The period from the date of conception to the day of parturition is called "gestation period" and the condition of the female of carrying the foetus during this period is called "Pregnancy".
"The period of pregnancy is the duration of time which elapses between conception and parturition".
Importance of Pregnancy Diagnosis:
Whether animal is pregnant or not is directly related to economy of dairy management Pseudo-pregnancy may lead to loss of valuable time period in the life of animal.Pregnant animals need to change their feeding schedule as well as the management from early stage. An early detection of pregnancy becomes an indispensable job for herd owner.
Methods of Pregnancy Diagnosis:
Signs of Pregnancy – exhibited and and detected extrenally.
Symptoms of Pregnancy – per rectum / vaginum examination.
- Laboratory Tests – Presence of certain hormones tested in laboratory.
A. Signs of Pregnancy:
Cessation of Oestrus cycle.
Tendency to fatten.
Gradual drop in milk yield.
Gradual increase in weight
Increase in size of udder.
Waxy – appearance of teats in last month of pregnancy
B. Symptoms of Pregnancy:
This clinical diagnosis of pregnancy is most convenient and reliable method in which the examination of genitals can be done by the expert having adequate knowledge in anatomy & physiology of the livestock. The examinations can be done by two systems.
1. Per rectum examination of ovaries, uterus: The palpation of uterus per rectum, during early and mid-gestation periods, can draw positive conclusion by detecting characteristic changes that take place in uterus & uterine arteries.
Ovaries: The corpus leteum of pregnancy persists in ovary at its maximum size throughout gestation period. It is firm. Rounded at top & slightly elevated from surface of ovary. Ovary can be examined from 10 days of service up to 3 months of pregnancy.
2. per vaginum Examination: If vagina examination during pregnancy by means of a speculum, wall appears dry and wrinkled. During pregnancy the secretion of cervical glands becomes gelatinous & tough forming a plug for sealing the canal. The seal develops on 60th day.
C. Laboratory Test:
1. Use of ultrasonic devices: Tested with the help of devices working based on principles that sound waves develop due to heart beats. Foetal movement & reflected back at an altered frequency. It can be tested 30-35 days of pregnancy.
2. Progesterone assay: Progesterone level estimation by using radio immune assay can be done in both milk & plasma of pregnant animal with standards of non-pregnant animals.
3. Pattern of Vaginal Smear: In this method, vaginal smears stained & fixed and visible cells are classified and inference is made, however no popular method due to lack of accuracy.
4. Immunological Techniques: In this, serum from pregnant animals tested which shows containing a factor "early pregnancy factor" (EPF). EPF can be detected as early as six hours after fertilization. This is sensitive test with accuracy, early pregnancy can be detected.
5. Barium chloride test: When 5-6 drops of 1% barium chloride solution is poured to 5 ml. of urine clear white precipitate is formed in non-pregnant cows. While added to urine of pregnant cow, the increased content of estrogen and progesterone of urine prevent formation of any precipitate. Test is 95 – 100 % accurate, takes less than 3 minutes, give correct results 31-210 days after fertilization.
6. Pregnant mare serum test (PMS): This test is presently applicable to mares only. It is conducted by using 10 ml blood serum collected from mare between 50-85 days after fertilization. This serum injected into there vein of mature, non-pregnant female rabbit which has been isolated from all male rabbits for at least 30 days. Positive test shows dark red follicles in the ovaries of rabbit 48 hours after injection.
7. Scanning: The pregnancy can be easily diagnosed by the equipment called ‘oviscan’ in sheep, cattle, horses & dogs. The equipment helps to establish pregnancy within 30 days of fertilization in sheep.