Predicting parturition in the ewe from the pattern of uterine
motility
J.E. Wolff, P.M. Dobbie
Ruakura Animal Research Station, Ministry of Agriculture and
Fisheries, Hamilton
Proceedings of the New Zealand Society of Animal Production.
1984, 44: 15-18
Mature ewes, 110 to 125 days pregnant, had catheters surgically
implanted into maternal and foetal blood vessels and electrodes sutured
to the myometrium. Electromyographic (EMG) signals were amplified,
rectified, integrated and recorded. Between 2 and 12 days before
parturition, the EMG pattern comprised bursts of activity that lasted
6.3 ± 1.5 (SD) min interspersed with periods of quietness that lasted 30
± 13 min. Some 5 to 24 hours before delivery, a change in the EMG
signal was noticeable with shorter, more frequent bursts of activity and
a rise in the fraction of time occupied by activity from ~0.1 to >0.2.
During labour this fraction rose to ~0.5 with regular 1 to 2 min bursts
of activity interspersed with short (~1 min) periods of rest. Thus the
EMG can indicate impending delivery of catheterised lamb. Surgical
intervention produced a negligible reduction in gestation length from
147 ± 2 to 146 ± 1 days but a serious reduction in birth weight from 4.6
± 0.8 to 3.7 ± 0.6 kg.
Keywords: NZSAPAB;
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