The effect of thyroxine on the metabolism of lactating cows. 2. Calcium and phosphorus metabolism

Publisher Website
Google Scholar
Abstract
Eight Ayrshire cows in mid-lactation were used to determine the effect of thyroxine admn. on the metabolism of Ca and P. With 1 exception, the Ca balances were negative both for the treated and for the control animals throughout all the expts. With 2 of the cows which were fed more liberally than the others, the output of Ca was greatest in the thryoxine period, and this was attributable to an increase in the fecal metabolic Ca resulting from the hormone treatment. There was no increased output of Ca in the urine. The apparent digestibility of the dietary Ca was found to be very low. This, together with the negative balances, might well result in thyroxine treatment leading to a depletion of Ca reserves which would be dangerously excessive unless dietary measures were taken to make good the loss. Unlike those of Ca, the P balances (obtained for 2 cows only) were positive throughout the whole expt., thyroxine actually tending to increase the amt. of P retained. The Ca content of the milk was not affected by thyroxine, but the P content was significantly increased.

This publication has 2 references indexed in Scilit: