Teagasc recommends that replacement heifers are bred with dairy artificial insemination (AI) because they are the most fertile animals in the herd and they have the highest economic breeding index (EBI).
Make sure to target your heifers with sexed or conventional dairy AI to maximise the rate of genetic gain in your herd.
Calving heifers at the start of the breeding season and in a short space of time, will not only allow them to produce suitable breeding stock for the herd, it will also maximise their chances of staying in the herd for longer and increase their lifetime productive performance.
One way to achieve this is through a successful synchronisation programme. This will increase the amount of heifers bred to AI and will minimise the workload associated with breeding maiden heifers – during a busy time of the year.
Synchronisation protocol for replacement heifers
Here is a sample synchronisation programme commonly used on farms – involving the use of prostaglandin (PG) and heat detection:
- Day 0: All heifers are tail painted or use scratch cards;
- Day 0-7: Inseminate any heifers that are observed in heat;
- Day 7: All heifers not inseminated are given an injection of PG and any showing heat are inseminated over the next three to five days;
- Day 17: Any heifers still not bred are given a second injection of PG;
- Day 20 and 21: Heifers are inseminated when observed in heat or receive fixed time AI at 72 and 96 hours after the second PG injection;
Following this, stock bulls can be let out to pick up any repeats.
This is just one of many synchronisation protocols used on farms; you should consult with a vet before implementing one for your farm.
It is important to note that synchronisation protocols work very well for heifers that have started cycling, but will not work in non-cycling heifers.
For heifers to begin cycling they must be old enough, at the correct target weight, be on a high plain of nutrition and be healthy by mating start date (MSD).