Factors influencing, and selection for, eating quality in Wagyu beef

This paper is a review of both genetic and nutritional technology that can be harnessed to improve eating quality of Wagyu beef and has been written in response to questions that have been fielded from the global Wagyu community.
Genetic progress in Japan since the 1960s is reviewed. The reliance on imported feed for livestock in Japan is influencing Wagyu production so import data, pricing and consumption is presented.
The principles that determine ultimate eating quality are reviewed so that production can be adapted in numerous marketplaces at a time that sustainability constraints are also impacting.

BLUP analysis in Japan

A step back in time to review progress from genetic gain in Japan is the starting point (Sasaki et al, 2006). Prior to 1968, visual assessment to select Wagyu for breeding was based on the principle that soft and elastic hide, fine and soft hair, fine textured horn, and clean-cut face would produce high quality beef. In 1968 this changed when a testing system was adopted using a test station within each prefecture for both performance and progeny testing of the young bulls. There were three steps that were involved: Initially, candidate bulls produced from planned mating using superior sires and dams that had been selected on visual judging were gathered and performance tested for 112 days at a prefectural test station after weaning. Based on their growth rates, the best young bulls were selected for test mating. Progeny (6 to 10 animals) were performance tested over 364 days. From these, the best bulls were selected based on the carcass records from their progeny.
This process continued but, in the late 1980s, three prefectures (Ōita, Hyōgo, and Kumamoto) began on-farm progeny testing based on best linear unbiased prediction (BLUP) within each prefecture by entering carcass records from carcass markets and pedigree records from registry associations. Under this program, all sires and dams of the steers and heifers shipped to the carcass markets were simultaneously evaluated. The predicted breeding values from the BLUP analysis were used for planned mating between superior sires and dams. This resulted in the production of candidate bulls. Furthermore, on-farm culling for breeding dams, which were based on breeding values, was introduced. Until then, selection had been entirely focused on the sire. On-farm progeny testing became popular and was rolled out in additional prefectures. Initially, the primary selection for the Japanese Black bulls was on carcass quality traits while selection for the Japanese Brown breed was based on growth traits. After favouring growth for several years, carcass quality was selected for in Japanese Brown but their large size has prevailed through to the Japanese Brown of the present.  
The rate of genetic improvement in Wagyu in Japan under the three historic methods – visual assessment until 1968; then progeny testing at prefectural stations through to mid-1980s; and finally on-farm progeny recording for BLUP analysis that were recorded through to 2003 – is reported. The three regions where breeding merit was measured are Kumamoto on Kyūshū Island (Japanese Brown/Red Wagyu/Akaushi), Hyōgo on the mainland with Tajima strain of Japanese Black, and Ōita which is next to Kumamoto on Kyūshū Island acquired several sons from Dai 7 Itozakura for the Japanese Black herd.
Average carcass performance from the two breeds from three prefectures in Japan:





Japan Brown

Japan Black

Japan Brown

Japan Black







Carcass weight (kg)






Loin area (cm2)






Rib fat thicknness (mm)






S.c. fat thickness (mm)






BMS grade






Fattening period (days)






Slaughter age (days)






Japanese Black in Hyōgo had greater marbling (BMS) than Japanese Brown, but with a longer feeding period which resulted in finishing at an older age (P < 0.001). The Japanese Black steers in Hyōgo had thinner subcutaneous fat thickness and smaller carcass weight than Japanese Black from Ōita, but the growth performance in Ōita was superior to that in Hyōgo. Japanese Brown had higher carcass weight than Japanese Black from a shorter feeding period.
Moderate to high heritabilities (h2) were obtained for all carcass traits for the three prefectures: Carcass weight 0.44 to 0.50, rib fat thickness 0.40 to 0.47, loin muscle are 0.44 to 0.54, subcutaneous fat thickness 0.50 to 0.57 and marbling (BMS) 0.56 to 0.64. Generally, heritability was lower for traits for Japanese Brown in Kumamoto and for Japanese Black in Ōita, and was highest for Japanese Black in Hyōgo.
Pedigrees for the 126,937 animals in the study were traced back to ancestors that were born in the 1950s. Wagyu cattle in Japan had been used as draught animals for centuries but became increasingly important as beef animals during 1960s. By 1968, performance and progeny testing were introduced to the beef industry in Japan.
Genetic trends were estimated by averaging predicted breeding values of dams that were reproducing and that had calves that were born during the same year in each prefecture. Genetic gain per year during the period of visual judging was small. Genetic gains in the period during the progeny testing in prefectural test stations increased for most traits. After adopting on-farm progeny testing with BLUP analysis, genetic changes for all carcass traits became significant.

