Calf nutrition continues to evolve, and recent years have delivered exciting new insights and technologies that are shaping the future of calf rearing. That's the view of Georgina Thomas, Young Animal Feed Technical Sales Manager at Trouw Nutrition, who joined Dr Juliette Wilms, a researcher at Trouw Nutrition, to talk through where the science on calf milk replacer has progressed.
Feeding more milk
The starting point is volume. Trouw Nutrition’s market research found 65% of UK farmers were feeding six litres or less, a level that when feeding a traditional calf milk replacer, or whole milk, may struggle to cover maintenance, never mind support growth. Compare that with what a calf drinks naturally: Juliette puts it at 10 to 12 litres a day, around 20% of birth bodyweight as volume fed. Eight litres, once considered generous, is now regarded as a moderate level of nutrition. Anything below eight litres at 150 grams per litre is classed as a low feeding plane.
Both guests also pointed to Trouw Nutrition's long-running trial comparing four and eight litres of milk pre-weaning which showed the long lasting impact of milk allowance. The study found heifers on the higher plane produced 1.8kg per day more fat-and-protein-corrected milk in their second lactation and were around half as likely to be culled in the third lactation. Georgina also referenced a life cycle assessment showing following LifeStart principles can cut a dairy cow's climate change potential by around 6% in CO2 equivalents.
Bringing milk replacers closer to nature
When we are recommending increasing the feeding level, milk replacer formulation becomes more important. That's where Juliette's research has focused — specifically on fat inclusion and composition. A calf is born with limited energy reserves, at just 3% bodyweight fat, and colostrum, at approximately 40 to 45% fat on DM basis, represents a serious energy input early in life. Historically, calves have then dropped straight onto a milk replacer low in fat and higher in lactose. Pushing lactose too high can lead to osmolality levels above 450 milliosmoles per kilogram, well above the 300 to 350 mOsm/kg typical of whole milk. In young calves that can impair gut integrity and may lead to osmotic diarrhoea. Raising fat levels automatically means lactose is lowered, which aligns with bovine whole milk — Trouw Nutrition’s calf milk replacers use a blend of roughly 65% palm oil to 35% coconut oil to mimic the fatty acid profile of whole milk. However, this still results in differences between the fatty acid profile of the fat fraction of milk replacer compared to whole milk.
Juliette's work has centred on closing that gap, in particular restoring short and medium-chain fatty acids — butyric acid (C4) and caproic acid (C6) — that occur naturally in mammalian milk but have been technically very difficult to include at high levels in a milk replacer product. Trouw Nutrition has developed patent-pending technology to restore these to natural levels, with the clearest benefits showing up in the development of the rumen and intestines.
The gut lung axis is one of the more striking points from the conversation. Juliette cited data showing a calf that's had a scour episode is two and a half times more likely to develop respiratory disease — in some references, closer to three times — a connection she puts down to the shared mucosal immune system between gut and lung.
The hidden cost
The economics stack up too. Georgina put figures on it: diarrhoea affects an estimated 15 to 20% of calves across Europe, at €60 to €100 (£51 to £86) a case before mortality; respiratory disease affects 10 to 15% at €80 to €150 (£69 to £129) per case, plus €20 to €40 (£17 to £34) per pen mate — meaning one sick calf in a group of ten can cost €260 to €500 (£223 to £429) in total.
None of this comes free, and Georgina was upfront that milk replacer, especially high-skim, high-fat product, isn't cheap. Her argument is to judge it on the value it delivers rather than price per litre — factoring in the cost of pasteurising whole and additional feeding logistics and management, and setting expected performance against actual energy intake.
The takeaway from both guests was the same: get the basics right — colostrum, hygiene, ventilation, stockmanship — then use nutrition as an insurance policy on top. Calf milk replacer that's feeding for resilience, not just growth, is what closes the gap between what mother nature intended and what most calf sheds are currently delivering.