While 70% of cows and 50% of heifers will calve by themselves, many will require assistance to avoid loss of the calf and potentially the cow themselves. It is important to understand the stages of calving, what the normal behavioural signs are for each stage, and when intervention or veterinary assistance are required. A cow gradually progresses through three stages of labour to deliver her calf.
Calf moves into position, cervix and birth canal begin to dilate.
Cervix fully dilated, calf moves through the birth canal and is eventually delivered. The calf is covered by two membranes. The outer membrane (water bag) often ruptures as it passes through the cervix, before it becomes visible. The membrane directly surrounding the calf is called the amnion and is a white-clear membrane when compared to the darker outer membrane.
In normal deliveries, this stage lasts from 30 minutes to four hours, but may be longer in heifers. If a cow is moved during labour, the point at which she is moved can increase the length of labour.
A longer stage 2 labour is associated with increased stillbirths, dystocia and inflammation post-calving.
Passing of the placenta, which normally occurs within 30 minutes to eight hours post-calving.
It is important for each farm to establish their own standard operating procedure when assisting during calving, along with proper staff training. Guidelines for making the decision to intervene include:
A uterine examination will tell you a few things – if the cervix has dilated properly, if the calf is dead or alive, or if the calf is presenting normally.
A normal forward presentation (typical) is when the front legs and head come first and the calf is lying on its stomach (ie calf’s back next to cow’s back).
A normal backwards presentation is when the back legs are coming first, again with the calf lying on its stomach.
Never pull a calf presented in any other position, because you could kill both the cow and calf.
A calf that is coming backwards needs to be delivered more quickly as they can suffocate, but this may be more difficult, as the calf’s head will not have dilated the uterus.
If the calf is not presenting normally
Look for landmarks that will help you identify how the calf is presented e.g., a knee or hock joint, a tail, some part of the head (if the head is facing back it might be an ear). Many of these positions can be corrected if found early in the labour process.
If there is a leg down, cup the hoof in your hand when repositioning to prevent uterine damage. If you are inexperienced call for veterinary practitioner as this can be difficult. It may happen that you can’t feel any part of the calf, and if the labour has been progressing for some time this can mean that the uterus hasn’t dilated or there is a uterine torsion and veterinary assistance will be required.
Is the calf too big?
Determining the size of the calf relative to the birth canal is critical and requires some experience.
Proper facilities and hygiene are essential for a safe and successful calving. Good ropes, a calving jack, gel and clean water are other essentials, and record keeping will aid in calving management.