Australia’s rangelands cover nearly 75 percent of the continent, supporting grazing enterprises across approximately 58 percent of that area. In these extensive systems, highly variable rainfall and limited ability to manipulate the feedbase pose significant challenges for livestock producers. While environmental management remains important, genetic selection offers one of the few levers producers can reliably pull to improve herd performance. At the recent International Rangelands Congress in Adelaide, Professor Wayne Pitchford of the University of Adelaide presented findings from the Beef CRC Maternal Productivity Project, underscoring the critical role of maternal genetics—particularly weaning rate, body condition and reproductive efficiency—in driving profitability under rangeland conditions.
Rangeland Production: Environment vs. Genetics
Environmental Constraints in Extensive Systems
Rangeland environments are characterised by erratic rainfall, sporadic feed flushes and minimal supplementary feeding. Pasture growth may explode after a deluge but then wilt under prolonged dry spells. Producers in these regions have little control over feed quality and quantity, making it difficult to sustain target growth rates or body condition purely through management interventions.
The Rising Importance of Genetic Selection
Given these constraints, genetic selection becomes the cornerstone of productivity. By choosing cattle whose inherited traits confer resilience to fluctuating feed and enable consistent fertility and calf survival, producers can build herds better adapted to the realities of the rangelands. Professor Pitchford’s overview highlighted how targeted use of Estimated Breeding Values (EBVs) for key maternal traits can deliver measurable gains in weaning rate, the primary driver of profitability in extensive operations.
Weaning Rate: The Key Profitability Metric
Defining and Measuring Weaning Rate
Weaning rate measures the proportion of calves born that survive to weaning. Unlike stand-alone indicators such as conception or calving rate, weaning rate captures both fertility and calf survival in a single metric. A high weaning rate indicates not only that cows conceive and calve regularly but also that their calves thrive through the critical early months.
Weaning Rate’s Impact on Enterprise Returns
Analysis of large beef-production datasets within the Beef CRC Maternal Productivity Project showed that weaning rate explained 37 percent of the variation in maternal productivity across commercial herds, compared with just 9 percent attributed to calf weight at weaning. While higher weaning weights can boost short-term returns, it is the total number of calves weaned each year that delivers sustained profitability, especially when feed resources are limited.
Translating Concept into Practice
Despite broad recognition of weaning rate’s importance, many producers struggle to incorporate it into selection and culling decisions. Professor Pitchford emphasised the need for routine recording of calf survival and accurate parentage tracing—prerequisites for calculating weaning rate at the mob and whole-herd level. Once data are in hand, selection pressure can be applied to EBVs for fertility and maternal ability to improve weaning performance over successive generations.
Heifer Growth and Conception Strategies
Heifer Weight Gain: Critical for First-Joining Success
For heifers, the interplay between weight, growth rate and conception is well-documented. Data from over 14,000 commercial heifers showed that rapid liveweight gain—greater than 1 kg/day—during joining significantly increases conception rates, even for lighter heifers under 300 kg. This finding underscores the importance of seizing post-rainfall feed flushes to drive heifer growth ahead of breeding.
Joining Thresholds in Feed-Limited Seasons
In seasons of poor pasture response or overgrazing, meeting growth targets becomes challenging. Under such conditions, heifers must reach a minimum liveweight of around 350 kg at the start of joining to maintain acceptable conception rates. Heifers failing to meet this benchmark risk non-pregnancy, delaying their entry into the breeding herd and reducing lifetime productivity. Producers can therefore use EBVs for growth rate alongside monitored weight gains to optimise heifer joining strategies.
Body Condition Score: A Maternal Resilience Indicator
The Role of Body Condition in Post-partum Recovery
In mature cows, Body Condition Score (BCS) is the foremost predictor of post-partum anoestrus and re-conception interval. Cows failing to maintain adequate BCS through lactation and into the subsequent mating season experience longer delays to first ovulation and reduced re-breeding success. In rangelands where supplementation is minimal, genetic variation in an individual’s ability to accumulate and retain body reserves becomes a critical selection criterion.
