Early calf growth pays dividends for years to come

The calves being reared this spring won’t enter the milking herd for another two years, but their future production may already be taking shape. New Zealand research has found growth achieved before weaning can influence milk production, longevity and performance well into adulthood.

A seven-year Bioeconomy Science Institute study led by Dr Ajmal Khan followed 324 New Zealand Kiwi-cross heifers from birth through to their fourth lactation to better understand the relationship between early growth and lifetime performance.
 

A lasting impact

The researchers found calves that grew faster before weaning stayed heavier through to calving and produced more milk and milk fat across their first four lactations.

One finding stood out: For every additional 100g per day in pre-weaning average daily growth, heifers produced around 279 litres more milk per lactation. That’s roughly 23.5kg more milk solids, a significant boost from just a small increase in early growth.

The study also found those animals were more likely to remain in the herd for longer. While every farm system is different, the findings reinforce something many farmers already know ‒ growth achieved early in life matters. The challenge is ensuring calves maintain that growth and don’t experience setbacks that can affect their future performance. 

As Khan puts it: “Feeding calves well during their first three months should be viewed as an investment, not a cost. How a calf is fed and managed in the first few months of life can influence her productivity for years to come.”
 

Protecting growth through the first three months

Good early growth comes from getting the fundamentals right. During the milk-feeding period, calves need sufficient milk or milk replacer alongside unrestricted access to clean water, high-quality calf meal and fresh pasture as their rumen develops. 

While calves often recover well from issues such as scours or pneumonia, the effects of those setbacks can linger if growth isn’t regained. Likewise, periods where calves fail to consume enough energy or quality feed, particularly around the transition through weaning can slow growth at a time when they are building the foundations for future productivity. 

The goal isn’t simply getting calves through to weaning. It’s ensuring they continue to grow steadily throughout the transition and into the next stage of their lives.
 

Don’t assume healthy means growing

Once calves are settled into the grazing rotation, they often require less day-today attention, which is also when they can be easier to overlook as the focus shifts to the rest of spring’s workload.

The best calves usually don’t need much help, and the smallest are easy to spot. Often, It’s the calves in the middle of the mob that tell the real story. Look for calves quietly drifting away from the average. They can be the first sign that feed quality, competition or another pressure is starting to have an impact.

Khan notes that if pasture quality declines after weaning, continued supplementation may be worth considering rather than expecting calves to simply grow through it. 

A calf can look healthy while still falling behind. Regular weighing helps identify those animals before a small setback becomes a bigger issue. 

DairyNZ recommends in general, target liveweights should set by: 

• at 3 months 20% 
• at 11–12 months 50% 
• at 14–15 months 60% 
• at 22 months 90% of mature liveweight¹
   

Looking ahead

The Co-op’s Net Zero Pilot Dairy Farm is currently investigating how different calf-feeding systems influence growth, labour requirements, costs and long-term productivity. While the work is ongoing, it reflects growing industry interest in understanding how early-life decisions shape future herd performance. 

For most farmers, the opportunity lies in the early weeks of a calf’s life. Increasing feed during this period can take advantage of naturally high feed efficiency, supporting stronger growth from every litre fed. It’s a reminder that the fundamentals still matter ‒ monitor growth, identify setbacks early and keep youngstock tracking towards their targets. 

The results may not be visible this season, but they could still be showing up years from now. The calves being reared this spring are already laying the foundations for the herd you’ll be milking in the future.

Looking for more practical advice on calf nutrition, feeding and management? Get in touch with your local Farm Source team.

Article supplied by NZAgbiz

^1. www.dairynz.co.nz/media/g1tgh3ed/technical_series_june_2012.pdf