Study results demonstrated that cows with assisted births (dystocia) had a longer period from the amniotic sac appearance or feet appearance to birth and increased incidence of stillbirths compared with cows with unassisted calving. Although not significant, the researchers say it is important to note that the time spent in labor varied for first-lactation animals and cows with multiple lactations.
This study suggested that calving personnel should start assisting cows 70 minutes after amniotic sac appearance (or 65 minutes after feet appearance) outside the vulva (based on births without assistance). Under field conditions, the observation of amniotic sac or feet appearance as calving progresses are clear and concrete landmarks that calving personnel can easily identify. Early intervention has the potential to prevent stillbirths, but also has the potential for dam injury due to lack of proper dilation of soft tissues.
When a calf malpresentation is evident (like the appearance of one foot outside the vulva) immediately after amniotic sac appearance, or for uterine torsions (where the amniotic sac or feet do not appear outside the vulva), obstetric intervention is rendered. The time spent in labor (straining) combined with the time from the amniotic sac or feet appearance to birth and the assessment of calving progress (as described for non-assisted births) should be used as guidelines to determine the appropriate time for intervention during difficult births under field conditions. Keep in mind, these reference times should be interpreted in combination with adequate obstetrical knowledge and examination.
To learn more about when and how to assist with calving, plan to attend the Carver County/University of Minnesota Dairy Expo on Monday, February 18, 2013 in Norwood Young America. At that conference, Dr. John Zimmerman will be discussing and demonstrating how to deal with calving conundrums. To view a complete program brochure online, go to http://z.umn.edu/dairyexpo.
Source: Laura Kieser, Extension Educator, University of Minnesota Extension, Scott and Carver Counties