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Collecting Scrotal Circumference Measurements

Scrotal circumference measurements taken on bulls between 300 and 700 days of age are used to calculate Scrotal Size EBVs within the TransTasman Angus Cattle Evaluation (TACE).

Recording scrotal circumference measurements

Scrotal circumference measurements should be recorded by pulling the testes firmly down into the lower part of the scrotum and placing a measuring tape around the widest point (as per the photo below). Scrotal circumference measurements can be taken by anyone. They do not need to be taken by an accredited technician.

When measuring scrotal circumference, remember:

A variety of scrotal circumference measuring devices are commercially available from agricultural supply stores or organisations such as the Australian Cattle Veterinarians. Metal scrotal measuring tapes are more reliable than cloth tapes as they are not prone to stretching.

When should scrotal circumference measurements be collected?

TACE can analyse scrotal circumference information from bulls that are between 300 – 700 days of age when measured. Subsequently, it is essential that scrotal circumference information is recorded when bulls are within this age range.

It is recommended that scrotal circumference is measured when bulls are reaching puberty, which will vary according to seasonal conditions and the maturity pattern of the animals being measured. In the majority of cases, the optimum time to record scrotal circumference measurements for TACE is when bulls are being weighed at 400 days.

  • While more than one scrotal circumference measurement can be recorded for an individual animal, TACE is only analysing the first measurement for each bull at this stage. Subsequently, it is only necessary to record one scrotal circumference measurement on each bull for TACE.
  • Scrotal circumference measurements should be collected for all bulls in a mob. Only recording scrotal circumference measurements for a subset of bulls is of no value and can lead to biased Scrotal Size EBVs.
  • A management group should be recorded for any bulls or group of bulls that have been treated differently or exposed to significant non-genetic influences prior to measurement that may affect their scrotal circumference. For example, the scrotal circumference measurements for bulls given a supplement should be recorded in a different management group to those without a supplement. Consideration should also be given to variations in pasture quality, stocking rates, water quality, etc.
  • A management group should be recorded for any bulls that have been joined prior to measurement.
  • Scrotal circumference measurements should be recorded for all bulls in a mob on the same day. TACE will not directly compare scrotal circumference measurements collected on different days.
  • Scrotal circumference measurements should be collected when bulls are in as large a group as possible. Consequently, try to collect scrotal circumference measurements before any of the bulls in a management group are treated differently. For example, before some bulls are joined or bulls are separated into smaller groups for ease of management.


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