Pak Dairy Info - Parturition in Dairy Animals


Parturition

The process of parturition has been divided into 3 labour stages as detailed below:

Stage 1 Labour:

Cervical dilation takes place
Uterine contractions increase because the quiescent influence of progesterone is fading
Uterine contraction help fetus move towards birth canal
Chorioallontoic sac pressure induces cervical dilation
Cervix is dilated 7 to 15 cm in diameter by the end of stage 1 labor
Increasing restlessness, circling behavior, copious mucus flow from the reproductive tract, increased defecation and urination, high respiration rate, and slacking pelvic ligaments are all events associated with stage 1 labour that usually lasts from 2 to 12 hours
The duration of stage 1 labor can be influenced by breed and parity of the buffalo/cow.

Stage 2 Labour:

This stage begins as the fetus enters the cervix
Uterine contractions increase in frequency and develop a rhythm. Labor pains occur as clusters of 5 to 8 contractions and last for about 1 minute separated by 2 to 3 minutes rest periods
Stretching of birth canal leads to release of oxytocin, its concentration increases 30 to 50 times during the passage of the calf through the cervix. Abdominal contractions occur in combination with clusters of uterine contractions to propel the fetus through the cervix.
Pressure from the head and shoulders of the fetus passing though cervix causes the final phase of cervical dilation
The fluid filled amnion and chorioallontois protects the fetus from the forces exerted by the incompletely dilated cervix.
Premature rupture of chorioallontois (water bag) results in temporary cessation of abdominal contractions because the space occupied by the fetus is suddenly reduced.
The feet of the fetus normally appear about 3 minutes after the fetus enters the cervix
In problem cases where assistance is required, this phase can prolong. Since expulsion of the fetal head and shoulders requires further dilation of cervix. Therefore progress at this point is slower
About 15 to 40 minutes after the appearance of feet and depending upon the size of the fetus, intensity and frequency of contractions increase. Hereafter, the fetus is delivered within about 30 minutes
Animals with a higher incidence of dystocia usually require more time from appearance of water bag to the appearance of the feet, the appearance of the feet to the delivery of the head and then to the delivery of the calf. The normal course of the stage varies from 45 minutes to 3 hours again depending on breed, size of the fetus and parity.

Stage 3 Labour:

The third stage of labour covers the period during which expulsion of fetal membrane take place. It usually take 4 to 6 hours.
Fetal membranes not expelled in about 12 hours are generally termed as retained placenta. Animals giving birth to male calves retain placenta for longer time. Dystocia cases lead to increased incidence of retaned placenta 2 to 3 times. The physiological mechanism for this increase is unknown.