Effects of starvation on cardiovascular function (including the mammary circulation) and water balance in pregnant goats.

In conscious goats, starved for 48 hr, in mid-pregnancy (70 days) cardiac output and blood volume decreased; total peripheral resistance increased; heart rate, stroke volume, blood pressure, mammary blood flow and mammary resistance were not significantly affected. In late pregnancy (132 days) cardiac output, heart rate, blood volume and mammary blood flow fell; peripheral resistance increased; stroke volume and blood pressure were not significantly affected. In mid-pregnancy, water consumption fell and the animal entered a stage of negative sensible water balance which persisted for both days of starvation. A similar change was obtained on the first day in late-pregnant goats, but on the second day water consumption increased and positive water balance was restored. Cardiac output, heart rate, blood volume and mammary blood flow was higher in fed late-pregnant than in fed mid-pregnant goats, total peripheral resistance was lower while there were no significant changes in stroke volume or blood pressure. Indications of correlations between litter size and cardiac function were obtained. The results are compared with previous studies on the effects of starvation in lactating animals and are discussed in relation to the control of cardiac function and mammary blood flow in pregnancy and lactation.