Several methods are available to determine if a cow or heifer is pregnant.
If oestrus signs are not observed around 3 weeks after service or insemination, the cow is generally assumed to be pregnant. However, even if oestrus detection is good, not all of these cows will be pregnant. On the other hand, up to 7% of pregnant cows will show some signs of oestrus during pregnancy. Insemination of these animals may result in embryonic or foetal death.
More reliable methods for detecting early pregnancy in cattle are:
For details click on the different methods.
|Technique||Early testing||+ve diagnosis accuracy||-ve diagnosis accuracy|
|Early Conception Factor||++++||+||+|
Advantage: immediate result enabling early treatment of non-pregnant cattle.
Accuracy: depends on the experience of the practitioner and can reach 95%.
Rectal examination is usually carried done between 35 and 65 days post AI.
Early pregnancy diagnosis
Based on a combination of the following:
Diagnosis in later pregnancy
Stage of pregnancy
Fremitus A.uterine media
Common reasons for errors in rectal palpation
Rectal palpation is widely used and considered a safe method for pregnancy diagnosis in cattle. Nonetheless early or inappropriate palpation of the amniotic vesicle may damage the embryo and cause embryonic mortality.
The progesterone secreted by a functional corpus luteum between 18 and 24 days after service or insemination is an early indication of pregnancy. It can be assayed in milk or plasma. Optimal assay time is 24 days after service or AI, this eliminates the possibility of long oestrus intervals which might result in false positives.
The sensitivity (i.e. accuracy in detecting pregnancy) of the cow-side milk progesterone (EIA) test was 93.1% in a study by Pieterse et al. (1989). However,specificity (i.e. accuracy in detecting non-pregnancy) was only 39.3%. A large number of non pregnant may thus be diagnosed as pregnant.
Common reasons for errors in hormone measurements
Recently available tests detect so called early conception factor (ECF) or pregnancy-associated glycoprotein in blood samples. They are reported to detect the pregnancy-associated glycoprotein within 48 hours of conception.
Because of the high incidence of embryonic mortality this test should be treated solely as an indication of conception. Pregnancy should be confirmed later by rectal or ultrasound examination.
Pregnancy examination using ultrasound
Early identification of non-pregnant cows post breeding improves reproductive efficiency and pregnancy rate in cattle by decreasing the interval between AI services and increasing AI service rate.
Real time (B-mode) ultrasound is a reliable and relatively simple method of diagnosing pregnancy as early as day 26.
An accuracy of over 99% can be achieved, enabling fertility problems to be identified rapidly.
When both factors are optimised, the speed of ultrasonography can approach that of rectal palpation, while exceeding palpation in the amount of information gathered from each animal. The main advantage of scanning is that it can give an accurate diagnosis earlier than rectal palpation.
Early pregnancy diagnosis and embryonic loss
Pregnancy can be detected earlier with ultrasound compared with rectal palpation. The rate of detection of early embryonic loss is thus also higher.
10 to 16% of cows diagnosed pregnant at 28 days post AI, experience early embryonic loss by 56 days post AI. Cows diagnosed pregnant at 28 days post AI using ultrasound should be scheduled for a subsequent examination around 60 days post AI, when the rate of embryonic loss per day decreases dramatically.
Characteristics of the conceptus visible via ultrasound
|Characteristic||First day detected|
|Embryo proper||20.3||19 to 24|
|Heart beat||20.9||19 to 24|
|Allantois||23.2||22 to 25|
|Spinal cors||29.1||26 to 33|
|Forelimb buds||29.1||28 to 31|
|Amnion||29.5||28 to 33|
|Eye orbit||30.2||29 to 33|
|Hindlimb buds||31.2||30 to 33|
|Placentomes||35.2||33 to 38|
|Split hooves||44.6||42 to 49|
|Foetal movements||44.8||42 to 50|
|Ribs||52.8||51 to 55|