Why milk fat composition in calf milk replacer matters

Optimising fat composition in calf milk replacer to focus on short-chain fatty acids could unlock better growth, stronger gut health and enhanced disease resilience, according to new research.

Speaking at CowManagement’s National Youngstock Conference in Birmingham, Trouw Nutrition’s Georgina Thomas said that conventional milk replacers rely heavily on vegetable oils (typically palm and coconut).

These offer energy but lack structural complexity, especially short-chain fatty acids (SCFAs).

This can compromise both energy provision and gut health.

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SCFAs, such as butyric and caproic acids, are naturally abundant in cow’s milk and play a key role in the calf’s gut development and function.

However, their inclusion in calf milk replacers has been limited by their strong odour and poor palatability.

Georgina Thomas © Charlotte Cunningham

Digestible energy source

Trouw Nutrition has pioneered an encapsulation process that allows these short-chain fatty acids to be included in a spray-dried, stable form in milk replacer, to deliver energy in a structure that young calves can digest.

Ad-lib milk feeding trials, over 12 weeks, used two groups of pre-weaned calves on identical volumes of milk replacer, but the treatment group’s formulation was enhanced with encapsulated short-chain fatty acids.

Georgina says key outcomes included:

• Increased starter intake Calves receiving encapsulated SCFAs consumed 26% more solid feed pre-weaning, demonstrating better rumen development and a smoother transition at weaning. Individual intakes reached up to 3-4kg/day by week 12
• Higher growth rates The SCFA group achieved an average of 15kg more liveweight gain over the 12-week period compared with the control group
• Improved gut development At week five there were significantly taller villi and an 8-10% heavier small intestine in SCFA-fed calves – evidence of increased absorptive surface area and digestive function
• Enhanced rumen development Rumen papillae were markedly more developed in the SCFA group (before concentrates had been introduced), supporting the link between milk-phase nutrition and future rumen functionality.

Georgia says calves with the improved fatty acid profile are developing rumens better prepared for dry feed uptake, which translates directly into better performance post-weaning.

Calf health gains

The study’s most striking findings, however, came from health metrics. Across the 12-week period:

• 66% fewer calves in the SCFA group required treatment for gastrointestinal issues
• There was a 60% reduction in fever cases
• Incidence of respiratory disease fell by more than 75%
• Antibiotic treatments were halved in the SCFA group over the trial period.

These results should be interpreted with caution, as a sample size of 24 calves per treatment is relatively small for assessing the impact of a dietary intervention on disease incidence and severity.

However, Georgina says there is a growing body of evidence linking gut integrity with systemic immune function and how those SCFAs were providing a clear base to support and develop the gastrointestinal tract.

“The gastrointestinal tract is the main barrier between the gut rumen and the bloodstream,” she said.

“If we can improve integrity, we can have a big impact on health status. It’s not going to change everything, but it really makes those calves more robust and resilient.”