Mature Cow Body Condition EBV
To capture this genetic component, the Beef CRC project and subsequent breed-society recording schemes developed the Mature Cow Body Condition EBV. This EBV predicts an animal’s genetic potential to maintain BCS throughout her reproductive life. Importantly, about 75 percent of the genetic variation in mature cow condition is independent of carcase fat and muscle traits, meaning that reliance on finishing-stage EBVs will not reliably improve maternal resilience. By selecting sires and replacement heifers with favourable Mature Cow Body Condition EBVs, producers can build herds that better sustain fertility across variable seasons.
Net Feed Intake: Appetite vs. Efficiency Trade-Off
NFI and Feed Restriction
Net Feed Intake (NFI) EBVs rank cattle for efficiency—animals genetically predisposed to consume less feed per unit of weight gain. In feed-abundant systems, lower NFI may translate to reduced costs. However, in extensive rangelands, a big appetite can be advantageous: animals that consume more during feed flushes build body reserves that aid survival through dry periods. Overemphasis on low-intake genetics risks undermining maternal condition and reducing weaning rate.
Balancing Feed Efficiency with Maternal Performance
Producers must therefore balance NFI traits against BCS and maternal EBVs. In some cases, a modest compromise on efficiency delivers greater returns via increased calf survival. Strategic use of EBV indexes that weight both efficiency and maternal robustness can help navigate this trade-off.
Days to Calving EBV: Enhancing Reproductive Efficiency
Defining Days to Calving
Days to Calving (DTC) EBV captures the interval from mating to calving and then from calving to re-joining. While a small fraction of its variation relates to gestation length, most of the DTC EBV variance reflects post-partum recovery and conception timing.
DTC’s Impact on Weaning Rate and Profitability
Professor Pitchford’s analysis demonstrated that every one-day reduction in DTC equates to up to a 4 percent increase in calves weaned over two joining periods. By selecting sires with superior DTC EBVs, herds can shorten calving intervals, increase annual calf crop and thus boost enterprise returns.
Integrated Genetic Selection for Rangeland Success
Prioritising Maternal EBVs
For rangeland producers, the most effective genetic strategy revolves around maternal EBVs—Mature Cow BCS, DTC and weaning rate itself—rather than a singular focus on carcase or growth traits. Recording systems must track pregnancy status, calving outcomes and weaning results to feed data into EBV calculations. Selecting bulls and heifers that excel for these traits will drive herd improvement even under extensive conditions.
Combining Genetics with Management
While genetics lay the foundation, management practices such as fencing to rotationally graze pastures, opportunistic joining after rain events and targeted supplementation during key physiological stages amplify genetic gains. Integration of measured EBVs with on-farm decision support tools ensures that selection and management reinforce each other.
Economic Case Study: Translating Genetic Gains into Dollars
Pitchford presented a case study comparing two hypothetical herds over five years. Herd A utilised sires selected solely for yearling weight, while Herd B selected for a balanced index weighting Mature Cow BCS and DTC. Herd B achieved a 5 percent higher weaning rate by Year 3, resulting in an additional 20 calves weaned per 100 cows annually. At market prices of $1,000 per weaner, this translated into $20,000 extra revenue per 100 cows, easily covering the modest premium for high-accuracy maternal genetics.
Conclusion: Building Resilient Herds for the Rangelands
While the rangelands’ environmental variability limits producers’ ability to control feed resources, genetic selection provides a powerful tool to enhance maternal performance. By focusing on weaning rate, Mature Cow Body Condition, Days to Calving and pragmatic growth targets for heifers, producers can build herds that remain fertile, resilient and profitable across seasons. When combined with sound management practices—opportunistic joining following feed flushes, condition scoring and selective supplementation—EBVs deliver measurable gains in calf production and enterprise sustainability. As Professor Pitchford emphasised, accurate genetic evaluation and disciplined selection offer rangeland producers a practical pathway to greater profitability, generation after generation.
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