Origins of the Wagyu breed
The Wagyu breeds of cattle have unique qualities that are attributed to origins from the Fourth Eurochs and they were isolated for almost the first two thousand years after arriving in Japan. This 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.
Most Wagyu producers that introduced Wagyu cattle onto their cattle properties around the world had prior experience with beef production. Outside Japan, nutrition recommendations for Wagyu generally follow common practices that are applied within each country and there is a strong bias towards the principles that have evolved for the dairy industry. Most of the advances that have been made with genetics in Japan - such as the single step genomic predicted breeding values - have been adopted by progressive bodies outside Japan (such as Australian Breedplan). However, the philosophy that applies to fattening Wagyu in Japan has been more elusive to understand.
Establishment of Wagyu International principles for Wagyu nutrition
Initially research data over 20 years from Japan was analysed and some preliminary principles were adopted by Wagyu International. Subsequently the translation of the Japanese Beef Feed Standard 2008 provided additional information. Net Energy was incorporated into the tables that I generated from the Japanese requirements for Wagyu breeds.
The Japanese cattle industry requires a large component of feed that is imported and ongoing increases in production costs for beef have increased subsidies by prefecture for fattening (牛マルキン). In March 2015 the policy of Modernizing Dairy and Beef Cattle Production was announced by the Ministry of Agriculture, Forestry and Fisheries. Changes are necessary to strengthen competitiveness of beef cattle production by shortening the fattening period. LIAJ estimated that shortening the fattening period by each 1 month will reduce expenses by about 5%. I read in one survey that the average age of processing in 2015 had decreased to 28.5 months. However, it has been acknowledged that shortening the fattening period will have an impact on carcass weight and meat quality.
Historically there are abundant data from calves in Japan when they are sold to the fattening industry between 8 and 10 months of age depending on strain/prefecture. The use of digital imaging enabled additional carcass traits to be measured. Although there are differences of sex and strain of Black Wagyu, the weight for age at the calf markets is a useful indication of upbringing. The traits related to yield tend to increase when there is a higher weight for age. The average is 1.0 kg per day of age or approximately 0.9kg/days ADG from Hokkaido (Osawa et al. 2008). Individuals who exceeded this had invariably been overfed and meat quality was disadvantaged.
In order to minimise the impact on quality by the mandate to reduce age as implemented in 2015, research on feeding has been carried out extensively throughout Japan. The numerous results have been reviewed by Wagyu International. To illustrate the effect of ADG and the time to reach the same end-point, different growth rates are charted through to reach processing weight by predicted marbling (IMF%):
An increase in growth rate towards the left of the chart reaches slaughter weight at a younger age but this reduces IMF% concurrently towards the left in the different coloured lines. The darker shaded lines have lower IMF% and the lighter lines have higher marbling.
The white line shows the conventional 2008 feed standard applied to Australian conditions. Of course, marbling to this extent is not rewarded by the prevailing price grid outside Japan except for isolated niche markets. Shifting to the left reduces cost but the economics in every enterprise will dictate which coloured line will bring in the highest return.
Fundamental principles of Wagyu International's "pre-2015 Japanese feeding model"
The primary energy sources for beef cattle are starch and cellulose. They are fermented by microorganisms in the rumen to produce volatile fatty acids and gases. The major VFAs produced are acetate, propionate, and butyrate and the type of diet, microbial species present in the rumen, and ruminal pH are the major factors that influence the percentage of each VFA produced.
The loss of energy in heat and methane during the conversion of starch and cellulose to VFA makes the process of fermentation inefficient. When acetate is produced in the rumen there is a loss of one carbon as CO2which can be used to form methane. Butyrate is produced when two acetate molecules are combined so even though butyrate does not produce CO2 which can be converted into methane directly, the CO2 is produced when the acetate molecules were formed. Propionate is the only VFA that does not release an extra carbon that can be used for generation of methane. Because of these differences in carbon, the energy values for the VFA are approximately 109% for propionate, 78% for butyrate, and 62% for acetate. Therefore, increasing propionate within the rumen will decrease methane production and increase animal performance for beef production.
The Wagyu breed thrives on roughage and Japan was traditionally supplied at an age that exceeded 30 months. The balance of forages and grain that provided optimum performance and beef quality culminated in propionic acid fermentation during finishing. On the other hand, the dairy industry relies on butterfat production and this is favoured by acetic acid fermentation.
Ogata et al., 2019 monitored VFA composition in Black Wagyu in Japan that had been raised on a long term high-grain diet. From the data, Wagyu International prepared this chart to illustrate the extent to which the Wagyu breed adapts to the propionic acid type of fermentation:
The acetate:propionate ratio during the growth/Early fattening stage is 3. The proportion of propionate increases during the next two stages and the ratio moves towards 2. The losses during fermentation over the peak fattening period from the release of methane is reduced so this makes it the most efficient use of resources.
The pH levels in the Early and Middle stages in this trial were similar to those that were reported during a feeding trial with Holstein dairy steers in Japan. Ogata suggested that a lowering of pH and total volatile fatty acid production occurred during the ‘Late’ fattening stage with Black Wagyu. However, the ruminal bacterial community adapted by preserving their diversity or altering their richness, composition and function. The author observed “the cattle showed no clinical sign of abnormal body condition, such as high body temperature, acute feed intake, dehydration, and diarrhoea, throughout the study period, and the body weight ... showed a gradual but significant increase across the three fattening stages. Dietary intake amounts were highest during the Middle stage and lowest during the Late stage as an adaptation to long-term high-grain diet feeding or response to significantly lowered ruminal pH during the latter fattening stage. However, growth performance during the Late stage was not impaired, and changes in the 24-h mean ruminal pH were not consistent with dietary intake or rates of DM and TDN (energy).”
This is the first study that demonstrated the relationship between the long-term high-grain diet feeding with bacterial diversity and richness, and suggests that long-term high-grain diet consumption results in the preservation of bacterial diversity to protect against an imbalance of the entire rumen bacterial community in Japanese Black Wagyu cattle.
In the same year, Ogata and co-workers published a paper after the proportion of concentrates had been increased above conventional fattening of Wagyu in the Middle and Late stages. The acetate: propionate ratio of the VFA decreased from 2.37 in the Late stage with conventional feeding to 1.47 with additional concentrate but these effects were not statistically significant. There were contrasting results with the pH levels but those differences were not significant. Clinical symptoms such as anorexia, fever, and diarrhoea were not observed in any periods of both groups. The authors concluded that the rumen of the Japanese Black beef cattle adapted to long-term feeding of a high-concentrate diet.
Steve Bennett points out he does not advocate feeding Black Wagyu to the extremes tested above but he has shared these results to show the adaptation that has been demonstrated by Black Wagyu to these conditions. Research data from fattening trials in Japan have been reviewed by Wagyu International from the last ten years. Other treatment effects were being evaluated but the association between NDF and IMF% across various treatments is illustrated:
A negative trend between NDF and IMF% is indicated and is quite flat here but the association was stronger for polynomial regression (R2 = 0.4336 for the Middle fattening stage, not shown). However Wagyu International cautions that this response was obtained while the principles of conventional Japanese fattening were applied so caution is required if excess fat or energy and energy is provided commercially. Optimum results are only achieved from a balanced approach commencing from conception. Accordingly Wagyu International recommendations for backgrounding through to finishing have been balanced through each stage within maximum and minimum growth rates, protein, energy, NDF, ADF and starch whilst satisfying the major micro-nutrient requirements. The standards that apply are referred to as its “pre-2015 Japanese standard”.
As always, the economics and end points are different in every enterprise so must be considered.
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.