Regional combinations study links beef genetics, growth path and profit

Why the question mattered to southern beef producers#

Profit in a beef herd depends on matching genetics, feeding and calving pattern to what buyers actually pay for, and the paper notes that upper limits are set by genetic potential while management and product value determine how close an enterprise gets to them. By the time this work began, breed societies were publishing Estimated Breeding Values for traits such as retail beef yield and intramuscular fat, but producers had limited region-specific evidence on how sires selected on those values, combined with different growth rates or calving times, actually performed once carcases reached the chiller.

The Regional Combinations project set out to fill that gap by running a coordinated experiment across a deliberately wide range of environments rather than a single research station, so that results could be examined both within and across sites and checked for genotype by environment effects. This meant the same broad question, about genetic and growth path combinations, could be tested against the particular market and production system typical of south-western New South Wales, Victoria's Western District, the South Australian Limestone Coast and the south-west of Western Australia. More on this network of trials and related regional beef work sits within this index's beef CRC conference collection.

How the regional beef systems project was designed#

Matings began in June 1999 at six locations: Darlington Point in New South Wales, Hamilton in Victoria, Naracoorte in South Australia, and Wagerup, Pinjarra and Vasse in Western Australia. Sires were grouped into three carcase categories. High retail beef yield types came from Charolais, Limousin and Belgian Blue breeds, plus Angus chosen on high yield EBVs. High intramuscular fat types came from Black Wagyu and from Angus chosen on high fat EBVs. A third category, high for both traits, drew on Angus selected on both sets of EBVs and on Red Wagyu.

Not every breed or sire appeared at every site, but many sires were shared across locations, which created the genetic links needed to combine results statistically. Post-weaning growth was managed as three broad paths: a high growth path targeting 0.7 to 1 kg per day, a moderate path targeting approximately 0.5 to 0.6 kg per day, and, in Western Australia only, a period of post-weaning weight loss followed by compensatory pasture growth. South Australia ran one growth path, New South Wales and Victoria each ran two, and Western Australia ran all three.

Carcase data were collected using AUS-MEAT chiller assessment standards, and striploin samples were assayed for intramuscular fat plus shear force and compression. Meat Standards Australia feedback data were used to generate predicted eating quality scores, while consumer taste panel results were still pending at the time of this paper. In Western Australia and Victoria, calving time, autumn versus a winter or spring pattern timed to pasture growth, was built into the design alongside genetics, allowing the combined effect on management cost and profitability to be examined.

Sire genetics and meat quality in New South Wales#

At the New South Wales site, 42 sires from Angus, Charolais, Limousin and Wagyu (Red and Black) breeds were mated by AI to Hereford dams, with steers grown at either conventional or accelerated rates to a group mean feedlot entry weight around 400 kg before a common 100 day feedlot finish. The results showed genotype mattered more than growth rate for meat quality: intramuscular fat was the only trait significantly affected by growth treatment, running higher under the faster path, while sire carcase type significantly affected shear force, compression, intramuscular fat, marble scores and predicted eating quality of the striploin.

The higher intramuscular fat genotypes ranked first or second across nearly all quality traits, while higher yield genotypes consistently ranked lowest, and shear force and compression rankings tracked closely with intramuscular fat. Even so, the paper stresses that almost all animals across all groups still achieved acceptable predicted eating quality, with most samples earning a 3 Star Meat Standards Australia rating and only three animals falling above and three below that band.

A closer look at shear force complicates the tidy story slightly: the proportion of samples above 45 Newtons, a level noted as possibly approaching unacceptable tenderness, ranged as high as 35 percent in one sire source group, hinting at lower eating quality in some cases than the model predicted. The authors conclude that high yielding genotypes can still deliver acceptable eating quality, though generally below that of genotypes favouring fat deposition, and that the economic trade-off needs weighing against actual consumer tasting data once available. Related discussion of marbling deposition in feedlot cattle appears in this summary on marbling in feedlot cattle.

Breed of dam adds another layer in Victoria and South Australia#

At Hamilton in Victoria, 39 sires representing the same three carcase categories were mated to straight-bred and crossbred Angus and Hereford cows, with dams themselves drawn from eight different genotype combinations from an earlier multi-breed project. Sire carcase type again shaped carcase weight, marbling and yield as expected, with Wagyu-sired progeny lighter and Angus selected for high intramuscular fat producing generally the highest marble scores. But breed of dam also mattered: European cross cows, particularly Limousin cross Hereford, produced higher yielding progeny, while Limousin-cross dams tended to produce progeny with lower marble scores.

