The Effect of Experimental 17-beta Estradiol Administering on Calcium Metabolism Regulation in Young Laying Hens

Three groups of 128-day-age laying hens were i.m. injected with 17-beta estradiol for eight days, in different doses, vs. an untrated control group. Calcium from ingesta, eggshell, feces and mineral bone content was determined. At the end of the experimental treatment, the results showed an increase in the egg yield in all treated hens vs. control. between 6% and 8%, depending on the estradiol dose, but not proprotionally to the dose of estrogen administered. The amount of daily absorbed calcium ranged between 1.37 and 1.77 for the three experimental groups vs. 0.97 in control. Calcium concentration of the eggshell and total calcium content if the egg was not significantly influenced. The daily mean amount of calcium excreted by egg was increased vs. control. Blood calcium values ranged between 5.65 and 7.16 meq/100 mL vs. 4.45 meq/100 mL of plasma in control (P=0.0081). The amount of mineral content of the bone increased while calcium excreted in feces and urine was less than in control. Blood levels of calcitonin, parathormone, progesterone and calcitriol were modiffied, relatively proportional the the estrogen dose.