Synchronisation can be useful in dairy cow management: study
Synchronisation of heifers is already commonly practised, with even the animals that have their calf early in the calving season likely to benefit and to remain in the herd longer, with a longer productive life.
The large-scale Moorepark trial on cows, the first of its type in Ireland to look at synchronisation of ovulation, included over 1,600 cows on eight farms. The work formed the basis of a PhD project carried out by Mary Herlihy, also at Teagasc Moorepark.
Synchronisation is costly (between €24 and €40 per animal), and time consuming, and is likely to be appropriate only for some cows.
“It is certainly not a magic solution, but when used strategically it can assist farmers to improve their calving pattern,” says Teagasc Moorepark researcher Stephen Butler.
The benefits of a tight and early calving pattern are clear:
* Longer lactation.
* More time on grass during the lactation.
* A higher percentage of cows bred with AI.
* Management advantages when more cows calve within a shorter window.
* Better milk supply profile, potentially avoiding mid-season price penalties.
The Teagasc trial was designed so that cows assigned to synchronisation treatments were calved at least six weeks before AI. To ensure that late calving cows in the herd were included, three rounds of synchronisation were needed on each farm. The first round of synchronisation was carried out to facilitate AI of eligible cows on the first day of the breeding season (Apr 25). To be eligible to be served on this day, cows would have to have been milking since at least Mar 14 (42 days). The synchronisation protocols used took 10 days, meaning that, for this group of cows, the synchronisation protocols began on Apr 15. The cows were then served on Apr 25.
The second group of cows would be served with AI three weeks after the mating start date, on May 16, and the last group of cows three weeks later, on Jun 6, following the 10-day protocol on each occasion. Repeat heats from the first group would coincide with the synchronised heats for the second group. Similarly, repeat heats from the second group would coincide with the synchronised heats for the third group.
As expected, the same percentage of cows in each treatment were pregnant at the end of the breeding season, whether synchronised or not. But cows on the synchronisation treatments got pregnant earlier during the breeding season. On one treatment (CIDR-TAI), up to 40% of cows established pregnancy on the first day of the breeding season.
How can it work on farms? In normal farming situations, synchronisation is most likely to be used on a small number of problem cows, not the full herd approach used in the Moorepark trial. “If a farm has a good tight calving pattern with 90% of cows calving within six weeks, synchronisation isn’t required,” says Stephen Butler.
“But if cows are not showing heat, or are late calvers, it may help to improve the herd’s overall calving pattern.”
The process begins several weeks before the mating start date, with pre-breeding heat detection to identify cows that are cycling, and to allow prediction of when they will be on heat during the first three weeks of the breeding season.
If cows have not shown signs of heat during the period of pre-breeding heat detection, either they are not cycling, or they are cycling but are not showing behavioural signs (silent heat). Both of these types of cow are candidates for synchronisation.
Cows that are identified to be cycling during the pre-breeding period will be served as normal after being observed in heat when the breeding season has begun.
Cows not detected in heat and that are more than 32 days calves can be treated with CIDR-TAI, allowing insemination 10 days later.
A prescription is required from a vet to source synchronisation hormones. Great care is needed in applying the synchronisation.
Good handling facilities are essential to separate the cows that require treatment. It is vital that the correct cows get the correct treatment at the correct time.
Cows treated for synchronisation within the herd should be paint marked to allow for easy identification. Synchronisation can be used to accelerate the return of late calving cows to heat (although they must be six weeks after calving at the time of AI), which may mean they can remain in the herd rather than be culled.
But it should not be seen as a routine substitute for basic skills such as heat detection, having cows at the right condition score, and deciding if a cow needs to be culled.
