Case Study: Early Weaning at Sanderson Bros
- ASHEEP & BEEF
- Feb 23
- 5 min read
Sarah Brown, ASHEEP & BEEF
The final breeding season has wrapped up for ASHEEP & BEEF’s Optimising Age of Weaning Cattle project, facilitated by Dr Enoch Bergman (Swans Veterinary Services) and funded through the Meat & Livestock Australia Producer Demonstration Site (PDS) program. An interesting PDS with some useful learnings – though not always those we expected!
This PDS was driven by producer interest in whether calves were being weaned at the optimal age, and whether earlier weaning than traditional timings could deliver good calf weight gains, improved management of cow condition, better feed utilisation (with less feed required when cows and calves are managed separately), and the potential to increase carrying capacity.
Demonstration sites were run over three breeding seasons (2023, 2024 and 2025). At each site, half of the calves from a group of young cows were weaned 60 days earlier than the producer’s usual practice. Calf weight gain, cow weight gain and cow body condition were measured.
Six producers were involved in the first year, with four continuing across all three seasons.
Case Study: Early Weaning at Sanderson Bros
Jonathon Thomas is Farm Manager at Sanderson Bros and hosted a demonstration site for all three years of ASHEEP & BEEF’s Producer Demonstration Site (PDS) Optimising Age of Weaning Cattle. The project was funded by Meat & Livestock Australia (MLA) and facilitated by Dr Enoch Bergman (Swans Veterinary Services). Demonstrations were conducted at Sanderson Bros’ Shark Lake property in Monjingup, near Esperance on Western Australia’s south‑east coast, where the business primarily focuses on cattle production.
With the final year now complete, we caught up with Jonathon to discuss the results and key learnings from the site.
Farm Background Snapshot
● Location: Monjingup (Shark Lake)
● Farm Size: 450 ha
● Average annual rainfall: 550-600 mm
● Annual rainfall to date (as of 23 Feb): 20 mm
● Soil type: Sand
● Enterprise mix: Shark Lake farm is mainly cattle, 1 paddock of hay
● Feedbase: Perennial pasture
● Cattle: Angus, 160 breeders
Farm & cattle program overview
“Sanderson Bros is a third-generation family-owned farm enterprise that includes cattle on Shark Lake Farm, as well as sheep and crop at another property in Grass Patch,” said Jonathon.
“The cattle program has key focuses on easy calving and high growth genetics. We sell steers as weaners and keep heifers as replacements. We run tight calving windows, aiming for 3 weeks.”
Key dates in Sanderson Bros’ cattle program include calving on 1 March, bulls in on 29 May for 9 weeks, artificial insemination (AI) for heifers and first-calvers on 20 May. Pregnancy testing is 6 weeks after the AI date for the heifers, and for the cows it is 6 weeks after the bulls are out. The time of weaning is seasonally dependent, generally in October / November. Steers are sold before Christmas as well as empty cows and surplus PTIC [pregnancy tested in calf] cows and heifers after pregnancy testing.
One of the key reasons for time of weaning being in October / November is that it needs to happen before harvest.
Overview of how the demonstration ran at Sanderson Bros
“We took part in this PDS after Enoch asked us to participate, we were curious to see if weaning earlier would work for us,” said Jonathon.
In the first year of the PDS (2023), half of the randomly selected calves (divided based on odd and even ear tag numbers) were yard weaned 61 days earlier. The animals were run on pasture, spring was notably dry. All cows and calves were weighed and the cows were body condition scored. All cows and calves were then reweighed and cow body condition score estimated again when the remainder of the calves were yard weaned. Cows were also wet/dried at that point to attempt to identify the dams of the early weaned calves. Data was summated for cows and calves identified as either early weaned, or traditionally weaned.
In 2024 and 2025 the process was repeated. 2024 saw another dry spring, however seasonal conditions improved in 2025 with wetter spring condition and increased grass growth.
Heifers were used for all three years of the demonstration.
“The weaned calves were yard weaned on oaten hay for 7 days,” said Jonathon. “They received Beachport Green Cap liquid mineral supplement during weaning in their trough. We ran them through the yards / crush every day to get them comfortable with being handled.”
“We left the cows whose calves were early weaned in the mob with the later weaners. They ran on pasture for all three years and in Year 2 and 3 they also had Beechport Green Cap in their trough.”
Observations
“Across all years of the demonstration the earlier weaned calves had less weight gain and lower growth rate than the later weaned calves,” said Jonathon. “Each year we also saw that the body condition was higher on the cows that were earlier weaned.”
Jonathon compiled a complete data set of 12 early weaned calves and 9 traditionally weaned calves over 5 data points from the 2024 cohort of calves, including the point of early and traditional weaning. The calves which had been weaned early had initially lost 15.2 kgs more than their siblings which had not been weaned up until the date the remainder of the calves were weaned, however, they slowly and consistently reduced the disparity to 8.2 kgs of difference 5 months later. [See Figure 2]
Have you modified your target weaning date as a result of the PDS?
“No, we have not changed our targeted date range,” said Jonathon.
Are there things you think you could change in future to get a better result, and any advice for other producers looking at weaning earlier in dry seasons?
“Having a higher food availability / grazing crops and silage would help with earlier weaned calves weight gain,” said Jonathon. “We’ve learnt that calves need more feed post-weaning. My key advice would be to feed more.”
What are your other focuses for taking the Sanderson Bros beef enterprise forward?
“One of our main focuses is having more fertile genetics, with better feet. We are also looking at making more bailed silage.”
A couple of YouTube video recommendations!
Many thanks to Jonathon and the team at Sanderson Bros for their involvement in this PDS. Following are links to a couple of YouTube videos that may be of interest, both from Dr Enoch Bergman’s “Enoch the Cow Vet” channel:
“Lacey Thomas - Australia’s Youngest AI Tech”: A short video of Jonathon’s daughter Lacey assisting Enoch to artificially inseminate a cow! https://youtu.be/lxXjEe0HBcI?si=erGOfG3C-ErTHsJe
“Bull or Heifer Foetus?”: Preg testing using an Easi-Scan remote display with the Sanderson Bros team, including Johnathon, wife Victoria, daughter Lacey, and staff Charlie and Ben. Great to see!
