Before
the fall calving season commences, now is the time to put together and
post a protocol for family members and hired employees to follow when
they find a cow or heifer starting in the process of calving. An issue
facing the rancher at calving time, is the amount of time heifers or
cows are allowed to be in labor before assistance is given. Formerly,
traditional text books, fact sheets and magazine articles stated that
“Stage II” of labor lasted from 2 to 4 hours. “Stage II” is defined as
that portion of the birthing process from the first appearance of the
water bag until the baby calf is delivered. Research data from Oklahoma
State University and the USDA experiment station at Miles City, Montana
clearly show that Stage II is much shorter, lasting approximately 60
minutes in first calf heifers, and 30 minutes or less in mature cows.
Table 1. Research Results of Length of Stage II of Parturition
Source
|
No. of Animals
|
Length of Stage II
|
USDA (Doornbos, et al.1984. JAS:59:1)
|
24 mature cows
|
22.5 min.
|
USDA (Doornbos, et al.1984. JAS:59:1)
|
32 first calf heifers
|
54.1 min.
|
Oklahoma State Univ.
(Putnam, et al. 1985. Therio:24:385)
|
32 first calf heifers
|
55.0 min.
|
In these studies, heifers that were in stage
II of labor much more than one hour or cows that were in stage II much
more than 30 minutes definitely needed assistance. Research information
also shows that calves from prolonged deliveries are weaker and more
disease prone, even if born alive. In addition, cows or heifers with
prolonged deliveries return to heat later and are less likely to be bred
for the next calf crop. Consequently a good rule of thumb: “If the
heifer is not making significant progress 1 hour after the water bag or
feet appear, examine the heifer to see if you can provide assistance.
Mature cows should be watched for only 30 minutes before a rectal
examine is conducted.” Make certain the cervix is completely dilated
before pulling on the chains. If you cannot safely deliver the calf
yourself at this time, call your local large animal veterinarian
immediately.
Most ranches develop heifers fully, and use calving ease bulls to
prevent calving difficulties. However, a few difficult births are going
to occur each calving season. Giving assistance in a timely manner will
save a few more calves, and result in healthier more productive two-year
old cows to rebreed next year.
