Synchronising cows for reproduction is a frequently used management practice in dairy herds.
Why should you use synchrony programs?
- Easier heat detection: Heat detection aids such as scratchies and tail paint tend to be more reliable when many cows are showing heat at the same time. Cows showing weak or subtle signs of heat (oestrous) may be able to be detected more easily when many cows in the group are also showing signs of heat.
It is important to remember that some synchrony programs have a fixed time for insemination and do not require heat detection for the first insemination. However, good heat detection after the initial insemination can be a critical factor to achieve overall good herd reproductive performance.
Accurate observation and application of heat detection aids are important for the full duration of the AI period.
- Earlier detection of non-cycling cows: Synchrony programs involving heat detection can allow earlier detection of heat during the AI period. This means that non-cycling cows to be identified and therefore treated earlier. Pre-mating heat detection can also work well for some herds.
Any cow that has not displayed a heat by day 21 into the mating period should be examined by a vet. Delaying examination of these animals will have a negative impact on economic performance of the herd.
- Tighter calving pattern: Synchrony programs can result in simultaneous mating of cows over a shorter time frame which can help tighten the calving pattern. The earlier cows calve, the more likely they are to get back in calf at the subsequent mating period.
- More heifer calves born early: Early-born heifers have the advantage over later-born heifers in that they are more likely to achieve target weights for joining. Having a good replacement rate of heifers allows a greater ability to selectively cull cows with problems.
- Efficient use of labour: On many farms, having a tight calving pattern allows more efficient use of labour and better observation of calving cows. Transition feeding is also easier to organise with groups of cows calving at a similar time.
- Artificial breeding in heifers: Synchronising heifers to calve earlier than the adult cows can improve reproductive performance in the next mating period. As well as reducing the number of bulls required, artificial breeding of heifers can utilise sexed semen which can increase genetic gain.
Synchronising allows more efficient planning of treatment and insemination of heifers without the need for constant heat detection. This is useful when heifers are not close to the dairy.
Why shouldn’t you use synchrony programs?
Synchronising cows or heifers is not a silver bullet for an extended calving pattern.
Synchronising may be part of the solution to the problem but there are many other aspects to consider.
You should discuss the benefits and costs of synchronising with your vet before deciding if it is the best option for your herd.
Synchronising alone is unlikely to help if:
- Cows are only recently calved.
- Cows are in poor condition and are not cycling.
- Heifers are poorly grown and are well below target weight.
- There are limited resources to handle a large number of cows and heifers calving over a short time in the future.
There are many different types of synchrony programs, utilising different reproductive hormones and with variable degrees of intervention.
The expectations also differ, and it is important to discuss the options with your vet well before the planned start of mating.
Dr Gemma Chuck works for Apiam Animal Health in the dairy operations team where she writes technical service programs for farmers and vets.