Fall calving season is upon the Oklahoma ranches that have fall and winter 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.  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.  Newer 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 in mature cows. 

    Table 1.  Research Results of Length of Stage II of Parturition 

                                                                No. of                     Length of 
                                                                Animals                   Stage II 
     USDA (Montana)                            24 mature cows           22.5 min. 
     USDA (Montana)                            32 first calf heifers        54.1 min. 
     Oklahoma State Univ.                      32 first calf heifers        63.4 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.  If you cannot safely deliver the calf yourself at this time, call your local 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.  Using the concept of evening feeding to get more heifers calving in daylight, and giving assistance early will save a few more calves, and result in healthier more productive two-year cows to rebreed next year.   For more information on topics concerning assisting cows and heifers at calving time, stop by your Local OSU County Extension Office and ask for a circular E-906 "Calving Management".