Pelvic area measurements of heifers as a predictor of calving difficulty

In order to improve the economic situation of beef cattle enterprises in the Southeast and the nation as a whole, it is necessary to look at the areas of production which present problems related to the actual number of calves, pounds of calf, or pounds of meat marketed.

In doing this, one should look at the overall picture of beef cattle production to see where the greatest improvement is needed. It is an understatement to say that no areas exist where progress could not be made. Improvement in genetics and breeding is being made with the tools of production testing and type improvement programs. Studies in nutrition, breeding, and engineering have improved feed efficiency, carcass quality, and feedlot practices. However, if one compares the number of animals marketed with the number of breeding animals on farms, obviously, an increase in what is commonly called "calf crop" would be of significant aid in increasing the amount of product marketed and therefore the amount of profit to be made.

An increase in calf crop can best be made by determining at what point or points calf mortality is greatest and correcting those specific problems. Three reasons are generally given for low calf crops. These reasons are failure of cows to become pregnant, death of fetuses, and death of calves at or shortly after birth. Of these three the failure of cows to become pregnant and the loss of calves at or near birth have been earlier considered as being most important. However, today most authorities seem to agree that the three factors are about equal in importance.

Research reported herein was designed to study methods of predicting and controlling calf losses at birth through measurements of the pelvic area of heifers. Specific objectives were to determine or evaluate the following:

1. Repeatability and accuracy of the measurements.

2. Correlations between the measurements of a young heifer and those of the same heifer immediately prior to parturition.

3. Relationship of internal pelvic area to certain external pelvic measurements.

4. Effect upon birth difficulty of maternal pelvic area and fetal weight and size.