Typically, calving time is when the highest incidence of cow and calf health challenges need to be met.
Knowing what is normal and what is not is the first step in identifying when there is a problem and whether intervention is necessary.
At a Dairy HIGH online discussion group in July, Dr Craig Dwyer from Smithton Veterinary Service shared some very useful information on common calving time problems.
The three stages of labour
Stage one is when the cow is getting ready to calve.
During this stage, which will take from three to six hours in cows and up to 12 hours in heifers, you are likely to see:
- Separation from the herd
- Tail lifting and swishing
- Mild kicking of the belly
- Increased lying down-getting up
- Presence of 'water-bag'
If stage one lasts for more than six hours, the cow should be examined to determine if there is a problem.
In stage two, the cervix is fully dilated and the cow will have visible abdominal contractions ('straining'), the water bag breaks, the calf enters the birth canal and is born.
Stage two normally takes 30 minutes to four hours.
In this stage, the cow needs to be making progress the whole time - for example, if the tip of the feet and nose have been visible for 30 minutes and there hasn't been any progress during that time, it indicates there could be a problem and the cow should be examined.
Stage three occurs two to 12 hours after the calf is born with the expulsion of the foetal membranes.
In a normal calving with the delivery of a healthy calf, the calf will stand and start suckling during this stage. This results in a release of oxytocin (a hormone) within the cow which acts on the uterus and helps foetal membranes detach and be expelled.
The receptors in the uterus are only 'open' to oxytocin for six to eight hours after birth.
If the cow does not have a natural release of oxytocin during this time, for example if the calf is born dead, she is more likely to have retained foetal membranes.
To avoid this, the cow could be milked which will stimulate the release of oxytocin, or she could be given an injection of oxytocin. It is very important to make sure she has actually calved (and there isn't a twin still to be born) before giving oxytocin - oxytocin causes the uterus to contract which makes it difficult to deliver a calf.
Difficult calvings
There are several reasons why a cow may have trouble delivering a calf:
- Excessive body condition (greater than BCS 5.5)
- Calf is too big/dam is too small
- Weak or absent uterine contractions
- Twisted uterus
- Abnormal delivery position of the calf
Some of the causes of difficult calving can be managed by having well grown heifers, appropriate sire selection and a good transition cow diet - all these will reduce the number of cows requiring calving assistance.
However, there will be some cows needing help and the first step is to be prepared.
This involves having:
- A well-stocked calving box - ropes, gloves, calving lube, oxytocin, anti-inflammatory drugs and a calving jack
- Adequate restraint - a crush or tied with a halter to a fixed object
- Two buckets of warm water - liquid soap and disinfectant
- Good hygiene - all equipment (including your arms) must be thoroughly cleaned to avoid contamination of the reproductive tract
Assistance should be given to a cow if there is no progression from stage one labour after six hours or no progression from stage two labour after two hours.
If uncertain, it is better to intervene early rather than leave it too long.
The normal presentation for a calf being born is two front feet and headfirst, however, it is not that abnormal for a calf to be born backwards - an overseas study showed 40 per cent of calves were born backwards.
Malpresentations include 'head back', 'head to the side' and 'rump first'.
It is very important to feel and work out what you are dealing with before starting to pull the calf out.
You need to be sure you have the two front legs, or the two back legs - not a combination of both, or a leg from a second calf.
If you are not able to determine the position of the calf or are uncertain about what to do, ask for help - either from someone with more experience or a vet.
If you can determine the problem with the delivery of the calf and decide to assist the cow yourself, assess the size of the calf relative to the birth canal.
The calf should be able to be delivered if you can fit your hand over the calf's head in the pelvis of the dam (calf coming forwards) or your hand can fit over the calf's hips in the pelvis of the dam (calf coming backwards).
Attach the calving ropes (or chains) to the calf's legs using a double half hitch.
Use calving lube as this will make the delivery of the calf easier.
Whether you are trying a manual pull or using a calving jack or pulley, if the calf has a normal presentation, it is important to apply traction to each leg alternatively and pull in a slightly downward motion.
When both front legs are out of the vulva, traction can be applied on both legs at the same time.
Coincide traction when the dam is straining and once the shoulders have passed through the vulva, rotate the calf 90 degrees to help prevent 'hip lock'.
You should call the vet if:
- The cow has a prolonged calving and you can't assist the cow yourself
- There is a prolonged stage 1 but you can't find either the legs or the head.
- You cannot advance your arm into the birth canal.
- There is no progression in the labour after 20 minutes of you trying to deliver the calf.
- There is a fetid smell or an obviously dead calf.
- The calf is very large - it feels like there is no room.
If you deliver a live calf, it should:
- Take its first breath in 30 seconds.
- Lift its head in one to two minutes.
- Roll onto its chest in two minutes.
- Attempt to stand in 15 minutes.
- Begin shivering in 30 minutes.
- Be standing in one hour.
- Be suckling in two hours.
The calf should also have:
- A rectal temperature of 38.8-39.4 degrees after birth and stabilising to 38.3-38.8 degrees within one hour.
- A heart rate of 100-150 beats per minute, regular rhythm, strong pulse.
- 50-75 breaths per minute.
- No swelling or discolouration of the head, limbs or tongue.
- Pink, moist mucous membranes.
The calf should also respond to stimulation with head shaking and movement of the limbs.
If the calf isn't behaving normally, it needs assistance.
Position the calf on its chest with the hind legs pulled forward on either side of the body.
Clear mucous from it's nostrils and mouth.
Stimulate breathing by rubbing the calf's body, pinching or tickling the nostrils or splashing water into its ear.
If the calf is cold, find some way of warming it up - a warm bath, blankets, hay, hair dryer, heater, etc.
Calf resuscitation kits are available which deliver oxygen to the lower airways of the calf.
This could be included in your calving box.
- Craig also shared tips on how to deal with milk fever, prolapse and retained foetal membranes. A recording of the discussion group is available in the TIA Dairy Discussions Facebook group, on YouTube, or if you would like the link emailed to you, please contact me at Lesley.Irvine@utas.edu.au.