Chart of Genetic gains of marbling of Japanese Black in Japan per yearChart of genetic gain of loin area in JapanChart of genetic gain of subcutaneous fat in Japanese Black and Japanese Brown from visual selection, progeny tests then on-farm BLUP analysis

The results clearly show the ineffectiveness of visual assessment that was applied in the first phase for three carcass traits in the charts above. The response to “Visual selection” until 1968 is shown in the group of three bars to the left of each chart.
Improvement from progeny testing in test stations in the middle phase for a few traits is shown in the middle cluster of bars above “Progeny – on station”. Among them, BMS in both Japanese Black populations and carcass weight in the Japanese Brown were most notable. Interestingly, positive trends in these cases began simultaneously around 1978, which was about 10 years after performance and progeny testing commenced in test stations. Beef marbling in Japanese Brown only became an important objective in the late 1970s so larger improvements in genetic gain for BMS in Japanese Brown only began to be demonstrated during the 1980s. In Hyōgo prefecture, a strong negative trend was evident in subcutaneous fat thickness during the progeny testing. After an increase in subcutaneous fat thickness in Japanese Brown in Kumamoto during the first two phases, it was strongly reduced during the final BLUP analysis phase. These outcomes had not been specifically selected for so were incidental but nevertheless statistically significant. In addition, a negative trend is apparent for carcass weight. Hyōgo prefecture is famous for the production of highly marbled beef with thin subcutaneous fat – the notorious ‘Kobe beef’. It is important to note that a maximum carcass weight was imposed for certification as Kobe brand beef at the carcass market in Kobe city and the lighter Tajima carcasses still prevail to the modern day globally.
The on-farm progeny testing program that is based on BLUP began in 1983 in Oita, and in 1987 in Kumamoto and Hyōgo. The genetic gains achieved in the final phase from the late 1980s in these charts (right hand cluster above ‘Progeny – on farm BLUP’) suggested that on-farm progeny testing would effectively enhance the genetic improvement of all carcass traits of Wagyu populations when it is applied. On-farm BLUP analysis was rolled out to the other prefectures through Japan. Because progeny testing in test stations was continued after on-farm progeny testing began, genetic improvement in the final stage may reflect the summation of genetic improvements achieved by both programs.
The overall results indicate that genetic improvement of economic carcass traits in Japanese Black (Black Wagyu) and Japanese Brown (Red Wagyu/Akaushi) was greatest during the on-farm progeny testing program which incorporated BLUP. After the on-farm program began, predicted breeding values for breeding females became available to farmers. The benefits from the effective selection of reproducing dams based on their predicted breeding values  have enhanced genetic gains during the period when on-farm progeny testing and genetic evaluation were combined.

Progeny tests in Japan

During this period (Ono, K), the first sires that were progeny tested had the results of six (Dai 7 Itozakura) to eight (Yasufuku) progeny displayed on the registrationSites on Wagyu carcass in Japan for measurements to be be taken during grading for Yield Score Progeny test results from Yasufuku as displayed on his son Yasufuku 165-9's registration certificate in Japan in article on eating quality by Wagyu Internationalcertificates of their registered offspring. The average of +4.1 for BMS (旧 or “old system”) from Yasufuku’s eight progeny during his “indirect” test, 0.83 kg/day for daily gain, 16 mm for subcutaneous fat thickness and 49 cm2 for rib eye area is shown to the left in an extract from his leading son Yasufuku 165-9’s registration certificate. Yasufuku’s registration gave a Yield estimate of 83.4, with DG, REA and BMS. Even though this is not shown on the certificates, Yasufuku’s dressed weights were an average of 354.1 kg from an average slaughter weight of 541.8 kg at an average age of 20.5 months of age.
Semen from all sires was distributed enabling more progeny from each sire to be evaluated progressively after the initial ‘proof’. Predicted breeding values (PBVs) were calculated using BLUP analysis and reported for the top hundred or so sires in each prefecture periodically.. In addition to Carcass weight, Marbling and Rib eye area PBVs, Rib thickness PBV was reported together with the Accuracy for each trait. Rib thickness is one of several measurements that are used during grading to obtain Yield Score JMGA 2000.

