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- Insect oil provides viable energy source in calf milks
Insect oil provides viable energy source in calf milks
With Bianca Theeruth, Ruminant Technology Application Specialist
An energy source, derived from high quality fats, is essential in calf milk replacers. It provides more than twice the energy of protein or carbohydrate and is essential for growth, development and health in young calves, particularly in the first few weeks of life
“The best fat sources are those that closely mimic maternal milk, which has a mix of short, medium and long chain fatty acids,” said Cargill’s youngstock specialist Bianca Theeruth.
“Alternative fats must be digestible, provide enough energy for the uptake of micronutrients such as vitamins, and support gut health – just like mother’s milk.”
In her conference presentation in July this year, Ms Theeruth explained that pre-BSE, pig lard and beef tallow were used as fat sources in calf milks due to their close match to the ‘natural’ milk. “And in general, these provided a better match to the fatty acids in maternal milk than plant fat sources.
“But BSE put an end to their use in calf milk replacers,” she added, noting that this was an industry decision for consumer perception reasons. “Although pig lard could still be used in calf milk replacers, animal fats in general were out of favour in the post-BSE-era.”
Since the mid-90s, and for almost three decades, refined vegetable oils have been the dominant fat source in most European calf milk replacers. A combination of palm, coconut and soya oils are used to best mimic milk fat and provide the best possible balance of fatty acid chains to promote digestibility. Palm oil provides long chain fatty acids and coconut oil is rich in medium chain fatty acids.
“Rapeseed is also being included in calf milk replacers. This plant oil is rich in omega 3 and 6 and brings immune system benefits,” she added. “However, it is high in polyunsaturated fat so an antioxidant has to be included in the replacer too.”
New Options
Now, with more understood about BSE and some re-assessment of the rules, there’s a growing interest in the re-introduction of animal fats in livestock diets.
And alternative fat and energy sources might also help to overcome an issue associated with the sustainability of some plant-derived ingredients, particularly tropical oils.
Cargill has investigated the options in today’s climate, where performance alongside environmental and economical sustainability are important criteria. Its work has included the use of insect oil, with black soldier fly larvae oil proving to be a strong contender as an energy source.
“This oil is rich in medium chain fatty acids, including lauric acid,” adds Ms Theeruth. “These fatty acids are quickly absorbed - which is ideal for young calves which have limited digestive enzyme activity, and it has antimicrobial properties that support gut health.”
And compared with many other animal and plant-derived fat sources, insect oil offers a more sustainable energy source with a low carbon footprint compared with many alternatives.
“Insect oil has a similar medium chain fatty acid profile to coconut oil, but it can be more sustainable. Efficient insect oil production supports waste upcycling as in these systems insects are reared on organic waste or byproducts, which supports a circular economy.
“Fat - in the form of oil - and protein derivatives of the black soldier fly have been used successfully in pig and poultry diets for some time,” she said.
Trail Success
On farm trials have demonstrated that insect oil in calf milk replacers can perform on par with traditional fat sources.
Results from a Cargill trial, published in the Journal of Diary Science 2025, showed that black soldier fly (BSFL) oil can replace some of the vegetable oil in calf milk replacers with favourable results.
The trial, carried out in on a commercial farm in Italy involving 100 Holstein calves with an average birth weight of 37.2kg, evaluated the effect on performance of feeding calf milk replacers with varying ratios of tropical
Key Facts
- Some animal fat sources, including insect oil, can now be used in calf milk replacers
- Insect oil is an excellent source of energy to support growth and a valuable source of medium fatty acids. It has high levels, typically more than 40% - of lauric acid. Lauric acid is known for its ability to inhibit the growth of certain pathogenic bacteria in vitro and support the immune system
- Trials have shown that black soldier fly larvae oil can be used in place of tropical plant-based oils with no impact on performance and the possibility to support livestock wellbeing. It may also exhibit a positive effect on gut health and faecal quality through its ability to modulate intestinal microbiota
- Black soldier fly larvae oil helps support sustainability in calf production systems.