Synchronising heifers isn’t for everyone – it’s a lot of extra work at a busy time of year. But the economics of getting extra replacement heifer calves from your highest BW animals and increased days in milk do make it worthwhile, if you decide to do it.

There are various synchrony programmes available. Most of the options have been around for years, but the new Modified 5-day Cosynch programme shows significant improvements over the standard heifer CIDR synchrony programme, the 7-day Cosynch.

Looking at the table and graph below, there is an increase in conception rate to AI from 45.5% with the standard programme to 62% with the modified 5-day Cosynch.

The downside (there is almost always a downside) is 5 yardings during the 10 days of the programme, compared to 3 yardings for the old programme. There is also an increase in cost for the extra 2 PG injections. The table below shows the timing of both programmes.

There are a couple of other options for synchronising heifers that don’t involve CIDRs. They are:

• Single PG injection, with AI to observed heat. Assuming all the heifers are big to enough to be cycling, a single prostaglandin injection will bring approximately half of them on heat, 48-72 after the injection. You’d expect to get around 25% in calf, and you would need to tail paint and observe heats for a few days.
• Double PG injection, 10 days apart. The heifers that don’t respond to the first injection should respond to the second one, and the ones that did respond will be at the correct point in their cycle to come on heat again. In this scenario, you would expect to mate 90% of the heifers, and get 45-50% of them in calf. Again, there’s time and hassle involved, with tail painting and observing heats. Most people go for a CIDR programme despite the increased cost involved, because fixed-time AI is so much easier to organise.

If you’re thinking about synchronising heifers, give your vet a ring. We can help you decide which option is likely to work best and be most cost effective for you.