Cow Pregnancy Stages

Photo courtesy: USDA Agricultural Research Service, Photo courtesy: Peggy Greb/USDA.

The gestation period for cattle varies, but usually lasts 276 to 283 days. Calf gender, age, breeds, and multiples are among factors affecting gestation length. Getting cows pregnant once a year is essential to the production cycle on farms.

Pregnancy in the First Three Months

Miscarriage can be as high as 30 per cent the first 21 days but will drop to just 6 per cent by day 42. At three months, the foetus is mouse-sized.

Pregnancy from three to five months

By the end of the fifth month, the foetus is too far forward in the body cavity to palpate, but structures can be felt.

Pregnancy from Five to Seven Months

Extra nutrients are needed to assure proper fetal growth, a healthy calf at birth and optimum milk production. The foetus is now cat-sized.

Pregnancy from Seven to Nine Months

Feed requirements continue to increase. The foetus makes 70 per cent of its growth in the last trimester. Farmers stop milking cows 45 to 60 days prior to the expected calving.

Pregnancy at Full-Term

As it nears full-term, the foetus ranges from about 22.7 to 45.4kg. Because the unborn calf is largely protein, the need for protein greatly increases.

Signs of Labor

Cervical dilation takes two to six hours. The cow appears uneasy. When the calf's head or feet enter the birth canal, it stimulates abdominal straining with delivery taking one-half to two hours.