Article

The predictive value of pelvimetry on beef cattle

Veterinary Infectious Disease Organization, Saskatoon, Saskatchewan.
Canadian journal of veterinary research = Revue canadienne de recherche vétérinaire (Impact Factor: 1.02). 08/1993; 57(3):170-5.
Source: PubMed

ABSTRACT

To elucidate reasons for failure of pelvimetry to predict dystocia, we collected data from 1146 heifers and 210 cows in five beef cow herds in Saskatchewan. We assessed the reliability of pelvic area measurements, the generalizability of findings, various modifications of the technique, and the statistical association between pelvic area measurements and dystocia. The repeatability (kappa) of pelvic area measurements between and within veterinarians for the Rice and Krautmann pelvimeters were low to moderate, indicating pelvic area measurements were imprecise. The positive predictive values and sensitivities of pelvic area measurements were consistently poor across herds, years of study, breeds of heifers, times of measurement, various pelvic area cut-off points, and sires. Various modifications of the technique, including pelvic area/calf birth weight ratios, pelvic area/heifer weight ratios, and Ko's calving prediction equation were also poor on-farm tests for predicting dystocia. Although the mean pelvic area in heifers with dystocia was smaller than those without dystocia, there was a large overlap in the distribution of their measurements. Far too many heifers with a small pelvic area had no dystocia (false positives) and far too many heifers with a large pelvic area had dystocia (false negatives) for pelvimetry to be useful. We conclude there is little evidence to justify the continued use of pelvimetry as an on-farm test to reduce dystocia in beef cattle.

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    • "Third, increased plasma estradiol and relaxin concentrations at parturition[35,36]and abdominal straining during fetal expulsion may transiently increase intrapelvic dimensions373839, particularly the intrapelvic height[40]. A fourth area of concern in using maternal intrapelvic dimensions to predict dystocia is whether the measures have adequate intraobserver and interobserver repeatability[28,38,40414243. Despite these concerns, measurement of intrapelvic dimensions is believed to be of value in predicting dystocia in dairy cattle[8,26]. "
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    ABSTRACT: The objective of this study was to determine the clinical utility of measuring calf front hoof circumference, maternal intrapelvic area, and selected morphometric values in predicting dystocia in dairy cattle. An observational study using a convenience sample of 103 late-gestation Holstein-Friesian heifers and cows was performed. Intrapelvic height and width of the dam were measured using a pelvimeter, and the intrapelvic area was calculated. Calf front hoof circumference and birth weight were also measured. Data were analyzed using Spearman's correlation coefficient (rs), Mann-Whitney U test, and binary or ordered logistic regression; P < 0.05 was significant. The calving difficulty score (1-5) was greater in heifers (median, 3.0) than in cows (median, 1.0). Median intrapelvic area immediately before parturition was smaller in heifers (268 cm(2)) than in cows (332 cm(2)), whereas front hoof circumference and birth weight of the calf were similar in both groups. The calving difficulty score was positively associated with calf birth weight in heifers (rs = 0.39) and cows (rs = 0.24). Binary logistic regression using both dam and calf data indicated that the ratio of front hoof circumference of the calf to the maternal intrapelvic area provided the best predictor of dystocia (calving difficulty score = 4 or 5), with sensitivity = 0.50 and specificity = 0.93 at the optimal cutpoint for the ratio (>0.068 cm/cm(2)). Determining the ratio of calf front hoof circumference to maternal intrapelvic area has clinical utility in predicting the calving difficulty score in Holstein-Friesian cattle.
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    • "Also, small pelvic dimensions tended to cause higher difficulty scores. Donkersgoed et al. (1993) assessed the repeatability (accuracy) of obtaining pelvic measurements between and within veterinarians and found they were imprecise. Their average repeatability was 40 percent which compares to 85 to 95 percent reported from studies in Missouri and Ohio. "
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    ABSTRACT: Calf deaths caused by dystocia (calving difficulty) result in a $600 million annual loss to U.S. beef producers (Bellows and Short, 1994). Therefore, methods to reduce dystocia must be investigated, understood, and utilized to decrease the incidence and degree of calving difficulty. A review of early research was presented at the 1989 Range Beef Cow Symposium at Rapid City (Deutscher, 1989) indicating the major cause of dystocia in first calf heifers was a disproportion between the size of calf at birth (birth weight) and the cow's birth canal (pelvic area). A pelvic area/ birth weight ratio developed in Nebraska was suggested as a method to estimate the size of calf a heifer could deliver without assistance. At the 1993 Range Beef Cow Symposium in Cheyenne, Dr. R. A. Bellows presented an extensive overview of research conducted at Miles City on numerous factors affecting calving difficulty. He concluded the following: 1) high calf birth weights were the main cause of dystocia, 2) dam pelvic area must be adequate to deliver calf, 3) selection for pelvic size will increase frame size and calf birth weight, 4) low nutrition will not reduce dystocia, 5) maternal uterine environment affects calf birth weight, 6) exercise during gestation did not affect dystocia, 7) early obstetrical assistance increased calf survival and dam subsequent pregnancy rate, and 8) hormones of calf and dam are involved in calving difficulty. This paper will not review all the above factors but instead will try to expand on the most important and will summarize the latest research on dystocia. It will also recommend some strategies for selection and management of heifers and bulls to reduce calving difficulty.
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