If you have had children in the last 10 years, you’re probably familiar with fetal ultrasound images. The black-and-white “pictures” of the developing fetus let doctors diagnose health problems and, often times, allow parents to know the sex of their child prior to birth.
What has become routine in hospitals also can become part of your dairy’s reproductive management program. As ultrasound technology has improved, and the cost has declined, on-farm use has become more practical and cost-effective. Using ultrasound on your farm — either by a veterinarian or by training yourself or an employee — allows you to detect pregnancy as early as 25 days, find cows carrying twins, identify types of cysts, and determine fetal sex.
Adds a visual dimension
Having veterinarians diagnose pregnancy and reproductive-related problems by rectal palpation has been a key part of reproductive management for decades. However, because ultrasound provides a visual image of follicles and fetuses, veterinarians and producers can examine cows earlier and “see” more information. (To learn more about the technology behind ultrasound, see the related article, “How ultrasound works,” on page 39.) According to Paul Fricke, assistant professor and extension specialist in dairy reproduction at the University of Wisconsin, ultrasound has great potential to improve the reproductive efficiency on dairy operations. Here’s why:
- Detects pregnancies earlier. By using ultrasound, pregnancy can be determined between 25 to 31 days post-breeding, while rectal palpation is not recommended until approximately 40 to 42 days after breeding. Dairy producers who are interested in lowering days open can take advantage of this by immediately re-enrolling open cows in the dairy’s breeding program.
This early pregnancy checking also can help measure early embryonic deaths, says Bill Wailes, an extension dairy specialist at Colorado State University and partner in a 2,000-cow dairy in Hudson, Colo., that uses ultrasound. The difference in embryo quality is easily detected with ultrasound, he says. “You can look at two embryos in two cows, both 28 days after breeding, and see differences in embryo quality.” For example, one may have a stronger heartbeat which indicates it is a more viable embryo.
Many diseases, such as bovine viral diarrhea, can cause cows to abort fetuses between 21 and 40 days after breeding. This is usually just long enough for a cow to miss a heat, but not long enough for the pregnancy to be caught by rectal palpation. Fricke estimates 14 percent to 16 percent of pregnancies diagnosed at 28 days will result in early embryonic death (EED). By tracking EED, you can get a head start on eliminating diseases that silently steal profits from your farm.
Kipp Sanders, with E.I. Medical, a Loveland, Colo., a manufacturer of ultrasound equipment, also finds that ultrasound provides producers with a sense of certainty about pregnancy diagnosis. In the past, when cows were palpated and diagnosed pregnant, but later found open, veterinarians and producers could only speculate about the problem. Perhaps a misdiagnosis occurred, or the palpation caused the pregnancy loss or a disease caused the death of the embryo. With ultrasound, more certainty in diagnosis is possible — with producers seeing the results for themselves.
- Identifies twins. Another benefit of using ultrasound is identifying cows carrying twins. The twinning rate in the U.S. continues to rise, and research shows that twins reduce profitability and reproductive efficiency in dairy cows.
Twins reduce profitability due to lower heifer replacement rates. The heifer replacement rate in single births ranges from 42 percent to 48 percent, compared to 29 percent and 42 percent in twin births, according to Fricke. Producers often think that freemartins (a sterile female born with a male twin) lower the replacement rate, but twin mortality is the real culprit — 17 percent in twins, compared to just 3.2 percent in single births.
Research also suggests that higher-producing cows have more twins (see related article, “Double trouble” on page 40). Twinning often reduces production in these cows, and also increases their chance of dystocia and other fresh-cow problems.
This was true at Oakwood Dairy, a 1,200-cow operation in Auburn, N.Y. The herd had a twinning rate of 6.1 percent in 1998, and found that approximately 50 percent of the cows which had twins were culled in that lactation for reproductive failure, metabolic problems and low production. Now, the dairy’s veterinarian, Tom Gill, conducts pregnancy checks with ultrasound to identify cows with twins. Those animals are dried-off three to four weeks early to minimize problems at calving and subsequent problems in the next lactation.
- Evaluates follicular structures. Using ultrasound in cows during the first 30 to 60 days after calving can provide benefits also, says Wes Jacobs, a veterinarian in Turlock, Calif., who provides ultrasound training as a part of his consulting practice. “You can identify everything on the ovary with ultrasound,” he says.
Some veterinarians suggest treatments for cysts based on the type — follicular or luteal — while others prescribe the OvSynch protocol for both types. If your treatment protocol is type-based, ultrasound can detect the type more accurately than rectal palpation. A University of Missouri study found that veterinarians correctly identified cyst type 85.1 percent of the time with ultrasound, compared to 51.1 percent accuracy with rectal palpation. “Once you know what type of cyst you have, you can take the appropriate management steps,” says Sanders.
- Improves reproductive management. Having your own on-farm equipment gives you more flexibility, timing-wise, than having to rely on a veterinarian’s schedule. Small groups of cows can be detained for short periods of time, which can mean less hassle for you and your employees and greater cow comfort. Additionally, involving your employees will keep them more focused on the importance of reproductive management.
- Determines sex of fetuses. Ultrasound allows a skilled operator to determine the sex of the fetus at about 44 to 60 days post-breeding. For some producers who market cattle, the ability to determine the sex of the fetus offers financial benefits. Additionally, the sex of the fetus may be useful when determining whether to cull an animal.
Offset the cost
Many veterinarians and producers have been slow to adapt ultrasound due to its price. Typically, the equipment will cost around $7,000 to $8,000, says Jacobs. If you or an employee has to be trained on the equipment, the total cost can increase to about $10,000.
For large dairies that purchase ultrasound equipment and train a manager or employee to preg-check the herd, ultrasound pays for itself within one to two years, says Jacobs. For example, if the veterinarian charges $100 per hour for palpation, and it takes two hours each week, the dairy is spending at least $800 per month, or $9,600 per year. That, alone, would pay for the ultrasound device in one year.
And, you also need to consider the payback that you receive from improved reproductive management.
Paul Colgan, herd manager and part owner at Oakwood Dairy, is hopeful that the ultrasound program will detect more sets of twins. Studies suggest that each set of twins on the dairy can cost between $100 to $250. For Colgan’s dairy, which had 55 sets of twins in 1998, that would have meant losses of between $5,500 and $13,750. Paying his veterinarian an additional $25 per hour for ultrasound diagnosis will allow the dairy to manage the problem better — and hopefully cut some of that loss. And, Colgan has already seen a decrease in the number of days open, as a result of checking cows at 30 days after breeding.
As you start the new year, consider a new technology to move your reproductive program into the 21st century.
How ultrasound works
“Ultrasound is like putting eyes on the tips of your finger,” says Kipp Sanders, sales manager of speciality products for E.I. Medical, of Loveland, Colo. It allows the user to see something that previously was only evaluated by feel.
Ultrasound technology uses sound waves undetectable by the human ear to generate images of body tissues. A device called a transducer is put in the rectal tract of the cow and placed over the reproductive organs. Through a crystal in the transducer, sound waves are transmitted to, and received from, these body tissues.
Fluids in the body absorb the sound completely and do not return the signal, resulting in black images on the ultrasound screen. Conversely, thick and dense structures, such as the cervix, will reflect the sound wave and appear white. Most body tissues will appear in shades of gray, depending on their density.
For example, when you look at the uterus of a pregnant animal, you see a black area due to the presence of amniotic fluids. Within the black area, the calf embryo will appear as a white area due to fetal tissues.