The impact of oxytocin on the hemodynamic features of the milk vein in dairy cows: A Color Doppler investigation

This manuscript investigates, by Color Doppler ultrasonography, the basal hemodynamic features of the left cranial epigastric vein (milk vein) of 210 Holstein-Friesian cows, throughout lactation. Blood velocity, diameter, blood flow of the milk vein (before and after milking) and milk production detected in cows administered oxytocin were compared with the same parameters found in untreated cows.Blood velocity tended to decrease throughout lactation as did milk production, whereas both diameters and blood flows tended to increase towards the end of the study. All the four parameters showed higher values in the treated cows than in the untreated ones.This study provides a detailed picture of the hemodynamic features of the milk vein of the dairy cows throughout lactation and suggest that oxytocin may exert a vasodilatory effect, in vivo, at least on the cranial epigastric vein of the dairy cow.