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Peter Younis

We are often asked about the benefits, costs, workload or complexity of herd oestrus synchrony programs. There are, as most farmers know, a multitude of options, each with pros and cons. The answer is that each program is very different and may or may not be suitable on different farms for a variety of reasons.

This article looks at a real life case study and compares the effect on herd dynamics and fertility of some different approaches.

Ashley and Michelle Gristede farm at Port Campbell, and they have very kindly agreed to share their experiences.

Ashley and Michelle have a split calving holstein herd. Each mating involves approximately 350 cows. This includes around 70 carryovers and 70 to 80 1st calvers. No bulls are used in the milking herd.

Prior to commencing the ovsynch program the herd had slightly better than average fertility, cows have a transition program and calve in good Body Condition Score (BCS), and do not lose significant weight. Facilities and cow ID are excellent, and all treatments are carried out on a platform during milking on the rotary dairy.

In the first year of ovsynch the treatments were administered by a veterinarian, and in all other years the treatments were administered by Ashley.

Herd programs

Ashley and Michelle used the following programs:

Autumn 2016 – Ovsynch program – Trialled a new approach where half of the synchrony cows were given the traditional single dose of PG and the other half were given 2 doses of PG, 12 hours apart.

Spring 2016 – Single modified why wait PG program – Cows are mated for 1 week then all eligible cows receive a single dose of PG

Autumn 2017 – Ovsynch program – All cows received the 2 doses of PG

A local research project conducted by Joey Rheinberger has now confirmed that there is a significant increase in conception rate by using the 2 doses of PG in an ovsynch program.

Ovsynch + 2 x PG program

The insemination pattern for the Spring 2016 PG program and the Autumn 2017 ovsynch program is as follows.


Let’s look at the Spring 2016 year first. This is typical of many herds in the region. Six week In Calf Rate (ICR) is a bit better than the average (50%).

Conception rate is around average and the submission rate is better than we commonly see. I suspect that this is due to the relatively tight calving pattern in the herd, the good BCS and heat detection practices. It is important to note that the mating period is 69 days. 10 weeks is a relatively short mating length and in many herds, will mean that there will be a sizeable number of empty cows. The empty rate of 30% is a good result in this herd.

Now let’s look at the Autumn 2016 and 2017 years. The main effect of the synchrony program has been to increase the number of cows that conceive in the first 6 weeks of mating. In fact, a considerable number of these conceived in the first 2 days! The 6 week ICR now puts this herds fertility in the top 25% of herds.

Conception rate has remained very good. In fact, better than I would normally expect with an ovsynch program. The result in 2017 has been exceptional. It is possible that the use of 2 doses of PG has contributed to this. On the other hand, there were 30 doses of sexed semen used where the conception rate was 30%.

Note that the submission rate was not 100% as not all cows were eligible for the ovsynch.

The number of days that it took to have 50% of the herd in calf has been reduced by around 10 days. That translates in to a significant increase in milk supply.

Of significance is that the length of mating has been reduced in both the ovsynch years, without affecting the empty rate.

Well planned program

This is an example of a well planned program in a herd where there are excellent facilities; it is easy and pleasurable to administer the treatments. We have clear guidelines for which cows to include and other important aspects of herd fertility are constantly being addressed. These include adequate well grown heifers, management of BCS, a transition program, good heat detection and insemination practices.

Ashley and Michelle commented that the ovsynch suits them particularly, as it significantly reduces the amount of time that Ashley spends standing on the platform heat detecting.

When asked how they cope with calving so many cows at the same time, Ashley responded, “The calving pattern for the ovsynch in our first season actually spread out well. We had 132 that held to the first insemination. The maximum number of cows calving on any one day was about 18 and in fact by the time the actual planned calving date came, we only had 10 left to calve”

This program is not suitable for every herd. Call Farm Services 1300 838 700 and we will be very happy to discuss the pros and cons with you, and help you determine what is the best approach for your herd.