A cow is normally pregnant for slightly longer than nine months. The average length of pregnancy is approximately 283 days, but this figure is an average. A 278-day gestation usually results in a smaller, lighter calf than a 288-day gestation. There are various factors that can affect the length of a pregnancy, such as breed, the sex of the calf, and even weather conditions.
How does a cow become pregnant?
A cow may mate with a bull to get pregnant but a semen injection is often used. Artificial insemination is more convenient as keeping bulls and feeding them isn’t necessary.
When cows are inseminated by bulls, exact calving dates may not be known but cows are expected to calve within a recognized calving season. If they have not calved at the anticipated time, they need to be checked for a normal pregnancy. Testing for pregnancy is usually done about eight to ten weeks after insemination.
How to tell a cow is ready to give birth
When a cow nears the end of gestation, her body starts changing to help with the birth process. Her udder may enlarge as early as six weeks before she calves or suddenly fill in the last few days of gestation.
Pelvic ligaments are normally very tight but will relax and appear quite loose before birth. All parts of the birth canal have to expand so the calf can come through.
Various factors can influence gestation length, such as the breed of cow, calf gender, and single versus multiple birth. Different breeds of cows have different gestation periods. The breed of cattle has the most influence on gestation length, whereas environmental factors such as temperature, nutrition, and season of the year have some influence but not that much.
A cow that gives birth a few days before her expected delivery date often gives birth to a heifer, whereas a cow that gives birth a day or two after the delivery date usually gives birth to a bull.
Some cows consistently tend to calve earlier than their projected due date. The number of calves a cow gives birth to can affect pregnancy length. Twin and triplet births are associated with a shorter pregnancy length than single births. The first three months of the pregnancy are critical and a cow may have a premature delivery for various reasons during that time.
Big male calves may consistently go a week or two past estimated due dates. Calves born in winter may also go a little longer than calves born in summer. They may also be bigger, especially if it was a cold winter. This increase in size happens not only because they are carried longer but also because the cow’s blood circulation is concentrated around the internal organs in cold weather and the fetus gets more nutrients.
Delivering at the same time
There may be a flurry of calving before a storm and calves that may have arrived within a couple of days of each other all arrive on the same day. Many cows that are ready to calve will begin labor in a low-pressure period rather than when the temperature is rising.
The birth process
A healthy calf can weigh anything from 50 to 100 lbs and it can take about two to six hours for the cow’s cervix to expand. The calf is usually quite wobbly on its legs and feeble when it is born. After the birth, the placenta is expelled and the mother cleans the calf with her tongue. In the case of cows giving birth to a first calf, labor can last from an hour and a half to two or three hours.
How long before a cow can become pregnant again after the birth?
How long a cow takes to get pregnant again can depend on a number of factors, such as the bodily condition at calving and if there were any difficulties in the calving process.
When a cow calves late, especially if she has a big calf and a hard birth, she loses that amount of time to recover and rebreed on schedule. She will calve two to three weeks later the next year.