Back fat thickness

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The back fat thickness of dairy cows is determined in order to be able to make statements about the energy supply of the animals. With the BCS grades, it is one of the most important ways of determining the condition of dairy cows. It is the only non-invasive but objective option.

method

The thickness of the back fat is determined using ultrasound. The measurement is taken on the line connecting the ischial tuberosity and hip tuberosity , about a hand's breadth away from the ischial tuberosity. To ensure repeatability, the affected area is often shaved so that it can be found again safely.

Conclusions

1 mm measured back fat thickness (including skin) corresponds to around 5 kg body fat of a dairy cow. With the RFD as a determination method, measurements in different stages of lactation can be used to describe the rate of fat loss. The distance from the skin surface to the Fascia trunci profunda is measured by ultrasonography and given as the RFD in centimeters. It should be noted that the stated measured values ​​include the skin thickness of around 5 to 6 mm. The absolute amount of the ( subcutaneous ) fat layer lying under the skin is therefore lower by this value. The Fascia trunci profunda serves to define the border between the muscles and the fat layer. It appears on the ultrasound as a white (echogenic) line. According to studies by the LfL Bayern, there is a high correlation to the BCS grades.

Measurement problems

In addition to the deep fascia, there are other similar structures with which it can be confused. If the pressure from the ultrasound head is too high, the fatty tissue and muscles may shift.

Results according to Schröder and Staufenbiel

Back fat thickness measurements by means of ultrasound on around 46,000 dairy cows in 75 different farms yielded the following results:

- With a higher milk production, the cow's negative energy balance is stronger and longer than with average milk production.

- A decrease in the thickness of the back fat to a value below 10 mm leads to a decrease in milk yield.

- High-production cows should always keep a certain amount of fat. Otherwise, they can not build up sufficient reserves at the end of lactation and during dry periods .

- In the late lactation, less performing animals put on excessive amounts of fat.

- An RFD of 13 mm is considered the minimum in early lactation. This enables good fertility. In the dry period, the RFD should be between 22 and 24 mm.

- In the first weeks of lactation, the decrease in RFD should be less than 0.14 mm. Higher rates of decrease of the RFD indicate an excessive loss of body fat. This has threats to performance, animal health, and fertility.

- The energy balance situation and the RFD are in a close correlation with the milk protein content. A milk protein content of less than 3.2% indicates a strong energy deficit.

- In the case of intensive RFD acceptance, the rest time and the test time are extended .

- In order to be able to use the dry period to improve condition, the positive energy balance should be achieved after 100 days at the latest.

Web links

Individual evidence

  1. ↑ Rudolf Staufenbiel: Energy and fat metabolism of cattle with special consideration of the measurement of the thickness of the back fat . Habilitation thesis, FU Berlin 1992.
  2. ^ Walter Busch, Wolfgang Methling, Werner M. Amselgruber (eds.): Animal health and animal disease theory . Parey Verlag, Stuttgart 2002, ISBN 3-8304-4197-5 .
  3. ↑ See: Ulf Schröder, Rudolf Staufenbiel: Relationships between backfat Thickness, milk yield and fertility traits with resulting standard curves and their application in dairy herd management . In: WBC Hannover: Relationships between back fat thickness (RFD), milk yield and fertility in dairy herds . 2002.