Parturition

Written By: Nadine Wohlgemuth, DVM

‘Tis the Best Season of the Year …….. Calving Season!!

The journey of calving season began many months ago with careful selection of herd sires for the upcoming calving season. A lot of thought, time and money has gone into getting these cows pregnant and to the start of calving season. So, I thought this would be a good time for a quick review of the stages of parturition (calving) to help ensure we get healthy and live calves on the ground.

Stage 1:

The first stage of parturition is the dilation of the cervix. The cervix in the cow is normally closed tight right up until the start of the calving process when the cervical mucous plug is lost. Once the mucous plug is lost it will take anywhere from 2 to 24 hours for the cervix to become fully dilated. The average time is 2 to 6 hours. The hormone level of progesterone, that is required to maintain pregnancy, have declined which now allows the uterus to respond to the hormones that result in uterine contraction. The initial contractions are focused on dilating the cervix and there is minimal uterine contractions in this process. For the most part, this stage will go unnoticed by the producer but, there may be some behavioral changes such as isolation, nest building, excessive tail twitching and some mucous discharge. Checking for complete cervical dilation is important before intervening with manual extraction (pulling) of a calf.

Stage 2:

In stage two of parturition the delivery of the calf occurs. It begins with the entry of the fetal membranes and fetus into the birth canal and ends with the birth of the calf. This is the critical stage when a producer needs to be aware of how long the cow has been in active labor and at what point intervention is required. The older data suggests that the average length of time for stage two is 2 to 5 hours, however, newer data suggests that the average length for heifers is 1 hour and as little as 22 minutes for mature cows. These are the numbers I always keep track of when monitoring cows calving – if a heifer has been active labor (active labor being laying and pushing with good uterine contractions) for 1 hour and cows for 30 minutes with no progress, it is time to intervene with a vaginal exam. If the vaginal exam determines the cow requires assistance and you have not made progress extracting the calf within 30 minutes contact your veterinarian for assistance.

Stage 3:

Stage three is the passage of the fetal membranes or placenta. In cattle this normally occurs within 8 to 12 hours after delivery of the calf. If the placenta has not been passed within 12 hours of calving it is considered a retained placenta. Manual removal is not recommended as can cause damage to the uterus which will impact future fertility. Contact your local veterinarian for recommended protocol for retained placenta.

And now that the calving was successful and we have a live calf there is one more critical point to remember – colostrum! For years it has been suggested that as long as the calf nursed within the first 12 hours it would receive adequate immune transfer and protection from the colostrum. Recent data suggests that colostrum should be ingested within the first 6 hours of birth. As a producer you should monitor the calf for: time to stand and time to nurse. Data indicates that if this time is longer than 2 to 3 hours the calf’s gut has already started to close which minimizes antibody absorption. Fresh colostrum is always the best, it contains all the antibodies and white blood cells a calf requires! Second best is frozen colostrum from your own herd or powdered colostrum. White blood cells in colostrum are destroyed by the freezing and pasteurization processes therefore it is important, if possible, that a calf receive some fresh colostrum in combination with either frozen or powdered colostrum. The Headstart brand of powdered colostrum is the best colostrum product available. If you are having health issues in your calves and you are concerned your calves are not receiving adequate colostrum at birth contact your veterinarian. Your veterinarian can run blood tests on your newborn calves to assess colostrum transfer.

Happy calving!!