The author is a partner in the Maria Stein Animal Clinic, Maria Stein, Ohio.
Pregnant with twins," I announced as I scanned cow 13478. Sam dutifully entered the information in his handheld device, but the slump of his shoulders was more dramatic than if I'd called 13478 open.
Even though only half of the cows diagnosed with twins at 32 days carry them both to term, and there are several potential outcomes, only a few of them are good. One good outcome is that one of the twins would be resorbed and 13478 would have a normal single birth. Another is that twins would be carried to term, born alive, and 13478 would have no metabolic issues postpartum. Yes, that does happen, more often on some farms than others.
The bad outcomes include resorption of both embryos or abortion late enough that it isn't viable for 13478 to be rebred. It would also be bad if 13478 had significant postpartum issues leaving the herd during the first 60 days in milk. This may not pay back her dry period investment. When twins do go to term, the abortion and dystocia rates result in a fetal mortality rate of 20 percent. Freemartinism also reduces the total number of viable females.
Raising the odds
Sam's next question was, "Does ovsynch cause twins?" I was glad I had the information University of Wisconsin-Madison's Paul Fricke had shared last fall at the American Association of Bovine Practitioners annual meeting. Ovsynch does not cause twins, but the cows we put onto ovsynch are predisposed to twins. Without ovsynch, many of these cows would not become pregnant.
Double ovulation occurs when progesterone levels are low as the next follicle differentiates at Day 6. Cows that are cycling normally have a 16 percent chance of double ovulation, but 38 percent of cows that have been anovular will double ovulate when they finally have a next cycle.
One-fourth of cows between 50 and 60 days in milk are anovular. Sam protested that he gave two doses of prostaglandin to get cows to cycle.
I agreed that presynch works to synchronize cycling cows, but anovular cows only get started when they are ready or when a follicular wave is recruited by GnRH. GnRH is effective at getting 88 percent of anovular cows to ovulate, but 41 percent of them will have a double ovulation compared to only 4 percent double ovulation with cycling cows.
Sam's herd has challenges with cows becoming anovular in the summer during heat stress. He also experiences periodic transition cow issues due to limited bunk space or feed quality limitations. Considering these factors, having twins at Sam's is not usually a happy occasion.
He asked what we could do. That's right, Sam asked me what we could do. This is one of those teachable moments that dairy vets get out of bed for.
Look a little closer
I told Sam that we first can be very diligent at finding the cows with twins. Some practitioners are very skilled at palpating twins, but most find ultrasound to be a more powerful diagnostic tool. In the 15 years since portable ultrasound machines brought this technology to the rails and headlocks, we have gotten more sophisticated beyond simple pregnant and open diagnosis.
For twins, we take the time to scan both ovaries looking for two CLs indicating a double ovulation. These may be more apparent at a 60-day recheck than at the first pregnancy exam.
I told Sam not to tell me when a cow that I diagnosed with twins doesn't actually have twins . . . that situation happens half the time, and it just lowers my motivation for looking for them. It takes more arm strength to scan hundreds of ovaries each day, so I don't need discouragement for my extra efforts.
Often, dairymen ask if they should abort twin pregnancies and start over. Some practitioners have some success with embryo reduction, but commonly these attempts result in complete pregnancy loss. In those situations, we have difficulty getting the cows pregnant again. When we do, they have a higher rate of twinning on the next pregnancy 60 to 100 days later.
Our best strategy is to dry off cows diagnosed with twins two weeks early and put them right in the close-up pen if there is room. Sam agreed we could take those steps because it was all on me. He just had to remind me to take the time to look for twins and not complain when I diagnosed them.
Fewer twins are possible
Our next opportunity is to reduce twin pregnancies. We can help keep cows cycling by doing a great job of cooling and hydration. Quality feed and enough bunk space for both dry and fresh cows also keep cows cycling by reducing negative energy balance.
There are some changes we can make in our reproduction program that can help, too. Double ovsynch and G6G create fewer twins because the GnRH that initiates cyclicity is followed by another GnRH that creates the breeding follicle. We don't breed the first ovulation as that is more commonly a double ovulation.
Every dairy we have converted to these programs has seen worthwhile improvements in reproductive performance. Of course, they have to be excellent at injection compliance, and it is more work at first. In the long run, it may be the same amount of work because more cows get pregnant requiring less recycling.
After we get a large proportion of cows pregnant on first service, the next challenge is getting open cows rebred. An advancement here is a resynch program called GGPPG. GnRH is given to all bred cows on Days 25 to 31 postbreeding, and a pregnancy exam is done at Days 32 to 36. Open cows get a second GnRH to start ovsynch at open diagnosis and receive a dose of prostaglandin on Days 7 and 8.
The first dose of GnRH at Day 25 initiates cyclicity while the second one recruits the breeding follicle. Once again, we are breeding the second cycle, not the first one. The first cycle is more likely to be a double ovulation.
Sam scratched his head and said he'd have to think about those changes. I suggested we lay the protocol dates out on a calendar so he could look at them and we would discuss them more at our next herd check. In the meantime, he could think about how good his protocol compliance is.
Reproduction drives the productivity of the dairy, but twins are too much productivity for profitability. Spend some time discussing multiple birth prevention with your vet. Twins don't just happen.
