Methods of Preg Testing

  • Farmer Observations

     

    1. Return to oestrus
      The close observation of cows is a reasonably reliable indicator of pregnancy status in small herds ( <100 cows) with an operator who knows the cows very well. However up to 10 % of pregnant cows can show some sign of heat during pregnancy and empty cows don't always show heat.

       

    2. Ballottement of the abdomen
      In the late stages of pregnancy ( >6 months), the foetus may be palpable through the right flank. This is unreliable in large frame cows or cows in heavy condition.

       

    3. Milk production
      Udder development in heifers is a reasonably reliable sign of pregnancy from 4-5 months of gestation.
      Empty cows often milk better than their pregnant herd mates. This isn't always reliable due to individual cow differences, but may indicate cows to check before drying off.

       

  • Rectal Palpation

    Performed by a skilled operator, rectal palpation is very accurate. Pregnancy can be confirmed from 6 weeks (later in fat cows), and the pregnancy can be aged. The accuracy of ageing depends on the skill of the operator and the stage of pregnancy.
    There is great variation in the facilities and subsequent ease of use of manual preg testing between farms.

     

  • Milk Testing

    If combined with herd production testing, the use of milk testing can be very convenient

     

    1. Oestrone Sulphate
      This test is quite good at detecting pregnant cows that are more than 5 months pregnant ( 98% ), however empty cows should be checked manually before being culled.

       

    2. Progesterone
      This test is quite good at accurately detecting empty cows ( ~ 90 %), but not very good detecting pregnant cows ( 30 - 35 % of diagnosed pregnant cows will be empty). This test is not used much in Australia or overseas.

       

  • Ultrasound Testing

     

    1. Flank Ultrasound
    2. Rectal Ultrasound
      A video display shows what is beneath a probe placed in the rectum. Performed by a skilled operator, ultrasound is very accurate at detecting pregnant cows. Ageing of pregnancy in the early stages (3 - 14 weeks) is possible but takes considerably longer than a 'Yes' or 'No'. Empty cows should be checked manually before being culled. Well prepared facilities are required.