Yield Score estimate (%)none               
none+ 0.300 x Rib eye area (cm2)
none+ 0.667 x Rib thickness (cm)
none-  0.025 x Cold left side weight (kg)
none-  0.896 x Subcutaneous fat thickness (cm).
An additional 2.049 is added for Wagyu carcasses. Yield score is reduced by one score if the intermuscular fat thickness is relatively thick, or if the round is too thin, and if the proportion of fore-quarters and hind-quarters is considered undesirable.
Rib thickness is the width of intercostal muscles and excludes subcutaneous fat thickness on the exterior. Subcutaneous fat is considered to be antagonistic to yield so it is multiplied by a negative factor in the Yield Score calculation in Japan. A minimum amount of subcutaneous fat is considered to be essential on the carcass so a low measurement from the progeny test is undesirable, but so too is excess because it increases waste.
Marbling (IMF percentage) content by BMS score in Japanese beef grading by JMGA in 1988 and in 2008One sire in 1989 had 20 progeny in his test but most progeny tests from the early 1990s were carried out from an average of 10 progeny. After another ten years the number of progeny used as ‘proof’ in the indirect test increased to around 20. The more popular sires have PBVs from hundreds of their progeny over time and accuracies that have been incorporated through BLUP analysis into the breeding values published by each prefecture. The results are compared within each prefecture.
The distribution of raw data for each sire has been analysed and compared with breeding values. No association was detected between BMS progeny test result from sires from the 1970s through to1980s against their subsequent breeding value. Grading of all carcasses is under the authority of JMGA and the process is continually under review. The minimum IMF% for each BMS in 1988 is a large yellow dot in the chart to the left. By 2008 it had increased and the minimum IMF% for each BMS is a white dot. Subsequently, digital imaging from the Obihiro University camera of carcasses that had been JMGA graded shows each reading as an ‘x’ (Grose 2011). Each point has merged into white bars where they are the most abundant. A large variation in IMF% values for each BMS was revealed and they are mostly above the designated minimum standard for each BMS. Progeny test results that had been graded under the former BMS are called the old system and are recorded as +4. 4(旧). Results from the modern system do not have a sign and look like this: 3.0(新).
No association was found between progeny test results from between six and 13 progeny per test against sire breeding value. An analysis was carried out with raw data from the modern BMS grading system. There was a positive trend between BMS (新) progeny tests and breeding values from tests with approximately 20 progeny (R = +0.39, yellow circles in the chart below and to the left, with a trend line in yellow). It was weaker but nevertheless positive from tests with between 6 and 13 progeny per sire (R = +0.17, white squares).
Chart of breeding value of sires versus average BMS of progeny in either 10 or 20 progeny per test in JapannoneChart Rib eye area progeny test results with REA predicted breeding values from 10 or 20 progeny per test in Japan
The standard deviation was high and it is caused by environmental influences, including maternal contribution, during progeny tests. The variation in IMF% in BMS grading would have also been a factor. The relationship between REA progeny test averages with REA predicted breeding values from the same Japanese Black sires is illustrated in the chart above and to the right. There is a positive association between REA progeny test average from ±10 progeny (R = + 0.23), but it was strong for sires with ±20 progeny in their test (R = + 0.64). 20 progeny per test appear to be sufficient to compare sires for REA breeding merit. The difference between correlations of + 0.39 for BMS and + 0.64 for REA (for ±20 progeny) may be mainly due to the inconsistencies in marbling % from BMS that have been subsequently flagged by digital analysis.
Some raw data from progeny test results from two sires with 21 progeny in each test are shown below. The narrowest spread was from the sire with an average BMS of Raw data of BMS grades from two sires on progeny test10.24. The distribution is shown by blue bars in the chart. The BMS grades were from 8 to 12, and the standard deviation was 1.18. Most divergence was from a sire with an average of 8.76, from scores of 4 to 12 in nine different grades, and a standard deviation of 2.57 (shown with yellow bars). The extent of the variation in progeny results in these two unrelated sires in Japan, illustrates how deceptive it could be to try and predict an animal’s performance from just one offspring, or five, or even ten? Accordingly, it is concluded that averages alone from 10 progeny per sire do not provide an accurate estimate of breeding merit, but that it is possible that a trend could be obtained from 20 or more progeny. However, a BLUP analysis is required to obtain reliable breeding values. The requirement for so many results per sire is undoubtedly influenced by the variance within each BMS or AUS-MEAT marble score grade in raw data unless IMF% is measured.
Breeding values have been incorporated onto registration certificates in Japan for several years on a percentile basis below the progeny test results. The breeding value of each animal is compared with the estimated breeding values within the recording prefecture. This rating permits animals from different prefectures to be compared and is displayed for females too. The Top 25% are designated to be “A”, those from 25-50% are “B”, while “C” are considered to be average or below. The group is displayed after the 育種価 in a string of six capital letters, in the following order:
Carcass weight breeding value
Rib eye area breeding value
Rib thickness breeding value
Subcutaneous fat thickness breeding value
Yield estimate breeding value
Marbling (BMS) breeding value.Progeny test results and predicted breeding values for Japanese Black sire Fukuei on a son's registration certificate
An example from a Registration certificate is the son of Yasufuku 930 and Harumi. The breeding value score on the certificate is  ‘BABCBA’. A is for Rib eye area and BMS PBVs, B is for Carcass weight, Rib thickness and Yield estimate PBVs, and C is for Subcutaneous fat thickness PBV. These PBVs align with the expectations from his pedigree. His performance test DG was 1.31 kg/day and progeny test results were DG 0.92, BMS 2.6, REA 47, and Yield 73.2%.
Finally, Japan has progressed to single step genomic BLUP. The conversion to predicting breeding value from genomic BLUP compared to pedigree BLUP has improved accuracy to the largest extent to those traits that have had lower accuracy. Accordingly, REA accuracy has improved by a third, BMS has almost doubled while subcutaneous fat thickness accuracy has increased by 130% to just over 0.5.

