Heifer calves reared on a concentrated whey protein-based milk replacer diet are younger at first calving and more fertile than those receiving lower-quality milk protein in early life – a potential financial benefit worth more than £63 per heifer.

Those were the findings of a study based on dairy heifers at AFBI Hillsborough in Northern Ireland fed different milk protein-based diets as pre-weaned calves that have been monitored up until their third calving.

According to Dr Jessica Cooke of Volac milk replacers, the experimental study involved 80 Holstein Friesian calves fed four different milk replacers from birth until 56 days of age.

Dr Jessica Cooke Volac R and D managerDr Jessica Cooke Volac R and D manager

The trial highlighted that well-formulated, high-quality milk replacers with either skim milk powder (at above a 40% inclusion level), or concentrated whey protein as the major source of dairy protein, both deliver comparable animal performance.

“This work clearly showed that the presence of skim – and therefore the clotting effect of casein – is not the fundamental element within a calf milk formula influencing optimum calf growth.

“If the important milk components are processed correctly, both skim and whey proteins will be highly digestible by the high milk-fed, pre-weaned calf and will deliver good performance. The trial clearly demonstrated that there was no significant difference in calf growth or health between the different milk replacer formulations.”

Importantly, however, Dr Cooke stressed that good nutrition and calf performance is linked to more than just the type of dairy protein included in the finished milk formula.

“Important differences in amino acid and fatty acid profiles, amount of lactose, vitamins, minerals and trace elements, processing conditions and overall digestibility all contribute to calf performance,” she said.

What’s more, the data has confirmed that high-quality, pre-weaned calf nutrition favourably influences better lifetime productivity.

“What calves are fed pre-weaning certainly makes a difference as these heifers join the milking herd,” Dr Cooke said.

“Although high-quality, skim-based milk replacer-fed calves and those fed a high-quality, concentrated whey protein-based (CWP) pre-weaning diet will perform similarly in later life, some performance differences start to emerge when you compare calves fed concentrated whey protein such as Volac Milk Replacer Imunopro with those fed a lower-quality, simple whey powder-based (WP) milk replacer (see table 1).

“Not only were the CWP-fed calves five days younger than their counterparts at first breeding, but there were also some fertility differences. For example, the CWP-fed group only required 1.4 services per heifer, while the WP-fed group required two services per heifer. First service conception rate was better too in the CWP-fed group (60%) versus 50% in the WP-fed group.”

However, Dr Cooke added that a particularly important performance difference starts to emerge when you compare the AFC data.

On average, the CWP-fed calves calved first at 729 days of age, whereas the WP-fed animals calved down at 751 days – 22 days later. What’s more, 80% of the CWP-fed heifers had calved down by 24 months of age, as opposed to only 33% of the WP-fed heifers. With AHDB figures suggesting each day delay beyond 24 months AFC costs you £2.87, this performance difference alone is worth £63.14 per heifer.

Or, to put it another way, a £3157 cost to the dairy farm business every year for a 200-cow herd with a 25% annual replacement rate.”

Dr Cooke added that high-quality early life nutrition pays dividends and encouraged all calf rearers to be far more discerning over calf milk replacer choice for rearing their milking herd replacements.

“The key is to evaluate value for money carefully when purchasing a calf milk replacer. Look for a proven track record of performance. Recognise, too, that a precision-formulated product based on concentrated whey protein will provide everything the high milk fed calf needs in early life.”