Producer question: How will I be able to use ultrasound to improve my hogs?
Safranski’s answer: Ultrasound sends out high-frequency pulses and measures how the pulses bounce back. The pork industry has used A-Mode ultrasound for more than 35 years to measure backfat depth and for pregnancy detection.
A-Mode ultrasound uses a single transducer to measure the signal’s return. This offers a one-dimensional measure and is reasonably accurate for fat depth and pregnancy diagnosis.
As technology develops, tools grow more accurate and efficient. B-Mode, or real-time ultrasound, uses multiple transducers, each receiving multiple signals per second. Signals bouncing off solid bone yield a white image. Those aimed at fluid do not bounce back and yield a black image. Those bouncing off tissues produce shades of gray. This results in a two-dimensional image shown in 16 shades of gray.
Real-time ultrasound aids genetic improvement in nucleus herds as well as gilt selection in commercial herds with internal gilt multiplication. It is replacing A-Mode ultrasound in reproductive management situations, particularly for pregnancy diagnosis.
This can offer you two advantages:
- Since it presents a two-dimensional image rather than a “yes” or “no,” a trained technician won’t get false positives by pointing it at the bladder or cysts.
- Real-time ultrasound can rapidly and accurately detect pregnancy by day 24 instead of 28 to 35 days into gestation, as was the case with A-Mode machines.
There are two disadvantages to real-time ultrasound pregnancy detection. Even new, less expensive models can cost $6,000 to $20,000. Also, you need more technical expertise to use them.
As we’ve moved sows indoors, overhead costs and the cost of nonproductive-sow days has risen. Identifying open sows improves reproductive efficiency in three key ways. We reduce nonproductive days because:
1. Knowing the sow isn’t bred, we do a better job of estrous detection during the 38- to 45-day check.
2. We identify unbred sows and make decisions to cull them before they enter the farrowing house.
3. Workers doing the 18- to 24-day heat check are embarrassed if sows they note as pregnant are shown via ultrasound to be open a week or two later. I can’t overemphasize the importance of estrous detection as a factor contributing to reproductive efficiency.
What size operation can justify the cost of ultrasound? That depends on the value of time. A producer with time to do thorough breeding and estrous detection may find no value in a pregnancy check. But on most farms estrous detection isn’t perfect.
Producers with 1,000 or more sows often feel the cost of a real-time ultrasound machine is easily recovered. If your operation is too small to buy the machine, consider pooling resources with other producers or hiring a certified technician.
New ultrasound uses will spread costs out further, increasing its use.
Producers are rapidly adopting artificial insemination, largely to use boars more efficiently. While I can’t discuss AI in depth here, using two or three doses of semen per sow isn’t optimally efficient. You use multiple doses simply because insemination times are based on heat detection, which is our estimate of onset of heat. That’s then used to predict time of ovulation.
Because you don’t know the exact time any of these events occur, you give multiple semen doses at 12- or 24-hour intervals to assure adequate numbers of viable sperm in the oviduct at the proper time for fertilization.
Real-time ultrasound can provide images of the ovary and follicles from which eggs will ovulate. A sow with no follicular growth post-weaning won’t ovulate. Either cull her or treat her with a compound such as PG-600 to induce ovarian activity.
With ultrasound, you could make frequent observations of the ovary, track follicular growth and perform a single insemination. I recognize savings in semen costs today won’t make up for the time you would have to spend tracking follicular growth.
Preliminary data from the University of Missouri suggests one appropriately timed measure of ovarian follicular development could pinpoint insemination time. Researchers made transrectal observations of the ovaries daily from seven days before weaning until seven days after weaning or estrus. At each observation they counted follicles by size: small (2 to 3 millimeters), medium (4 to 5 millimeters) or large (6 to 8 millimeters).
They conducted daily estrous detections and analyzed whether follicular data could predict ovulation timing. Preliminary results were encouraging: One measure on day three post-weaning may do the trick. Subsequent studies leave open the question of whether we can perform one measure and predict ovulation accurately enough to use a single insemination. Data being collected should give more answers.
Still, the measurement can predict most of the sows that will not ovulate within one week post-weaning.
Improving meat quality is another area where ultrasound may play a role. Selecting which breeding animals will improve meat quality has been a challenge because there are no accurate live animal measures. Even with data, meat quality traits are not very heritable, with the exception of intramuscular fat or marbling.
But recent data from Iowa State University shows real-time data may be at least moderately useful in predicting marbling in live animals.
The obvious benefits of using this in genetic improvement programs should not be overlooked. And as packers develop line-speed measures of meat quality and pay for hogs accordingly, it may prove worthwhile to scan market hogs, sort and send them to different packers depending on predicted quality differences.
Tim Safranski is a swine breeding specialist at the University of Missouri, Columbia, Mo.