Wagyu nutrition
Origins of the Wagyu breed
Wagyu breeds have unique qualities that are attributed to their origins that differentiate them from other Bos taurus breeds. Starting from the First Aurochs of the Near East, the early arrivals of domesticated cattle to Asia trace back to ancient European aurochs and migration of Northeast taurine cattle to the Korean peninsula 2,000 years ago. The origins of most Japanese breeds are from the end of the 2nd Century from Korea whilst a later strand went directly to North Japan after 1454 AD. Isolation for almost two thousand years has enabled Wagyu to have retained key differences from other breeds while they are classified to be on the extreme within the Bos taurus pool.
Establishment of Wagyu International principles for Wagyu nutrition
Research results over 20 years from Japan have been analysed to complement reading of the Japanese Beef Feed Standard 2008.
Direction changed in Japan in March 2015 with the policy of Modernizing Dairy and Beef Cattle Production to reduce dependence on imported feed. The fattening period for beef is to be reduced. LIAJ estimated that shortening the fattening period by 1 month will reduce expenses by about 5%. However, it has been acknowledged that shortening the fattening period will also reduce carcass weight and meat quality.
Global constraints
Numerous results have been reviewed by Wagyu International and the implications of reducing age of processing by increasing early growth rate are illustrated in this chart:
An increase in growth rate towards the left of the chart allows slaughter weight to be achieved at a younger age but this reduces IMF% in the lines that are darker in colour. The lighter coloured lines have higher marbling from lower growth rates.
The white line shows the conventional 2008 feed standard applied to Australian conditions. Shifting to the left reduces cost but the economics in every enterprise will dictate which coloured line will bring in the highest return.
The ratio of forages to grain determines if propionic acid fermentation predominates in the rumen during finishing and this is the basis for finishing Wagyu in Japan. By increasing forages, acetic acid fermentation predominates and butterfat production increases, so this pathway is the basis for the dairy industry.
There is a negative trend between NDF and IMF% and this is driven by the acetate:propionate ratio. Marbling increases with grain feeding during moderate growth.
Challenges of finishing on pasture
Despite limitations of marbling from finishing Wagyu on pasture for reason outlined previously, growing interest in “sustainability” of beef from grass prompted Wagyu International to venture into this aspect five years ago.
New Zealand
In New Zealand, First Light is successful and export “100% grass-fed Wagyu” to USA but they produce Wagyu cross to achieve the growth rate from pasture that they couldn’t get from 100% Wagyu offspring. First Light grass-fed Wagyu cattle are the progeny of Fullblood Wagyu bulls across traditional (predominantly Angus) beef cows and dairy (Friesian/Jersey cross) cows.
Europe
After exporting genetics from Australia to Europe, an interest in production of Wagyu from pastures developed. A collaboration with a producer finishing Fullblood and Wagyu-cross on pastures in Northern Ireland commenced five years ago. Monitoring of progress was slow initially because of environmental constraints but the drivers for productivity have become more evident.
The Australian Wagyu Association turned off access to the Estimated Breeding Value (EBV) database at 9:30pm on 2nd February 2026. After recalibration of several traits, Wagyu Breeding Values (WBV) have replaced them, and they are displayed on the Helical website. Predictions of WBVs for all Fullblood, F2 and F3 Wagyu cross steers that have been processed at Riversdale Wagyu have been determined.
A comparison has been made of the associations between EBVs as posted on 31st January 2026 and the WBVs as posted since 1st February 2026 with Margin of Fullblood steers during finishing on Pastures at Riversdale Wagyu.
Production from Fullblood and crosses on pasture at Riversdale Wagyu
Shorthorn, Angus and Angus/Friesian base females have been upgraded, and the first Fullblood females are from Australian embryos.
Recently more Fullblood embryos have been imported. Sires for beef production are home-raised and from EU and Australia.
Prices are set at retail by weight of sub primal and retail cuts.
There is no official beef grading in the UK so Wagyu International allocates scores from photographs of ribeye and sirloin steaks for each steer for the internal analysis.
Mid-parent estimated breeding values are prepared from Australian BreedPlan.
Pastures are supplemented with grain.
Financial performance is tabled, as a percentage of Full blood averages:
Financial performance by grade from pasture |
|||
Measurement/ |
Fullblood |
F3 cross |
F2 cross |
Number by grade |
10 steers |
3 steers |
12 steers |
Retail value (£) |
- |
+ 2.7% |
-7.9% |
Net profit (£) |
- |
-4.7% |
- 7.2% |
Despite a lower Slaughter Weight, Fullblood steers have a heavier Retail Weight after processing. They also have a higher proportion of higher value cuts. Wagyu crosses have a higher weight of Burgers. These factors culminate in a higher Retail Value for Fullblood steers.
