P4Gold, Timed AI and Synchronisation Protocols

There are many different strategies for managing herd fertility in dairy herds. From different calving systems to synchronisation and timed artificial insemination, the options are many. P4Gold is a valuable tool, regardless of what system is in place.

What is Timed AI?

Timed AI is usually used in conjunction with synchronisation programmes. It involves inducing ovulation in cows using a combination of hormonal and non-hormonal treatments, and then inseminating at a fixed time point, regardless of heat behaviour which may or may not be present. The main aim behind it is to remove the need for heat detection. Heat detection can be expensive, time-consuming, and prone to human error as it is often based on behavioural observation.

How Does Synchronisation Work?

Synchronisation treatments are usually injectable.
Synchronisation treatments are usually injectable.

Synchronisation is when cows are treated to force their oestrous cycles to line up. If successful, this means that all the cows in the group will go into oestrous at the same time. cows are inseminated together, and the cows will calf around the same time. While rarely 100% successful, these programmes can make managing dairy herds easier and create fixed timelines. This is often especially useful for extremely large herds.

One of the most widely used synchronisation protocols is OvSynch, which was first pioneered by scientists at the University of Wisconsin-Madison in the USA. This protocol uses gonadotrophin-releasing hormone (GnRH) and prostaglandin (PG). GnRH is a hormone which induces ovulation. It is the first step of synchronisation and all cows in the group receive a dose. As a result, the cows will hopefully ovulate. PG is not a hormone itself, but has a hormone-like effect. A week after giving GnRH, cows receive a dose of PG. This causes the corpus luteum which has formed to regress, lowering progesterone levels. This step catches any cows which didn’t ovulate with the first administration of GnRH. Three days after this treatment, cows receive another dose of GnRH to synchronise their ovulation.

After this treatment, the majority of cows will have synchronised their oestrous cycles. As a result, 16-24 hours after the last GnRH treatment, the cows are all AI’d. This happens even if they are not showing any heat behaviours.

How Can P4Gold Help?

As P4Gold is primarily used as a heat detection aid, it may not seem useful in a situation where heat detection is not important. However, that is not the case! P4Gold is a progesterone test, and while it is a useful tool to detect heat, it has many other uses.

In synchronisation programmes, timing is everything.
In synchronisation programmes, timing is everything.

In synchronisation programmes, while most of the cows will likely respond to the treatment, there will always be some that won’t. This can be due to fertility problems, such as anoestrous or ovarian cysts, or because by chance they were not in the correct phase of their cycle for the synchronisation to work. For these cows, inseminating after the synchronisation protocol would be a total waste of an AI straw.

Checking a cow’s P4 level on the day of insemination can tell you if she is one of these cows. If P4Gold shows a cow has high progesterone, she will not become pregnant from that insemination. As such, there will be less wastage of AI straws. If her progesterone is low, it is likely that the synchronisation worked, and insemination has a better chance of being effective.

Studies have shown that using a rapid progesterone test – in this case P4Rapid, the precursor to P4Gold – can accurately predict fertility outcomes. This can increase herd fertility, reduce wasted AI straws and help in fertility management.