High quality milk powder unlocks better lifetime performance

Who is this for?

This technical update is essential reading for anyone involved in dairy heifer rearing and herd replacement decisions.

• Dairy farmers

• Calf rearers

• Farm managers

• Nutritionists

• Veterinarians

• Agricultural advisors

What this research covers

In this technical update, Dr Jessica Cooke reviews the findings of a long-term study conducted at AFBI Hillsborough in Northern Ireland. The study tracked 80 Holstein Friesian dairy heifers from birth through to their third calving, with calves fed four different milk protein-based diets as pre-weaned calves in 2018-19. 

Dr Cooke explains how the research compared high quality skim milk powder, concentrated whey protein (CWP), including products such as Imunopro®, and lower quality simple whey powder (WP) formulations. While well-formulated milk replacers using either high-quality skim or concentrated whey protein delivered comparable calf performance, significant differences emerged when comparing concentrated whey protein against simple whey powder in later life. 

The financial impact

AHDB figures suggest each day's delay beyond 24 months age at first calving costs £2.87 per heifer. The 22-day difference between CWP-fed and WP-fed heifers translates to measurable savings for dairy businesses.

Frequently asked questions

Does calf milk replacer really affect lifetime performance?

Yes. This long-term study demonstrates that what calves are fed pre-weaning makes a measurable difference when they join the milking herd. Heifers fed high-quality concentrated whey protein showed better fertility outcomes and reached first calving earlier than those fed lower quality whey powder formulations. 

Is skim-based or whey-based milk replacer better for calves? 

When properly formulated and processed, both high-quality skim-based (with >40% skim content) and concentrated whey protein-based milk replacers deliver comparable calf performance. The key is quality and processing, not simply the protein source. Poorly processed milk-derived protein (be it skim or whey) can reduce digestibility and increase the risk of health issues. 

What's the difference between whey powder and concentrated whey protein? 

Concentrated whey protein typically contains around 35% protein, while standard whey powder contains only 12.5-13% protein. Liquid whey from cheese production can be processed into whey powder, delactosed whey or concentrated whey protein, each with different protein and lactose content. This means whey powder in a finished milk formula will not contribute the same level of dairy protein as concentrated whey protein. 

Why does processing temperature matter for whey protein? 

The whey fraction of milk contains valuable bioactive proteins including immunoglobulins and lactoferrin that support calf health and growth. High processing temperatures denature these proteins and reduce their effectiveness. Research shows that at 85°C, over 60% of whey proteins were denatured within 30 minutes, while at 65°C only 15% were affected. Low-temperature ultrafiltration helps preserve these beneficial proteins. 

How can I identify a high-quality milk replacer? 

Check how ingredients are listed on the label, as they must appear in order of inclusion level. Confirm your high-quality protein source is listed first. Ask your feed rep or manufacturer to explain the label, particularly how whey protein is described. For skim-based products, look for >40% skim content. Don't be afraid to ask about raw material origins and manufacturing methods. 

What is the target age at first calving? 

The target is 24 months at first calving, with heifers achieving 85-90% of mature body weight. Reaching this target supports better fertility, improved survival, higher milk production, better udder health and increased rate of genetic gain. It also reduces the non-productive period and lowers the environmental footprint per litre of milk produced.