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Interview with Dr Esteban Balla, Veterinary Expert in Bovine Reproduction
In modern livestock farming, every detail matters. Knowing the true quality of semen before insemination can mean the difference between a successful pregnancy and a missed opportunity. Yet, many farms still rely on subjective and inconsistent methods. Addressing this challenge, technologies like Dynescan enable, for the first time, precise and reliable semen analysis directly on-farm, without the need for laboratories or visual diagnostics.
We interviewed Dr Esteban Balla, a leading Argentine expert in bovine reproduction, about his experience using Dynescan under real working conditions. The interview offers practical insights into how this precision tool is transforming decision-making for veterinarians, technicians, and producers in reproduction.
Contenido
Where did you train? How many years have you been practising? Where do you work?
Esteban Balla:
“I am a Veterinary Surgeon, having graduated from the Catholic University of Córdoba, Argentina. I hold two specialisations: one in Bovine Reproduction and another in Bovine Production. I have spent the past 23 years providing reproductive consultancy for both beef and dairy herds, applying a range of reproductive biotechnologies.
My work includes artificial insemination, reproductive ultrasounds, collection, freezing, and transfer of bovine embryos, as well as andrology—conducting pre-breeding evaluations of bulls and assessing the semen quality of frozen straws.
I am the founder of S.I.B.R.A. (Comprehensive Service for Biotechnologies in Animal Reproduction), a company through which I provide professional services in Argentina and other Latin American countries.”
How many semen quality analyses do you do per year?
Esteban Balla:
“Each year, I carry out around 900 semen quality analyses, including both bulls and frozen straws, depending on the type of reproductive management adopted by my clients—whether they rely exclusively on artificial insemination or use bulls in the herd.
These analyses are essential to ensure that semen quality is adequate and that the selected bulls have the capacity to successfully transfer their genetics.”
How many bulls can you evaluate in a day?
Esteban Balla:
“The number of bulls you can assess in a single day depends heavily on the facilities available at the farm. I’ve managed to evaluate up to 55 bulls in one day. Bull fertility evaluations are not a one-person job—it requires at least two professionals. While one carries out the physical inspection of the bull, the other collects the semen and performs the analysis. We don’t just assess semen quality; we also evaluate the bull’s physical and health status. Blood and preputial mucosa samples are taken to determine their sanitary and physical condition.
It also depends on the support staff available to help gather and restrain the bulls. From my experience, it takes around 10 to 15 minutes per bull. That time is enough to restrain the bull, perform a physical examination of the internal glands, testicles, penis, prepuce, limbs, mouth, and eyes, and collect blood and preputial samples to test for reproductive diseases, as well as collect semen. While the semen is being analysed in the lab we’ve set up using the Dynescan, the assistant brings in the next bull, and we carry out the physical examination during the automated analysis process.”
Before having a Dynescan, how did you evaluate semen quality? What challenges did you face?
Esteban Balla:
“We face many challenges—the first, of course, is the safety of the animal, and another is the safety of the operators, to avoid injuries and ensure we collect a good semen sample that reliably reflects what’s happening inside the bull’s testicles.
I’ve been using the Dynescan daily for almost three years now. Before that, I carried out semen quality analysis in the field, right next to the animal, using a standard optical microscope. That came with many more challenges, especially in terms of keeping the sample clean and interpreting results accurately given the variability in temperature and hygiene conditions during collection.”
Why do you typically reject a bull?
Esteban Balla:
“A bull is usually evaluated right from the moment it enters the holding pen—we observe how it walks, behaves, and interacts with other bulls. We check if it walks and runs properly, which helps us identify any physical issues that might prevent it from mounting females later on.
At some farms, we also carry out a libido test, which involves assessing the bull’s willingness to mount. We place a stationary animal or a dummy in the pen and allow the bulls to move around it, counting how many times each bull attempts to mount. Based on that number, we determine their libido level. Some bulls show no interest at all and remain indifferent—those are immediately eliminated from the process without continuing to the next steps.
The bulls that pass this initial stage go on to receive a full physical, sanitary, and reproductive examination.”
How has Dynescan helped you evaluate fresh semen?
Esteban Balla:
“Dynescan allows me to evaluate motility over time, which is crucial. What I value most about this tool is that it doesn’t just measure initial motility—it shows how motility evolves under low-oxygen conditions over time, which mimics the environment sperm cells encounter in the female reproductive tract.
In just 15 minutes, you can observe the transition from an aerobic to an anaerobic environment. The sperm that survive this transition are the ones most likely to fertilise. This allows me to identify early on which bulls produce sperm that cannot tolerate the shift to low-oxygen conditions.
Based on these results, we determine whether a bull is suitable for natural service within the herd. Across the Americas, in farms where no pre-breeding evaluation of bulls is performed, up to 50% of bulls may be culled the first time they are assessed. However, in farms where annual bull evaluations are conducted, that percentage drops significantly, to around 10–15%.”
How do you prepare samples for the Dynescan?
Esteban Balla:
“Preparing samples for testing with the Dynescan is quite straightforward. Here are the steps I follow:
Equipment setup: I set up the Dynescan and the water bath on a work table next to the cattle crush or in the back of my vehicle, connected to the car battery.
Slide preparation: I place a fixed-volume four-channel slide inside the powered-on Dynescan so the slide can reach the correct temperature.
Data entry: I enter the bull’s details into the Dyneval software. This allows me to generate a PDF report later, which I can then share with the client.