Slaughter Weight and Retail Weight are charted to illustrate the breed differences of “waste” in columns in red. The sub primal/retail cuts (Retail Weight) are shown in different shades of blue colour.
Carcasses with the highest proportion of higher value retail cuts – such as fillet, sirloin and ribeye – yield highest revenue. Carcasses with a heavier weight of the high-volume burgers have lower total retail value. These are the fundamental differences between Fullblood and Wagyu cross steers - and within breed.
Average Birth weight is 10.9% lower for Fullblood steers when compared with average Wagyu crosses. Fullbloods are processed at a 5.6% higher Age with an average Slaughter weight that is 2.1% lighter than the average crosses.
Because of a higher yield from Fullblood steers, Retail weight is 3.0% higher. Fullblood Retail value per Retail weight is also 3.0% higher than crosses so Retail Value for Fullbloods is 5.8% higher. Grain supplements provided on pasture cost 17.6% more for Fullbloods and total costs overall are 4.8% higher for Fullbloods. With higher yield, Fullbloods have 5.2% lower Waste at Retail.
Overall, average Net profit per head is 6.7% higher for Fullblood steers in this dataset when compared with Wagyu cross steers finished on pasture.
Wagyu cross retail value is lower than that from Fullblood steers, so the same profit can only be realised at a higher Slaughter Weight.
Highest marble score has been scored to a son of Trent Bridge F115. Until harvested, progeny from F115 had been unpopular across Europe because of moderate growth and smaller size. However, they were subsequently found to yield higher grades and to bring heavier high-value primal cuts with higher marbling.
Fernando, son of Trent Bridge F115, maintained modest growth for almost three years on pasture then gave a growth spurt during one summer. During waterlogging he lost 76 kg over the next 28 days. He was processed at 37 months of age before recovering the lost liveweight. Two years later Fernando still has highest marble score and the lowest growth rates.
Fat Intrusion (Intermuscular fat within the muscle) is common during finishing on pasture. F3s Hardy, sired by Arubial Anticipated, weighed 800kg at 39 months.
F3a Hans, from Wyndford Sonic, weighed 825 kg at an age that two months longer.
Fullblood son from Circle 8 Bulls Q122, recorded the highest margin at 800kg at the age of 44 months.
Typically, the higher maintenance requirements for heavy steers erode the return but the yield from high value cuts from Q122 has compensated to realise highest profit.
Frequent monitoring of live weight revealed fluctuations that become more pronounced from the age of 200 days.
These variances that are caused by seasonal effects were amongst the environmental effects that appeared initially to suppress genomic expression on the pasture.
After accumulating data from five year’s production from pastures, the association in Wagyu Fullblood steers of Margin was highest with Eye Muscle Area (EMA) Estimated Breeding Value (EBV), then Carcass Weight (CW), Marble Fineness (M fine), then Marble Score (M score) EBVs. The association of Growth EBVs were weakly positive and Milk EBV was strongly negative with Margin.
The Fullblood Terminal Index has the strongest association with Margin amongst the production indices.
The associations between the new carcass trait WBVs with Margin from finishing on pasture in Europe are being monitored against the former carcass trait EBVs.
More than half of the production at Riversdale Wagyu is from Wagyu crosses.
There is a compromise of quality from sustainable production of Wagyu on pastures. However, the supply of high-quality Wagyu that is offered to the market from grass by Riversdale Wagyu is held in high regard because it usually is of the standard that would grade AUS-MEAT 9, and higher. The average Marble Score for Fullblood steers is 9.45 and 8.93 for F2 and F3 Wagyu cross steers.
Australia
A pellet was balanced by Wagyu International to supplement Fullblood Wagyu heifers and cows that are being finished on pasture on the Southern Highlands, NSW.
References
Luebbe 2014. Methane's Impact on Animal Performance - VFAs. University of Nebraska - Lincoln. March 2014.
Ogata et al., 2019. Effects of an increased concentrate diet on rumen pH and the bacterial community in Japanese Black beef cattle at different fattening stages. J. Vet. Med. Sci. 81(7): 968–974
Ogata et al., 2019. Long-term high-grain diet altered the ruminal pH, fermentation, and composition and functions of the rumen bacterial community, leading to enhanced lactic acid production in Japanese Black beef cattle during fattening. PLoS ONE 14(11): e0225448
Osawa et al., 2008. Image analysis of carcass cross-section in Japanese Black Genetic analysis of traits and meat-producing ability traits. Report posted in Japanese by Department of Bioproduction Science, Graduate School of Agricultural Sciences, Iwate University.