Present breeding value reporting in Japan

Indirect verification and on-site verification is carried out by the Japanese Wagyu Registration Association. The official record (daily gain) from the performance test is displayed for the bulls that have been tested directly.
In the field generation test, at least 15 progeny (steers and heifers) are fattened at multiple fattening farms and facilities with a shipping age of 29 months for steers and approximately 32 months for heifers. Grading is by the official graders with BMS up to 12. The overall result is the average from the sexes.
In the indirect test, at least 8 steers are raised in a test facility and feed uniformly until reaching shipping age at approximately 21 months of age. Marbling is graded on the scale 0 to 5 and the average displayed for each trait.

In-field progeny test







SC fat













































2007 progeny test with 27 sires







SC fat
























Genomic breeding values





Rib thick

SC fat























The following recessive genetic conditions are tested: B3 (Spherocystosis), F13 (Factor 13 deficiency), CL16 (Claudin 16 deficiency), CHS1 (Chediak Higashi Syndrome), MCSU (Molybdenum Coenzyme deficiency), MOD (Merle Ocular Dysgenesis eye dysplasia), IARS (IARS abnormality), FMA (Forelimb zone muscle abnormality) and BAS1 (Bartter syndrome type 1).
A recessive gene carries brown hair in Japanese Black cattle and it is detected in the MSHR test (Melanocyte Stimulating Hormone Receptor).
More recently, the registration certificates in Japan reflect advances from genomic evaluations using DNA and display the breeding value score for both parents without the progeny test results. Registration certificate for Japanese Black in Japan has breeding value scores for parentsThe example shown here is a son of Yasfukuhisa so the sire 安福久 is shown above with his Kurogen registration number 4416 and score 85.5, the performance and progeny test box is empty with the breeding value score of CACAAA below it. The dam is なつえ7 with Kurogen registration number 1102595 and score 84.0 and Radar chart of breeding values for Hanaahrufuku Japanese Black in Japanbreeding value score BCACBB. The addition of the breeding values to the registration certificates make valuable information available for breeders, but it is a very positive step to make the dam's breeding merit known too. Yasufukuhisa is the top sire from the modern era as he outperformed his father, Yasufuku 165-9, who in turn, outperformed his sire Yasufuku. His dam is sired by Monjirō, with grandsire Itohikari and Kedaka blood from Harumi. His breeding value is for carcass traits from the pick of Yasufuku breeding plus Monjirō which gives him 4 'A's for breeding values and only misses the top for carcass weight and subcutaneous fat thickness. Grandsire of なつえ7 is the inbred Kedaka sire, Dai 20 Hirashige, so is behind her breeding value of A for rib thickness, and 'B's for carcass weight, subcutaneous fat thickness and yield score. Marbling and rib eye area are both 'C'.
Breeding value is a relatively new concept for producers and they are numbers which are positive or negative. When genomic breeding values were introduced, the 'zero base' of 0 was set from the average from Japanese Black that were born from 2011. A visual aid is provided by a radar chart for promotions from the prefectures and sellers of genetics. The same six breeding values are used and are the points on the edge of the radar screen. The highest score 'H' si for the top 10%, 'A' from 10 to 25%, 'B' from 25 to 50% and 'C' is for average below 0%. The zero points are joined by a bold line (bold and broken in the example shown to the right). The exception is made for subcutaneous fat thickness when the breeding value is reversed (positive becomes negative) because excess subcutaneous fat thickness is undesirable. This example is from modern sire 華春福. The breeding value score that would be shown on his registration certificate is ABHBCH.