Notably, no significant sire-type by dam-breed interactions were detected for any carcase parameter, which the authors interpret as meaning that sires selected through the BREEDPLAN evaluation system should produce a broadly consistent outcome for the selected trait regardless of which dam breed they are mated to. That is a reassuring finding for commercial operators who cannot easily control dam genetics on a year to year basis.

At Struan Research Centre in South Australia, 35 sires representing the same three categories were mated to a range of female genotypes, again without applying different nutritional treatments at this site. Sire carcase type significantly affected carcase weight, eye muscle area, fat depth and carcase value, and the breed of the dam's sire also significantly affected eye muscle area and fat depth, with Simmental cross cows producing calves with greater eye muscle area and the lowest fat depth, and data suggesting higher carcase value in that group.

Matching calving time to pasture growth in Western Australia#

The Western Australian component tackled a different lever on profitability: when cows calve relative to pasture growth. In the Mediterranean-type climate of the south-west, traditional calving falls in late summer and autumn, a period when pasture is typically short and poor, forcing large amounts of supplementary hay onto the system. Using three years of data from the ALCOA Farmlands site, the paper compared this traditional pattern with calving shifted to winter or spring, synchronised with pasture growth, building an economic model around measured pasture energy supply and cow and calf energy demand.

Supplementary hay averaged 629 kg per cow for autumn calving against 133 kg per cow for winter calving, with autumn cows fed 5 kg of hay per day for 150 days compared with 2 kg per day for 90 days under winter calving, hay costed at $100 per tonne. Autumn calves were heavier at January weaning, averaging 354 kg against 274 kg for winter calves, a trade-off the paper weighs against the feed savings.

Modelled at an equivalent stocking rate, shifting calving from autumn to winter lifted enterprise operating profit from $90,341 to $94,795, with cost of production per kg sold falling from $1.28 to $1.21. When stocking rate under winter calving was increased by approximately 10 percent to 10.0 DSE per hectare, operating profit rose further to $131,197, with cost of production down to $1.13 per kg sold. The paper attributes these gains chiefly to reduced feed costs, since revenue per hectare in the higher stocked winter scenario ended up similar to the original autumn system.

How much weight these regional beef systems findings can carry#

The scale of this work, six sites across four states with shared sires providing genetic links for combined analysis, is its main strength, letting the authors distinguish genotype effects from site-specific noise more confidently than a single-location trial could. But several results are explicitly flagged as preliminary: sensory taste panel data, which the authors treat as the ultimate test of eating quality beyond laboratory shear force and marbling proxies, had not yet been analysed at the time of writing, and the economic consequences of trading yield for quality were still to be fully worked through.

We would treat the Western Australian calving economics as the most immediately actionable finding, since it rests on a directly built financial model with concrete inputs on hay use, weaner weights and stocking rate, whereas the multi-site carcase quality comparisons, while statistically significant in places, involve differences the authors themselves describe as not large and still awaiting consumer validation.

The absence of significant sire-type by dam-breed or growth-path interactions across sites is also worth taking at face value only as far as the traits and environments tested; the paper does not claim this generalises beyond the specific crosses and regions involved.

What the findings suggest for herd decisions#

For producers weighing sire selection, the consistent message across New South Wales, Victoria and South Australia is that yield and eating quality traits move in partial opposition: sires selected for high retail beef yield tend to produce leaner, slightly tougher carcases, while those selected for high intramuscular fat rank better on marbling and predicted palatability but typically lighter or lower-yielding. The paper's view is that greater output from high yielding types is unlikely to be cancelled out by quality losses unless premiums and discounts for quality traits rise well above levels current at the time.

The Victorian and South Australian results add a practical point often overlooked in bull-buying decisions: dam genetics measurably shift carcase weight, marbling, yield and eye muscle area, and because sire-type effects held steady across different dam breeds, choosing sires on the BREEDPLAN evaluation system looks reliable regardless of cow genotype, even though changing cow genetics is acknowledged as slower and potentially costlier than changing sires.

For calving decisions specific to Mediterranean-type environments like south-west Western Australia, the data support shifting calving to align with pasture growth as a way to cut supplementary feed costs, with the added possibility, based on local experience rather than measured price data, that the lighter winter-born weaners might attract a premium from lot feeders. Full conclusions on genotype and growth path combinations, the authors note, await the sensory eating-quality results and detailed economic analysis still to come from this project, described more fully in the underlying design work summarised in this record of related CRC beef work in WA.

Sources and further reading#

• Trove library search: find a library that holds the paper
• Meat & Livestock Australia: red meat industry research and marketing body
• BREEDPLAN genetic evaluation: genetic evaluation system for Australian beef cattle
• Animal Genetics and Breeding Unit

Questions#

— The Livestock Library team