Agriculture Reference
In-Depth Information
cow's estrous cycle is 21 days, and the pregnancy lasts about 280 days — or about nine
months.
Most cows have single calf births, which is a desired trait because it lessens chances for birth-
ing difficulties. Twin pregnancies occur in up to 5 percent of cattle and increases as the age of
the mother increases. A female calf with a male twin has a good chance of becoming a free-
martin due to the effect of male hormones on the female. This happens if during the preg-
nancy, the male hormones negatively influence the reproductive organ development of the fe-
male calf, causing them to be deformed. Freemartin heifers are generally sterile.
Generally, beef cows are bred to coincide to deliver their calves during the late winter or
spring. Late winter — February or March — calving has the advantage of having a heavy calf
(about 600 pounds) during the fall market period. Most people plan to market calves soon
after the summer grazing season ends, so they do not have to feed the calves the more expens-
ive grain and hay. The big disadvantage in breeding is having a calf born during poor weather
such as snow or — even worse — mud. Calves with good mothers that dry them with their
tongues and get them to stand and nurse can withstand snow and cold weather. A muddy or
wet calf quickly become can chilled and die. Spring calving on clean pastures helps eliminate
the chilling and disease problems associated with mud and snow. Timing the breeding to coin-
cide with your particular geographic area's warmer spring weather can save you time and the
heartbreak of a calf dying.
Calving
As a cow nears her delivery date, some changes will occur. About ten days before calving, her
udder may start to become firm and full. The vulva and tail head may “spring,” or become
swollen and loose, jiggling when she walks. She may isolate herself from the rest of the herd,
and she may stand with her tail raised. It is a good idea to place a cow ready to give birth into
a clean, dry pen deeply bedded with straw so the calf is born into a clean environment. If the
weather is warm and your cattle are on pasture, she also can be moved to a clean pasture.
Immediately before labor — or during stage one of labor — contractions of the uterus will
make the cow restless. She may kick at her sides, swish her tail, and get up and down fre-
quently. Cows will remain in stage one labor for as little as three hours to up to three days.
During this stage, ligaments relax, and the cervix, vagina, and vulva are dilating to allow for
the passage of the calf.
