Bull Service Heat Sync Protocol
Increasing conception rates and a tighter calving window should be on the minds of every cow/calf producer in the cattle industry. We follow a strict mineral program, use quality bulls and make sure our heifers are in breeding shape, but that doesn’t mean we aren’t always looking for ways to improve our operation. We’ve always used a bull service to breed our cattle, so I want to share about a heat sync protocol we’ve been following for a few years now. At the very end, look for a breakdown of our results from 2021 and 2022. My dad originally started researching this protocol for a little over two years before we decided to try it. After one trial year in 2021, we’ve followed it annually. A link to the original article can be found HERE.
Here is my disclaimer that I share frequently: I am not a licensed veterinarian. We are just normal producers, just like you, looking to make improvements where we can! I’d encourage each and every one of you to do your own research before making any decisions on your operation.
In a nutshell, you turn your bulls in on day “zero”, giving any heifer who is in heat on her own the chance to get bred. On day five, you give each heifer 2mL of prostaglandin. We use ESTRUMATE® (cloprostenol injection). On days 6-10, it helps heifers heat cycle at the same time. Prostaglandin won’t affect the pregnancies conceived those first 5 days.
Source linked HERE
Up to 2020, our breeding program was a 45 day window with no heat sync protocol. In 2021, we first tried the heat sync protocol on a 45 day breeding window. After seeing the results from 2021, we were confident in the protocol and shortened our breeding window to 30 days in 2022.
This protocol is not a “one size fits all” solution for increasing conception rates. It is something we have done in addition to other means of making improvements. We also have a quality mineral program and use Purina liquid accuration on some of our cattle.
Here’s some things to keep in mind if you want to try this
Body Condition Score
You must have enough bull power in your herd. Since most of them will be coming in to heat at the same time, your bulls’ will be working overtime. They need to be in good shape, and you should take into consideration the number of bulls being used. This should be done annually anyway, but I would recommend having your bulls semen tested and have a breeding soundness exam completed by your veterinarian prior to turning them in.
Weather
We live in Missouri. It gets HOT and HUMID here. Sometimes that weather can affect your bull's wanting to get up and go find a cow to breed.
It is CRUCIAL to give your shot of ESTRUMATE on day 5. The cattle that were bred on days 0-5 will not be affected by the prostaglandin at this stage in their pregnancy. However, any further past this and it will cause them to abort.
Common Questions:
Why did we want to try this?
Tighter Calving Window
As producers who market weaned calves, having a uniform group of calves the same age and weight usually pays off. We also market and calve out bred heifers, and sell heifer pairs. Having a shorter calving window makes for a quick work load and helps with labor efficiency. Calving heifers can be a daunting task as it is, and we believe it’s better to get it over with quicker, versus stringing it out overtime. This is a great selling point, too, when selling them as bred heifers. Our buyers are happy with a 30 or 45 day calving window. Personally, we pull the bulls completely out after the 30 or 45 days (whichever we are doing). That way there is no discrepancy on the calving dates. It’s common for them to calve early, or maybe a little beyond the set dates, but with pulling the bulls we can guarantee they won’t be calving all year long.
Increase early conception rates.
On days 6-10 of the breeding cycle, the heifers that received ESTRUMATE will be coming into heat within that time frame. Therefore, a majority of your calves will be coming sooner because they were bred sooner. This circles back to more even calves and a more efficient workload.
Why not artificially inseminate?
We just aren’t set up for it. A lot of our cattle are spread out, we don’t have the best facilities on each farm, and quite frankly, we didn’t want to have to go through the AI process of getting the cattle in the chute several times. Most of the time, it’s just my dad and I doing all of our cattle work. With just the two of us, running several hundred head through the chute several times on different farms is A LOT of work.
With this protocol, it’s one time through the chute and one shot. We wormed the heifers as we ran them though too, so we accomplished a few things at once. ESTRUMATE dollars out about $2/head. For us it’s a cheap way to hopefully make some improvements in our breeding stock.
As stated above, I am not a licensed veterinarian. Your local vet would be an excellent resource for any and all questions. Also, MERCK offers an “Ask the Vet” section on their website that is incredibly handy. Find it HERE.
RESULTS
Below, I break down the statistics and results of groups we followed this protocol on in 2021 and 2022. 2021 was our first year trying this protocol and after seeing the results, the following year we went down to a 30 day breeding window. When we were calving the 45 day heifers, a majority of the calves were coming within what would have been the first heat cycle. Stringing it along the rest of the 45 days seemed unnecessary. Hence, going down to a 30 day window the following year. This gave us an even tighter calving window!
Again, we pull the bulls on either the 30th or 45th day, whichever we are doing. We ultrasound 45 days after pulling the bulls. It’s not usually on the exact 45th day, just depends on weather and our schedules.
2021:
We purchased our replacement heifers in March of 2021 and started them on Vitalix Breedback tubs and salt.
2 out of the 4 groups that we thought needed a little extra “oomf” received liquid accuration. This helped them gain some weight, hopefully to help them breed. 3/4 groups received the heat sync protocol.
2022
Heifers were purchased in March 2022 and started on Vitalix Breedback tubs and salt. 1/4 groups received Purina Liquid Accuration. 4/4 groups received the protocol.
Additional resources and sources linked below
Value of synchronizing bull-bred cows and first-calf heifers
ESTRUMATE IMPORTANT SAFETY INFORMATION
Do not administer ESTRUMATE to a pregnant cow unless abortion is desired. Severe localized post-injection clostridial infections have been reported; in rare instances infection has led to death. Women of childbearing age, asthmatics, and persons with respiratory problems should exercise extreme caution when handling ESTRUMATE. ESTRUMATE is readily absorbed through the skin and can cause abortion and/or bronchospasms; direct contact with the skin should be avoided, and accidental spillage on the skin should be washed off immediately with soap and water. For complete safety information, refer to the product label.
