24 h of parturition. All animals were blockedby time relative to calving and randomly assigned totreatment. The Ca boluses were composed of a mixtureof Ca chloride, Ca sulfate, and Ca propionate. For objective1, animals were assigned to control (CON; noCa supplementation), or a series of 2 Ca boluses given24 h apart for a total of 50 g of Ca. Objective 2 treatmentsincluded control (CON; no Ca supplementation),a series of 2 Ca boluses given 24 h apart containing 50g of Ca, or a series of 2 Ca boluses given 24 h apartcontaining 25 g of Ca. Blood samples were collectedon d 1 (＜24 h), 2, 3, 5, and 7 relative to parturition.Total serum Ca, serum haptoglobin, PMN intracellularCa, PMN intracellular Ca after stimulation with anenvironmental Escherichia coli, PMN L-selectin surfaceexpression, and PMN phagocytic and oxidative burstactivities were analyzed. For objective 1 a tendencywas detected for a treatment difference on basal intracellularPMN Ca and a treatment difference on E.Coli-stimulated intracellular PMN Ca. We detected aparity × DIM effect for PMN oxidative burst intensity.However, no other interactions or parity effectson other functional PMN variables were detectable. Inprimiparous animals, we found a treatment differencefor E. coli-stimulated intracellular PMN Ca among animalsgiven 50 g of Ca but no treatment difference onbasal intracellular PMN Ca. The 50 g of Ca treatmentincreased both PMN phagocytosis and oxidative burstintensities. Supplementing animals with 50 g of oral Caincreased intracellular PMN Ca and influenced PMNfunction.