The latest on early weaning calves: Esperance demonstration results

Article by Dr Enoch Bergman, Swans Veterinary Services

ASHEEP & BEEF’s Optimising Age of Weaning Cattle Producer Demonstration Site (PDS) project –  funded by Meat & Livestock Australia (MLA) and facilitated by Swans Veterinary Services – is  wrapping up after three years of demonstrations.

The project design was simple, perhaps too simple. Enrolled producers would nominate their planned weaning date. First calving heifers were targeted and within their management group each producer attempted to randomly choose and wean half of their calves roughly two months earlier. What the PDS was trying to demonstrate is that by weaning calves earlier, feed resources could be better managed without significantly reducing the calves’ weight for age by the traditional weaning date.

Calves divided into two groups at Carnigup in 2025, one of the PDS demonstration sites. Photo: 23 October 2025, at the date of the earlier weaning.

The concept of earlier weaning is rooted in good science and has been advocated across many beef and dairy production systems. Milk is an incredibly expensive product for cows to produce. Newborn calves are quite skilled at extracting value from their mother’s milk, able to extract roughly 90% of the energy donated to them by their dam. However, as calves grow, their rumen begins to develop preparing them for a life of eating grass. Once the calf is around 4 to 5 months old, or around 150 kgs, the calf is no longer able to digest milk as effectively, instead degrading much of it within their developing rumen, wasting almost half of their mother’s energy investment.

Ruminant nutritionists have noted that a cow and calf separated require just under 40% less energy derived from dry matter to maintain the cow’s weight and to keep the calf growing than if they are co-grazed. The caveat to this simple equation is that young growing calves are far more susceptible to suffering poor growth outcomes if protein levels in their feed on offer falls much below 16 to 17 percent.

Conceptually a producer’s goal could be to calve with feed, ensuring that peak milk production of cows is co-ordinated with peak digestibility by their calves, wean early enough that feed is still of high quality, and partition feed resources so as to look after the calves at the expense of the feed offered to the breeding herd.

The initial demonstration design did not involve having enrolled producers manage the dams of the calves differently (the early weaned calves were drafted off from the herd whilst the remaining unweaned calves and all the dams continued to be managed together until the second weaning event). Regardless, the dams whose calves had been weaned earlier (identified by wet drying all of the cows at the traditional weaning event), were both consistently heavier and had better body condition scores than the heifers whose calves remained on them for a longer time frame.

The PDS ran over 3 years, began with 7 sites and finished with 4 sites for a total of 15 data sets. One site (in the first year) showed improved weight gains amongst the early weaned calves as compared to their unweaned siblings, however, on the remainder of sites, the earlier weaned calves were consistently lighter and in some cases much lighter by the time of the second weaning event. Calves weaned earlier ranged from 0.7% heavier to 16.3% lighter compared to their siblings weaned later with an average reduction in weight at the second weaning event of 5.8% or 18.2 kgs. The cows comparatively were 16.5 kgs heavier if their calves had been weaned earlier.

A single producer, in the final year of the project, was able to identify most of the dams of the early weaned calves and manage them separately.  He then moved those cows to a paddock of dry feed at a stocking rate of three cows to the hectare.  The remaining cows and the unweaned calves were maintained on excellent green feed at a stocking rate of one cow to the hectare.  He was still able to maintain almost identical body weight and body condition scores between the two classes of cows.  The calves which were weaned earlier onto good feed were just under 10kgs or 3% lighter than the unweaned calves at the second weaning event.

Overall, the enrolled producers felt that the PDS clearly showed to them the impact that nursing calves have on the weight and body condition score of their mothers. They felt that it has improved their confidence in weaning earlier when conditions require and that they gained a better appreciation of the feed requirements calves would need if they were to be weaned earlier. Further, it was noted that producers who traditionally sell their calves at or close to weaning were much more likely to be financially impacted than those who background or grass finish their calves. Some sites have shown the gap between the heavier later weaned calves and their early weaned siblings has been narrowing over time and believe that by the time they market their calves as grass finished or as replacement heifers that there will no longer be able to discern the difference.

We will be excited to share some of the findings of the PDS in our next ASHEEP & BEEF newsletter once the final results have been compiled. In the meantime, below are some of the things we have learned.

1. Cows whose calves are weaned earlier maintain better weight and body condition.

2. Calves weaned earlier usually require some form of supplementation to maintain the growth rates of unweaned calves.

3. Tailoring your weaning date based on the body condition score of your breeding cows, your feed on offer, and seasonal forecasting is a good management tool to protect your breeding herd.