Sheep - AgRIS

The udder becomes firm and enlarged in pregnant ewes. A rectal probe cna be used to
palpate the uterus of ewe from about 70 days of pregnancy and is reliable when used by an
experienced operator (Plant, 1980).
Richardson (1972) reviewed sophisticated methods of pregnancy diagnosis and she
found over 80% accuracieds by vaginal biopsy, ultrasonic foetal pulse detection and
radiography. The foetal pulse detection is more practicable and is reviewed by Thwaites (1981)
and Wani (1981). This method can accurately predict whether or not an ewe is pregnant if used
after 60 days of Pregnancy (Aswad et al., 1976; Wani and Sahni, 1981) and the rate of lamb
heart beat can be used to predict the date of lambing.
Trapp and Slyter (1983) reported that ultrasonic scanning instruments developedto measure
carcass fatness, when used between days 69 and 112 of pregnancy, gave an accuracy of
pregnancy diagnosis of about 90%.
By laparotomy, pregnancy can be detected by as early as 30 days by skilled workers
(Pacho, 1973).
If the date of breeding is known, an analysis of plasma progesterone, 17 days later will
determine whether ewe is pregnant or not (Robertson and Sarda, 1971). For lactating ewes,
progesterone levels in the fore milk can be used to diagnose pregnancy (Ayalon and Shemesh,
1979).
7. 3.7 Parturition
The act of parturition is termed as lambing in ewe. Normal parturition consists of
expulsion of normal viable foetus from the uterus through maternal passage by natural forces
alone at a stage when the lamb is capable os independent existence (Kaushish and Arora,
1974b). It is difficult to predict the exact day of parturition in Nali sheep by studying the
antepartum blood cholesterol content. (Kaushish and Arora, 1974a).
Time of parturition
The time of parturition is one of the most critical periods in the life of ewe. During this
process, the ewe could possibly be injured and future reproduction efficiency be impaired
temporarily or permanently. The distribution of births appears to vary with the breed of the ewe
and the management system (Kaushish et al.,1973; Younis and EIBaboory, 1978; Tomar,1979;
Bhaik and Kohli, 1980). Highest number of lambings took place between 3 and 6 a.m. and 3
and 6 p .m. (Kaushish et al.,1973) in some native breeds and their crosses whereas, maximum
(40.0 percent) lambings took place between mid night and 6 a.m. in Russian Merino ewes
(Kaushish and Sahni 1975).
Signs of parturition
The symptoms of the onset of parturition consist of changes in the birth canal, progressive
extensibility to permit safe passage of foetus, and hypertrophy of the mammary glands. The
vulval lips become resilient and oedematous, two to six times their nonnal size. The ewes
usually lay on the right side streching the hind legs as far as possible, especially during
contractions and frequently showed upward turning of lips. Frequent grinding of teeth were
also observed. About 6 to 8 h before the expulsion of foetus the vulval labiae were about 0.5
cm a part and this distance increased to 1.0 cm about one hour before parturiton. The
respiration rate increased about half an hour before the appearance of water bag (Kaushish
andArora, 1974b).
Process of parturition in sheep
The process of parturition has been studied in detail by Tiwari et al. (1969a) and Kaushish
(1971) Table 7.3. The time taken for the completion of parturition was longest in Mandia x Nali
and shortest in Lohi. The post service gain in weight of dam was negatively correlated with the
time taken for the second and third stages of the parturiton (kaushish and Arora, 1974b). The
duration of sequence of events in the second stageofparturiton has also been studied in detail by
them (Kaushish and Arora, 1 974a).
Table 7.3 Duration of different stages noted in the process of parturition
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