BLUP analysis outside Japan

The use of digital imagining as pioneered at Obihiro University has enabled carcass measurements to be recorded in countries where local carcass grading is inadequate for Wagyu carcasses (Maeda et al, 2013). Increased accuracy from measuring phenotypes increases heritabilities of some traits. In addition to that, Australia rolled out single step genomic BLUP in 2017 where EBVs for Wagyu are reported by the Australian Wagyu Association in BREEDPLAN. A few operations conduct their own EBV evaluations analysing data from either digital imaging or local AUS-MEAT carcass grading in independent BLUP analyses.
In USA, expected progeny differences (EPD) are reported by the American Wagyu Association for four traits. 113 Wagyu sires have marbling EPDs that have been generated from 4,066 half-bred Wagyu progeny that were raised in contemporary groups. It appears that a minimum of 80 progeny from the non-Wagyu dams are required to generate EPDs that have sufficiently high accuracies for a parent. EPDs have not been published for females.

Marbling and Tenderness

The supreme eating quality from the Wagyu breed is attributed mainly to ‘marbling’ which is intramuscular fat (the fat within muscle, ‘IMF’). In Japan, marbling with a fine Marbled Wagyu beef in Australiaappearance – like frost ‘Shimo-furi’- is highly valued, while coarse marbling is inferior. Marbling contributes to the tenderness of beef because IMF deposits located between muscle fibre bundles disrupt the connective tissue of perimysium. There is an average of almost 1000 flecks of fat in the cross section of the eye muscle with fine marbling so more connective tissue is disrupted.
Foundation Wagyu sires with highest estimated breeding values (EBV) for fineness of marbling are: Michifuku (+0.47),  Kitaguni Jr (+0.34), Itozuru Doi TF151 (+0.30), Itoshigenami TF148 (+0.27) and Yasufuku Jr (+0.25). The highest negatives are Itoshigefuji TF147 (-0.44), Kikuyasu 400 (-0.39) and Yukiharunami 4 (-0.37) (AWA, 2019).