Visual inspection: After semen collection, I evaluate the sample visually to estimate its concentration. I use the parameters from the Canadian school of Dr Albert Barth, which estimates sperm concentration based on the colour and density of the ejaculate.
Short test: I take a raw, undiluted sample and load the slide using a micropipette, then insert it into the Dynescan. I run three analyses at one-minute intervals over a total of three minutes. If the Progressive Motility Percentage is below 50%, I take another sample from the collection tube and apply a dilution.
Dilution and long test: If the three-minute test result is not satisfactory, I dilute the sample—usually at a 1:9 ratio (1/10 dilution factor)—to bring it within the appropriate range for sustained motility analysis. Then I run a 15-minute test (five analyses, each spaced three minutes apart).
Result evaluation: At the end of the test, I obtain a graph showing how semen motility behaves dynamically over time. If motility drops sharply after the first few minutes, it indicates the semen quality is compromised.
Repeat testing: If I have any doubts about the sample quality, I can repeat the semen collection to ensure the results are reliable.”
Preparing the sample takes just a couple of minutes, which allows for fast and accurate results to assess semen quality right there in the field.”
What are the advantages of using a Dynescan?
Esteban Balla:
“Portability is a decisive factor when it comes to evaluating right next to the animal. I also find it advantageous that the Dynescan can analyse samples with a very wide concentration range. That’s a great advantage in the field because handling a diluent with the necessary cleanliness conditions to use it with semen is very cumbersome. The number of samples I dilute has decreased by 60%. Reducing steps is critical to minimise potential risks of damaging semen quality.
If, by visual observation, I determine that the sample has more than 550 million sperm cells per millilitre, I need to dilute it, but it doesn’t have to be very precise, because the concentration range in which the Dynescan analyses the sample with the lowest standard error is between 1 million and 550 million sperm cells per millilitre. So, if I have a sample with 800 million sperm cells, I make a 1-to-1 dilution, bringing the sample down to 400 million sperm cells.
If dilution isn’t necessary, I take a sample from the tube using a micropipette, load the slide, and place it inside the Dynescan for analysis.
Another advantage of the Dynescan for maintaining the sample quality over time is that inside, there is a thermal stage that keeps the sample at 37.5 degrees for as long as necessary. This way, samples are not affected by external heat or cold. Moreover, the way it is built protects the sample from the surroundings. Even if there’s a lot of wind or dust, it’s not a problem, because dust doesn’t interfere with the results.”
What criteria do you use to approve or reject a bull?
Esteban Balla:
“One of the criteria I use to approve a bull is that progressive motility is greater than 50% and sustained over time. Another important criterion is the percentage of normal cells. I’m not only interested in the initial percentage, but also in whether it remains stable under anaerobic conditions. If the semen is capable of maintaining good motility, it means it has a greater potential to fertilise.”
When would you re-evaluate a bull?
Esteban Balla:
“I re-evaluate a bull if its results are inconsistent or if the conditions under which it was evaluated are not optimal. In that case, I would take a new sample after an appropriate interval to ensure the results are reliable.”
Has the data from Dynescan ever motivated you to examine a bull more closely? Can you describe a situation and what you did afterwards?
Esteban Balla:
“Yes, several times. For example, one bull showed acceptable initial motility, but there was a sharp drop just a few minutes later. Based on that evidence, I decided to examine him more closely and discovered he had an interdigital pain that wasn’t showing clinical signs, but his spermatogenesis was already affected. After appropriate treatment and a recovery period (at least 60 days), his results improved significantly.”
What do your producers think about bull fertility testing with a Dynescan?
Esteban Balla:
“Throughout Latin America, and specifically in Argentina, there are generally two types of producers: those who run their production systems in a traditional way, and those who are constantly looking to incorporate new biotechnologies and improve their output. With the first group, it’s a bit more challenging to introduce biotechnologies, but as soon as they see the results from the Dynescan, they don’t hesitate to adopt it.
Producers who are at the forefront have no hesitation in adopting new biotechnologies. As a technical advisor in reproduction, incorporating new biotechnologies allows me to provide a more professional and objective service, helping each producer achieve the best possible results and make their production more efficient.”
Do you notice improvements in conception rates?
Esteban Balla:
“Yes, improvements in reproductive parameters are noticeable, but it’s important to keep in mind that semen is just one of the factors that affect the results. Early identification of bulls with fertility problems within the herd allows me to use only the most fertile ones.”
In what other ways does Dynescan help you in your work?
Esteban Balla:
Have you used it before for In Vivo or In Vitro embryo transfer?
Esteban Balla:
“Yes, and it has been fundamental. By performing the analysis with Dynescan prior to embryo production, we can ensure that the semen used is of the highest possible quality, thereby increasing the chances of success.”
If someone is interested in Dynescan, what would you say to them?
Esteban Balla:
“I’d be happy to share my experience. I’d be delighted to arrange a video call or even chat via WhatsApp—whichever is more convenient. Over the coming months, I’ll be working with the Dynescan in Buenos Aires, Montevideo, Bogotá, São Paulo, and possibly in the Dominican Republic. If you’re near any of those cities—or in Córdoba—I’d be glad to schedule a meeting as part of my itinerary. Simply leave your contact request through Dyneval, and I’ll be in touch.”
Dr Esteban Balla (DVM)
Bovine Reproduction & Production Specialist,
SIBRA Argentina
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