Pelvic Measurements For Reducing Calving Difficulty

University of Nebraska - Lincoln
DigitalCommons@University of Nebraska - Lincoln
Historical Materials from University of Nebraska-
Lincoln Extension
Extension
1-1-1987
G87-895 Pelvic Measurements for Reducing
Calving Difficulty
Gene H. Deutscher
University of Nebraska - Lincoln
Deutscher, Gene H., "G87-895 Pelvic Measurements for Reducing Calving Difficulty " (1987). HistoricalMaterials from University of
Nebraska-Lincoln Extension. Paper 325.
http://digitalcommons.unl.edu/extensionhist/325
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G87-895-A
(Replaces G75-206)

Pelvic Measurements for Reducing Calving
Difficulty
Pelvic measurements in heifers and bulls can be an important tool to help reduce the incidence
and severity of calving difficulty.
Gene H. Deutscher, Extension Beef Specialist
Importance of Pelvic MeasurementsPelvic Area and Calf Birth Weight Relationship
Using Heifer Pelvic Measurements
Heritability of Pelvic Area
Using Bull Pelvic Measurements
How to Measure Pelvic Area
Conclusion
Calving difficulty results in a major economic loss to beef producers. This loss is estimated at $750
million annually nationwide.
Calving difficulty increases calf death loss, cow mortality, laborand veterinary costs; it delays the return
of cows to estrus and reduces conception rates. It also lowers calf weaning weight and market value,
which results from breeding young heifers and cows to easy calving bulls to reduce calving difficulty.
Studies show calf losses of 4 percent within 24 hours of birth for calves born unassisted, compared to 16
percent for calves requiringassistance. Montana research indicates 57 percent of all calf losses were due
to dystocia (calving difficulty).
Calving difficulty is becoming a greater concern for beef producers because of the increased emphasis
on rapid growth rates, heavier weaning weights and improved cow efficiency. As producers select bulls
for more growth, larger calves at birth and more calving difficulty can beexpected.
Importance of Pelvic Measurements
Many factors are associated with calving difficulty, including: small first-calf heifer; large fetus; male




fetus; small pelvic size of dam; long gestation; heavy birth weight sire; dam too thin or too fat and
abnormal fetal presentation at calving. Research indicates the major cause of dystocia is a disproportion
between the calf size at birth(birth weight) and the cow's birth canal (pelvic area).

Figure 1. Vertical and horizontal measurements are obtained
to determine pelvic area.
Figure 2 shows the relationship of calf birth weight and cow
pelvic area to the incidence of dystocia in 2-year-old heifers in a
study in Montana. An Oklahoma study showed calves born
unassisted were 7 pounds lighter at birth compared tothose born
with assistance. Heifers with small pelvic areas experienced an 85
percent difficulty rate compared to 31 percent difficulty for
heifers with large pelvic areas. South Dakota research showed
heifers with below average pelvic areas (less than 140 cm²) had twice the incidence of dystocia as those
with above average pelvic areas (49 percent versus 24 percent).

Figure 2.Relationship of heifer pelvic
area, calf birth weight and incidence of
dystocia in 600 two-year-old heifers.
(R.A. Bellows 1983).
Large framed cows tend to have large
pelvic areas and proportionately heavier
calves at birth, offsetting any size
advantage. Selecting a cow on size alone
seems ineffective.
A low relationship has been found
between a heifer's pelvic area and the...