With many producers about to embark on another calving/lambing season, it is good to review the stages of calving/lambing. Gestation length varies between 279-289 days in cattle and 144-155 days in sheep. There are three stages:
- Cervical Dilation (softening of ligaments, udder development, nesting behavior, mucous plug expelled, but no abdominal pushing) -about six hours long
- Fetal expulsion (water bag appears, abdominal pushing)-about 2 hours long
- Give 1.5 hours of "pushing" for part of calf or lamb to appear
- Give another 30-45 minutes after part of the calf or lamb is showing for it to be born
- Placental expulsion (usually "clean" within 2-6 hours, longer than 12 hours is considered a retained placenta)
If any one of the stages takes longer than anticipated, it may be a sign that the animal is in distress and needs assistance.
Although the above times are a guideline to a normal calving or lambing, sometimes difficulties arise. A dystocia is a difficult or problematic birth. A producer can expect about 10-15% dystocias in heifers and 3-5% in cows. Rates of dystocias can be influenced by choosing easy calving bulls, culling cows with a previous history of problems, proper nutrition, breeding cows at an appropriate weight and age. Breed, age, nutrition, body condition score, pelvic area, genetics, sex of calf/lamb, size of dam and calf can all play a role in whether things go smoothly or not. If a calf/lamb is in a forward presentation, that is much easier than a backwards or breech (bum first) presentation. An upside down position or an abnormal posture (example leg or head back) are also examples when someone needs to intervene.
Variations from the norm:
- Ring womb-This is when the cow's/ewe's cervix only partially opens despite having adequate time to dilate. Ring womb prevents the calf/lamb from being able to pass through the birth canal. Often a c-section is required.
- Uterine torsion-This is when the uterus flips over thus blocking the birth canal. When the producer puts his arm in to check the cow, the arm tends to twist or rotate in a corkscrew fashion, indicating a problem. Occasionally the veterinarian will try to detorse the uterus with a detorsion bar or do a c-section.
- Backwards- A cow can calve a backwards calf on her own; however, her birth canal needs to be larger to accommodate a backwards birth. Sometimes these end up needing a c-section.
- Breech-This is when the calf is trying to be born "bum first" ( no legs are visible). Breach births require intervention. The veterinarian will try to bring the back legs up and into the birth canal if there is room. Occassionally the breach calf is too big to be repositioned, or having been repositioned, it is discovered the birth canal is too small to accomodate that calf. In those cases, a c-section may be the next option.
- Uterine prolapse-Otherwise known as "throwing her calf bed". This is a veterinary emergency. This is when a cow continues to push after the calf is born, and she pushes her uterus completely out. The cow must be restrained and the veterinarian called immediately, as this can lead to the cow bleeding to death. If the cow survives this, she can go on to have many more calves and rarely repeats the uterine prolapse. A difficult pull, a lack of calcium or magnesium or protein, or giving birth on a slope can predispose the cow to a uterine prolapse. Getting the cow up as soon as possible following calving will help prevent this. Your veterinarian may be able to recommend medications and mineral protocols to help prevent this as well.
- Hypoxic calves-These are babies that lack oxygen because of a stressful or too slow birth. Often they have a yellow discoloration. This is due to the meconium or first feces being passed by the calf, while in the uterus. Yellow discoloration indicates an emergency and the calf needs to be born soon or it will not survive. Once a hypoxic calf is born, a bit more attention to making sure it gets colostrum (mother's first milk) and learns how to feed properly will help increase survival rates.
The best way to get through calving/lambing season is to hope for the best, but prepare for the worst. Muddy lots, crowding, and chilling can increase numbers of sick, and severity of disease significantly. A safe place to put a cow needing assistance (ie. a calving pen with a head gate and sides that swing around) will keep the handler safe as well as prevent the cow from injuring themselves or the unborn calf. (Calving pens should be cleaned and disinfected between calvings.) Having a plan for transportation, in case an emergency trip to the veterinary clinic arises can cut back on the stress of having to line up a trailer or get roads plowed in the face of an emergency.
Below is a checklist of things to have on hand for calving/lambing:
- chains and handles
- veterinary phone number
- calf box with heat lamp
- tags and tagger
- Vitamin E Selenium
- calf puller
- sleeves and gloves
- bottle with nipple
- bag feeder
- dehorn paste
- other supplies as suggested by your veterinarian