Research articleInvestigations of mammary and uterine blood flow in relation to milk yield, postpartum disease, and pregnancy result in dairy cows

The objective was to determine the blood flow variables in the uterine arteries and the pudendoepigastric trunks, which supply the mammary gland, and relate these variables to the occurrence of uterine disease, milk yield, and pregnancy result. To achieve this, 119 multiparous German Holstein cows were examined using color Doppler sonography once during the dry period and on Days 7, 14, 28, 42, 56, 66, 76, 86, and 96 postpartum (pp). Cows with retained fetal membranes or metritis had a higher blood flow volume and time-averaged maximum velocity and a lower pulsatility index in the uterine arteries on Days 7, 14 and 28 pp (P < 0.05). Milk yield was correlated with blood flow volume in the pudendoepigastric trunks on examination Days 7 to 96 pp with the exception of Day 76 (P < 0.05), and with time-averaged maximum velocity on Days 7 and 14 pp (P < 0.05). The pulsatility index was greater in the left pudendoepigastric trunk on examination Days 7 to 76 pp than in the right pudendoepigastric trunk (P < 0.05). Milk yield did not affect pregnancy result and was not related to uterine perfusion. Increased uterine perfusion in cows with retained fetal membrane and metritis may be due to increased uterine size attributable to delayed involution. High mammary perfusion in high-yielding cows is due to an increased demand for nutrients and oxygen. Color Doppler sonography is a useful method for the investigation of the effect of uterine disease on uterine blood flow and of the effect of milk yield on mammary perfusion.