PRIORITISING heifer performance is one of the key components in any successful breeding business.

The challenge for producers, particularly in extensive rangelands areas is often finding practical and regionally-relevant information to shape decisions around heifers and their management.

In extensive areas, where typically heifers comprise up to 40 percent of the breeding herd, under-performance can have a significant impact on the overall productivity and profitability of the enterprise.

Although strategies for heifer management have been well established, and supported with resources such as MLA’s Tips & Tools, publications such as Heifer Management in Northern Breeding Herds and Managing Phosphorus in Beef Cattle Diets; the practical application of strategies has remined low in many areas.

The Desert Uplands Committee based in western Queensland, representing an area encompassing regions from Barcaldine to Alpha, Aramac and Jericho established a research project titled Girl Power: Prioritising Heifer Performance.

The Girl Power project was led by CHRRUP Ltd and supported by Meat & Livestock Australia, in collaboration with the Desert Uplands Committee and technical partners including the Queensland Department of Agriculture and Fisheries.

The goal was to demonstrate how structured, regionally-adapted management strategies could improve the reproductive performance of maiden heifers and first-calf cows in extensive systems. The project ran from 2020 to 2024, with the final report published recently by MLA.

Structured heifer management

The project involved 12 commercial beef businesses. Three of these were formal Producer Demonstration Sites, while the remining nine acted as core collaborators.

Over the course of the project, data was collected on three age cohorts of heifers. The data included liveweight, joining and calving outcomes, nutritional status, as well as herd management practices.

As a result, the GirlPower project identified that while most of the producers engaged had a strong intuitive understanding of their systems, structured heifer management was rarely applied.

In 2020 when the project started, 10pc of participants had a documented heifer management plan, and activities such as pre-joining weighing, pregnancy testing, or assessing body condition at calving were inconsistently implemented.

One of the significant outcomes presented in the report was the increase in structured management practices. At the conclusion of the project, 88pc of producers were regularly weighing heifers prior to joining and conducting annual pregnancy testing.

In addition, 87pc of producers engaged in the project had begun assessing body condition at calving.  At the start of the project none were using this strategy.

Overall, the project saw the number of producers with a formal heifer management plan increasing to 75pc, with 20pc fully implementing their plan on-property within the project lifetime.

The project results were a significant factor in these improvements in management strategies. Across the project, the participating properties reported consistently higher weaning rates over the three cohorts, which was largely driven by improved fertility, calving ease, and calf survival. Although specific averages varied between properties, the overall trend across case study sites showed steady year-on-year increases.

Earlier cycling in both maiden heifers and first-calf cows was also observed, linked closely to better body condition management and targeted phosphorus supplementation. This led to tighter calving periods, which improved management efficiency and resulted in more uniform calf weights at weaning.

As a result, conception rates in maiden heifers exceeded 84pc across most sites, and first-calf cow re-conception rates reached or surpassed 70pc, with both outcomes well above regional benchmarks.

Body Condition Scores

As previously noted, while the value of recording Body Condition Scores (BCS) has been long advocated, the actual use of these scores prior to participation in the project was very low.

At the end of the project 87pc of participants were routinely monitoring and managing BCS, which had a significant impact on improved re-conception rates. Additionally, the project helped reenforce the value of achieving critical mating weight (CMW), with most herds targeting 330–350kg liveweight prior to joining.

This threshold, tailored to two-year-old heifers in extensive systems, proved effective in setting females up for a productive first lactation and beyond.

Although the GirlPower project was regionally focussed, the results do have application for other northern regions. The project focused on reproductive performance, but these improvements were also subjected to economic analysis using BreedCow & Dynama.

The modelling compared two real-life herd scenarios drawn from project data: one reflecting baseline regional performance (75pc maiden conception, 60pc first-calf cow reconception), while the second reflected the top-performing PDS site (93pc and 74pc respectively).

The resulting analysis showed an increase of approximately $29 per Adult Equivalent (AE), or a total increase of $80,000 across a 2660 AE breeding enterprise.

While improvements in management strategies, such as weighing and assessing BCS contributed to increases in productivity, the GirlPower project also demonstrated the importance of the phosphorus supplementation.

Again, phosphorus deficiency is not a new issue in northern production systems. However, the use of strategic supplementation is potentially much lower than many producers would have assumed.

At the start of the project, only 63pc of producers were supplementing with P during the growing season, although testing confirmed widespread P deficiency across participating properties, with Colwell P values commonly between 0–9 ppm.

It is generally recognised that the critical threshold for grazing systems is between 10-15ppm (depending on soil type and pasture species). Below this level, phosphorus availability becomes limiting, particularly during the growing season, and can significantly reduce animal growth, fertility, and milk production.

Once testing revealed Colwell P levels well below critical thresholds, the project participants were able to clearly link low fertility and weight gain to nutritional constraints.

As a result, 100pc of participants adopted P supplementation by the end of the project. The inclusion of strategic supplementation of phosphorus was essential to realise the gains that more effective management practices offered in the management of heifers.

Regardless of genetics, fertility, growth and lifetime productivity will remain limited if the heifer is underfed, undergrown, or managed without structure

From a genetic improvement perspective, the Girl Power project reinforces the fact that genetic potential can only be realised when environmental and nutritional constraints are addressed.

Regardless of genetics, fertility, growth and lifetime productivity will remain limited if the heifer is underfed, undergrown, or managed without structure.

As demonstrated in the project, improving performance through phosphorus supplementation, body condition management, and defined mating weight targets, not only improves short-term reproductive outcomes.  It also creates the conditions necessary to capture long-term genetic gain.

Al Rayner

Alastair Rayner is Principal of RaynerAg and an Extension & Engagement Consultant with the Agricultural Business Research Institute (ABRI). He has 28 years’ experience advising beef producers and graziers across Australia. Alastair can be contacted here or through his website: www.raynerag.com.au