Author
|
Submitted to: Canadian Veterinary Medical Association
Publication Type: Proceedings Publication Acceptance Date: 7/1/1997 Publication Date: N/A Citation: N/A Interpretive Summary: This is a review of research results of genetic and environmental factors resulting in maternal influences on dystocia. Results summarized indicate selection for rapid-growth breeds results in increased dystocia. If heifers are to be saved for replacement females, their sires must be evaluated carefully for direct and maternal calving ease. Maternal behavior, as measured by docility, is heritable and calculation of breeding values for docility appears warranted. Acceptable percentages of dystocia, maximum neonatal survival, and optimum reproductive performance of the dam are dependent on adequate nutrition. Maternal-fetal disproportion at parturition is a major causative factor affecting dystocia. Recent research shows clearly there is an endocrine/metabolite aspect to dystocia with detectable circulating endocrine and metabolic concentration differences in dystocial dams 10 days prior to the actual event. Synchrony and patterns of the prepartum endocrine and metabolic cascade are important for normal parturition. Efficacy of relaxin treatment and use of pelvic measurements to minimize dystocia is controversial. Exercise during gestation had no effect on dystocia, but increased feed requirements. Early obstetrical assistance increased neonatal survival and calf weight gain from birth to weaning and improved subsequent reproductive performance of the dam. Technical Abstract: This is a review of research results of genetic and environmental factors resulting in maternal influences on dystocia. Results summarized indicate selection for rapid-growth breeds results in increased dystocia. If heifers are to be saved for replacement females, their sires must be evaluated carefully for direct and maternal calving ease. Maternal behavior, as measured by docility, is heritable and calculation of breeding values for docility appears warranted. Acceptable percentages of dystocia, maximum neonatal survival, and optimum reproductive performance of the dam are dependent on adequate nutrition. Maternal-fetal disproportion at parturition is a major causative factor affecting dystocia. Recent research shows clearly there is an endocrine/metabolite aspect to dystocia with detectable circulating endocrine and metabolic concentration differences in dystocial dams 10 days prior to the actual event. Synchrony and patterns of the prepartum endocrine and metabolic cascade are important for normal parturition. Efficacy of relaxin treatment and use of pelvic measurements to minimize dystocia is controversial. Exercise during gestation had no effect on dystocia, but increased feed requirements. Early obstetrical assistance increased neonatal survival and calf weight gain from birth to weaning and improved subsequent reproductive performance of the dam. |
