Stages of Pregnancy in Beef Heifers

Most farms will breed from every beef heifer each year in order to maintain and replenish the beef herd. The gestation period in beef heifers varies depending on the breed, size and age of the individual cow, averaging around 282 days for the Angus breed of beef cattle. This is slightly longer than the average gestation period for dairy cattle, which averages around 276 days. Additionally, male calves tend to have a very slightly longer gestation period than females. In the different stages of pregnancy, the heifer's nutritional and physical needs will change.

  1. The First Three Months

    • Miscarriage is quite likely in the first month, with up to 30 percent of heifers miscarrying in the first three weeks of pregnancy. By the sixth week of pregnancy, however, the miscarriage rate drops to 6 percent. The fetus cannot typically be identified by palpations before the 65th day of pregnancy--the fetus is the size of a mouse by the third month.

    Three to Five Months

    • At the third month of pregnancy, the fetus will be the size of a rat, growing to the size of a small cat by the fourth month. At the end of the fifth month, the fetal position is too far forward for identification through palpation, but nonetheless it is possible to feel fetal structures at this point.

    Five to Seven Months

    • At five months, the fetus is the size of a large cat, and will grow to the size of a beagle dog by the sixth month. Due to this rapid fetal growth, the pregnant heifer will require a significant amount of additional nutrients during this stage of pregnancy.

    Seven to Nine Months

    • From the size of a beagle dog at six months, the fetus will grow rapidly to a birth weight of between 50 and 100 pounds during the last trimester of pregnancy. Typically, a farmer will time the breeding season of the beef herd so that the last trimester of pregnancy occurs in the spring, when natural food such as grass is plentiful. As the fetus undergoes 70 percent of its total growth during the last trimester, the nutritional requirements of the pregnant heifer increase dramatically during this time.