Belgium dairy farmer raises the bar in calf rearing
“Diarrhoea in calves is not only frustrating, but also time-consuming and has a serious impact on their health and growth,” says Belgian dairy farmer Sanne Theuwissen. But since switching to a new calf milk formula, she has seen a dramatic drop in the number of cases.
From day one, a dairy calf’s development is profoundly influenced by the nutrition it receives. Providing a well-balanced diet early on is essential to set the foundation for healthy growth, resilience, longevity, and future productivity. Rearing calves is a skill that requires time, attention, and thoughtful decision-making to ensure the best outcomes – not just for the calf, but for the lactations that follow.
A great example of this approach is Sanne Theuwissen. This 35-year dairy farmer is redefining what it means to rear healthy, high-performing dairy calves. Alongside her father, she runs a farm in Bocholt, Belgium, with 279 milking cows and 277 youngstock, fed on a homegrown maize and grass ration. Sanne’s father also operates crop farming on the side, including potatoes and peas. The farm has 4 milking robots and the average production per cow is currently 12,600 litres per year, with fat at 4.15% and protein at 3.55%.
Efficiency and laser focus on calves
The strong numbers in milk production and milk solids reflect the high quality of care on all levels, but also the efficiency and laser focus that Sanne and her dad have. She explains: “Belgium has strict environmental regulations, so expansion is not an option. We also don’t want to hire extra staff, so our focus is on optimising what we already have and manage this on our own. That means every animal counts, and calf rearing must be flawless.”
Sanne’s calves receive 9 litres of milk a day, divided into 2 feedings. By using the MilkTaxi, each pen number is automatically detected, and she can select the right amount of feed for the calf and hence fill the bucket. The weight fed is registered and stored for each pen.
For years, Sanne and her father have been loyal customers of Trouw Nutrition, and the high plane of nutrition is based on the LifeStart approach from the company, showing that above 8 litres per day in 2 feedings has significant benefits for growth, development and lifetime performance.
Sanne explains that in Belgium and Luxembourg, feeding above 8 litres per day per calf is generally standard. “Other countries are more conservative, still feeding closer to 6 litres. But we believe in our approach, and we see the benefits of feeding elevated planes of calf milk replacer per calf per day.”
Calf diarrhoea: A constant menace
Despite excellent growth rates in the calves and strong milk production, calf diarrhoea remains an ever-present challenge for dairy farmers, including on Sanne’s farm. “Calf diarrhoea is indeed a constant struggle,” she says. “For years, nearly every calf on our farm had some degree of diarrhoea, usually between day 7 and day 10. It was incredibly frustrating because I followed all the protocols, did everything by the book. We even brought in the University of Ghent to take a deep dive and investigate potential pathogens. But the problem just wouldn’t go away.”
Perhaps it was the bluetongue virus that swept through the farm in 2024, which may have affected the cows, their calves, and colostrum quality. But in the end, no single cause or pathogen could be pinpointed as the reason behind the recurring cases of diarrhoea. That all began to change in May 2024, when Trouw Nutrition invited Sanne to be one of the first farmers to try their newly-launched calf milk replacer (Sprayfo Ultimo). She agreed, and that decision proved transformative. What was once a source of ongoing frustration quickly gave way to peace of mind.
Switching to a new calf milk formula
Now, after a year of using the new calf milk (in both the bull and heifer calves), maybe 1 out of 10 calves show symptoms of diarrhoea, and even then, they recover quickly. Sanne explains: “They grow faster, and they seem to be more resilient and energetic. When I walk alongside the calves and see all those healthy, shining animals I know we are doing something right. Also, other health issues in youngstock, such as respiratory problems, have been reduced. This is a combination of the different calf milk and the introduction of individual feeding, minimising risk of pathogen spreading.”
But what is the secret of this new calf milk replacer? The new calf milk Sanne is using is formulated with a specific fatty acid balance (see box) that mimics cow’s milk more closely than anything else on the market. This way, calf milk is the next best thing to cow’s milk and can naturally signal healthy calf development right from the start. This is key to better meet the biological needs of the calves and promote better gastrointestinal and rumen development, for example. The latter is key to better prepare the calf to consume and utilise solid feed and forage after weaning.
The right choice at the right time
“A sick calf costs both time and money – resources you cannot recover,” Sanne explains. “Diarrhoea, in particular, is incredibly labour-intensive. The calf stops drinking, so you must give oral electrolyte solutions, and thoroughly clean the buckets. All these activities add up and takes the joy out of the work.”
Now that diarrhoea rates have dropped significantly, Sanne has more time to focus on other tasks around the farm, including further optimising calf rearing practices.” As a farmer, you are always striving to do better; always seeing opportunities for improvement,” she says. “We are now about to inseminate the first group of heifers raised entirely on the new calf milk, and I am genuinely excited to see how they perform in their first lactation and the long-term impact on their offspring.”
What began as a trial period with the new calf milk quickly proved to be the right choice at the right time. “We are definitely sticking with Sprayfo Ultimo,” Sanne concludes.
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