Does oestrus observation work? - Success control
As in many aspects of farm management it is also worthwhile from time to time to verify objectively the subjective impression on how well oestrus observation is working in daily operations.
There are a few signals that could indicate weaknesses in oestrus detection:
- Only a few fresh-lactating cows (< 45 days in milk) are identified as in oestrus.
- Involuntarily they have a long average rest period – longer than you intend.
- Many cows have to be re-inseminated after more than 42 to 46 days.
- Many non-pregnant cows are found during pregnancy testing.
Oestrus detection rate
In order to ensure the quality of oestrus observation is objective, fertility professionals recommend the oestrus detection rate be determined over 24 days:
- You make a list of all animals who calved longer than 45 days ago but which have not yet been inseminated.
- Over the next 24 days you delete each cow that you have seen in oestrus.
- Then you calculate how many animals in this period you have identified at least once as in oestrus.
A satisfactory oestrus detection rate starts at 80%.
Ueli’s farm has 40 cows who calve seasonally. On 5 January 25 animals have still not been inseminated but calved more than 45 days ago. Ueli notes the names on a shed list. By 29 January he has identified 13 of these animals as in oestrus and has deleted them from the list. He calculates (13 x 100)/25= 52.
He has therefore an unsatisfactory oestrus detection rate of 52%.
Most frequent mistakes
What are the most frequent mistakes when your oestrus detection rate is too low?
- You do not observe at regular intervals during the day
- You observe for only a short period
- You only observe during shed periods
- You and others who are observing oestrus on the farm do not arrange things correctly between each other.
- You do not note down your observations correctly
- You do not detect the oestrus signals or you do not interpret them correctly
Oestrus monitoring tools
Systems differ in their use, acquisition costs and uniqueness. However, they amortize quickly because the commercial consequences of a missed oestrus detection are concealed but horrendous. For example, in Switzerland the talk is of 350 Swiss Francs incurred in costs per missed oestrus.
Tools that may be used to support oestrus observation include color markings and electronic systems such as pedometers, activity meters or continuous video surveillance.