CHARACTERISTICS OF FETAL HEART-RATE CHANGES DURING THE EXPULSIVE STAGE OF BOVINE PARTURITION IN RELATION TO FETAL-OUTCOME

Objective-To characterize fetal heart rate (FHR) patterns of nonacidot ic (N-AC) and acidotic (AC) calves during the expulsive stage of partu rition. Animals-32 carves born to heifers, either unassisted or by mod erate traction. Procedure-Cardiotocograms (CTG) evaluated qualitativel y (visual) and quantitatively by a moving window technique (width 10, shift 5 minutes) for baseline FHR, variability, and periodic alteratio ns (accelerations and decelerations). Results-Significant differences were apparent between increase in baseline FHR of N-AC and AC carves; change in FHR (Delta-FHR), taking into account individual FHR, is a mo re discriminating parameter. The predominant reaction to uterine contr action is a decrease in FHR; variable decelerations were the most comm on type in both groups, and late decelerations were seen only in AC ca lves. Additional characteristics of variable decelerations were more f requently seen in AC calves. Conclusions-CTG parameters during expulsi on can discriminate between AC and N-AC calves, but specific character istics are not exclusively restricted to AC or N-AC calves. Clinical R elevance-CTG recordings during bovine parturition in cattle provide in formation on the fetal condition and can be used in the future to stud y the effects of medication and manipulations to the fetus.