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1307_444
Pregnant with twins," I announced as I scanned cow 13478. Sam dutifully entered the information in his handheld device, but the slump of his shoulders was more dramatic than if I'd called 13478 open.
Even though only half of the cows diagnosed with twins at 32 days carry them both to term, and there are several potential outcomes, only a few of them are good. One good outcome is that one of the twins would be resorbed and 13478 would have a normal single birth. Another is that twins would be carried to term, born alive, and 13478 would have no metabolic issues postpartum. Yes, that does happen, more often on some farms than others.
The bad outcomes include resorption of both embryos or abortion late enough that it isn't viable for 13478 to be rebred. It would also be bad if 13478 had significant postpartum issues leaving the herd during the first 60 days in milk. This may not pay back her dry period investment. When twins do go to term, the abortion and dystocia rates result in a fetal mortality rate of 20 percent. Freemartinism also reduces the total number of viable females.
Raising the odds
Sam's next question was, "Does ovsynch cause twins?" I was glad I had the information University of Wisconsin-Madison's Paul Fricke had shared last fall at the American Association of Bovine Practitioners annual meeting. Ovsynch does not cause twins, but the cows we put onto ovsynch are predisposed to twins. Without ovsynch, many of these cows would not become pregnant.
Double ovulation occurs when progesterone levels are low as the next follicle differentiates at Day 6. Cows that are cycling normally have a 16 percent chance of double ovulation, but 38 percent of cows that have been anovular will double ovulate when they finally have a next cycle.
One-fourth of cows between 50 and 60 days in milk are anovular. Sam protested that he gave two doses of prostaglandin to get cows to cycle.
I agreed that presynch works to synchronize cycling cows, but anovular cows only get started when they are ready or when a follicular wave is recruited by GnRH. GnRH is effective at getting 88 percent of anovular cows to ovulate, but 41 percent of them will have a double ovulation compared to only 4 percent double ovulation with cycling cows.
Sam's herd has challenges with cows becoming anovular in the summer during heat stress. He also experiences periodic transition cow issues due to limited bunk space or feed quality limitations. Considering these factors, having twins at Sam's is not usually a happy occasion.
He asked what we could do. That's right, Sam asked me what we could do. This is one of those teachable moments that dairy vets get out of bed for.
Look a little closer
I told Sam that we first can be very diligent at finding the cows with twins. Some practitioners are very skilled at palpating twins, but most find ultrasound to be a more powerful diagnostic tool. In the 15 years since portable ultrasound machines brought this technology to the rails and headlocks, we have gotten more sophisticated beyond simple pregnant and open diagnosis.
For twins, we take the time to scan both ovaries looking for two CLs indicating a double ovulation. These may be more apparent at a 60-day recheck than at the first pregnancy exam.
I told Sam not to tell me when a cow that I diagnosed with twins doesn't actually have twins . . . that situation happens half the time, and it just lowers my motivation for looking for them. It takes more arm strength to scan hundreds of ovaries each day, so I don't need discouragement for my extra efforts.
Often, dairymen ask if they should abort twin pregnancies and start over. Some practitioners have some success with embryo reduction, but commonly these attempts result in complete pregnancy loss. In those situations, we have difficulty getting the cows pregnant again. When we do, they have a higher rate of twinning on the next pregnancy 60 to 100 days later.
Our best strategy is to dry off cows diagnosed with twins two weeks early and put them right in the close-up pen if there is room. Sam agreed we could take those steps because it was all on me. He just had to remind me to take the time to look for twins and not complain when I diagnosed them.
Fewer twins are possible
Our next opportunity is to reduce twin pregnancies. We can help keep cows cycling by doing a great job of cooling and hydration. Quality feed and enough bunk space for both dry and fresh cows also keep cows cycling by reducing negative energy balance.
There are some changes we can make in our reproduction program that can help, too. Double ovsynch and G6G create fewer twins because the GnRH that initiates cyclicity is followed by another GnRH that creates the breeding follicle. We don't breed the first ovulation as that is more commonly a double ovulation.
Every dairy we have converted to these programs has seen worthwhile improvements in reproductive performance. Of course, they have to be excellent at injection compliance, and it is more work at first. In the long run, it may be the same amount of work because more cows get pregnant requiring less recycling.
After we get a large proportion of cows pregnant on first service, the next challenge is getting open cows rebred. An advancement here is a resynch program called GGPPG. GnRH is given to all bred cows on Days 25 to 31 postbreeding, and a pregnancy exam is done at Days 32 to 36. Open cows get a second GnRH to start ovsynch at open diagnosis and receive a dose of prostaglandin on Days 7 and 8.
The first dose of GnRH at Day 25 initiates cyclicity while the second one recruits the breeding follicle. Once again, we are breeding the second cycle, not the first one. The first cycle is more likely to be a double ovulation.
Sam scratched his head and said he'd have to think about those changes. I suggested we lay the protocol dates out on a calendar so he could look at them and we would discuss them more at our next herd check. In the meantime, he could think about how good his protocol compliance is.
Reproduction drives the productivity of the dairy, but twins are too much productivity for profitability. Spend some time discussing multiple birth prevention with your vet. Twins don't just happen.
1307_444