Eating quality from chemical and lipid content

IMF content is generally associated with tenderness and juiciness of meat. The ‘eating quality’ of meat is more broadly determined by the sensory characteristics of texture, taste, tenderness, juiciness and aroma. In addition to IMF content, other factors have been reported as affecting the eating quality of meat, including fatty acid composition. In addition, beef palatability has been shown to be related to water-soluble compounds, such as free amino acids (e.g. glutamic acid and aspartic acid), peptides (e.g. carnosine) and nucleotides (e.g. inosine 5′-monophosphate ‘IMP’), as well as sugars (e.g. glucose and fructose). Sugars could contribute to the sweetness and flavour of meat upon cooking, due to the Maillard reaction
Improvements in the chemical traits of meat can be achieved through manipulation of both genetic and environmental factors – such as from aging, the diet and feeding system. Genetic effects in some traits have been reported; for example, fatty acid composition is a heritable trait, with heritability ranging between 0.31 and 0.73 in the Trapezius muscle, and between 0.58 and 0.78 in the Longissimus muscle of Japanese Black cattle. Most heritability estimates for water-soluble compounds were lower than 0.30 but these traits were affected by aging over a few weeks so they can be more successfully enhanced by aging than by selection.
Japanese Black cattle is able to deposit a large amount of intramuscular fat (Zembayashi et al., 1988) and M. longissimus dorsi in Japanese Black cattle is capable of containing more than 30% of intramuscular fat. The relationship between intramuscular fat and the acceptability of beef was studied by using sensory evaluation with regards to the degree of intramuscular fat and fatty acid composition. In a study on the relationship between fatty acid composition and sensory evaluation, Dryden and Marchello (1970) reported that there is a significant correlation relationship between oleic acid and flavour score. Also, Westerling and Hedrick (1979) reported that high levels of total unsaturated fatty acids and oleic acid correspond with high flavour scores.
There is a significant relationship between fatty acid composition from adipose tissue in Japanese Black and the melting point of fat (Mitsuhashi et al, 1988).
A trial by Okumura et al, 2007 with five sets of identical Japanese Black twins fed from 7 to 24 months so that one group had higher IMF% (HG) compared to the lower IMF% group (LG) from manipulation of Vitamin A intake in the diet. BMS was higher in HG (3.6) than that of LG (2.8) (p<0.05) and the crude fat content difference was modest but significant (p<0.05) at 25.8 and 23.2%. HG appeared to be more tender with lower shear force (16.3 newtons) than LG (17.6) but the difference was not significant. None of the proportions of saturated fatty acid (myristic, palmitic and stearic acid) showed any significant differences between the two groups. The proportions of oleic acid, which makes up the greatest proportion in unsaturated fatty acid in M. longissimus dorsi of the loin was 48.1% and 46.9% for HG and LG respectively, which did not show a significant difference between the two groups. The proportions of other unsaturated fatty acids did not show any significant differences between the two groups as well. Furthermore, US/S of the two groups did not show a significant difference.
Juiciness of HG was significantly higher than LG (p < 0.05) and overall acceptability, which synthesized each of the sensory characteristics, was higher for HG than LG (p = 0.05). As a result of the sensory evaluation on M. longissimus dorsi, which had no significant differences in WBSF, cooking loss, WHC and fatty acid composition, and which had only a significant difference in intramuscular fat, it is indicated that intramuscular fat considerably affects juiciness and overall acceptability.
Chart of fatty acid content from two different BMS scores in Japanese Black twins reported by Okumura et al 2007 and prepared by Wagyu InternationalnoneChart of sensory scores by two BMS scores from twin Japnase Black steers by Okumura prepared by Wagyu International
A report on breeding value and future improvement of Japanese beef that was held in Tōkai, Ibaraki prefecture in 2009 presented results in response to a questionnaire. Priority was given by 69.5% for Meat colour and lustre, then 28.5% for juiciness and 21.6% for texture. Abundant marbling (12.4%) was preferred over less marbling (6.4%), though 44% preferred less (subcutaneous) fat while 2.6% liked abundant fat. These results reveal that marbled beef is preferred over lean beef, but there is a higher preference for less ‘fat’. It was considered that the maximum level of fat in beef for it to be considered to be delicious is 33%. Very roughly, because of such variance within each grade, this would be around BMS 3 or above AUS-MEAT Marble Score 9.
Guidelines on the method for evaluating the taste of beef were followed for the sensory assessment by fatty acid. Only traits with levels of significance are reported. Saturated fatty acids palmitic acid C16:0 (- 0.48) and margaric acid C17:0 (-0.52) were significantly unfavourable for aroma and C17:0 (- 0.44) was significantly unfavourable for taste. Unsaturated fatty acids (+0.47) and monounsaturated fatty acids (+0.44) were favourable for aroma while saturated fatty acids (- 0.47) were significantly unfavourable for aroma. Polyunsaturated linoleic acid C18:3 (-0.43) was significantly unfavourable with a greasy taste. The trends with major fatty acids are illustrated in the bar chart below. Oleic acid (C18:1) is the most abundant fatty acid in Japanese Black from grain finishing and has a trend for favourable aroma and taste. The other monounsaturated fatty acid, palmitoleic acid C16:1 is less prolific in Japanese Black, except in finished old culled cows, but also has trends of favourable aroma and taste. Polyunsaturated fatty acids have a favourable health profile because of the higher omega-3 content, but the trend for aroma and taste is positive but weak. Linolenic acid (C18:3) is more favourable than linoleic acid (C18:2) but has the highest greasy flavour (p <0.05).
It is concluded that the most desirable fatty acid for eating quality in beef is oleic acid (C18:1).
Graph showing consumer preference for beef in JapannoneChart of sensory tests of fatty acids and beef traits in Japan
The fatty acid composition in cattle is less dependent on diet than in mono-gastric animals. However, diet does still influence the bovine fatty acid composition. Different Japanese Black sire lines have significant differences in fatty acid composition so this suggests that fatty acid composition is influenced by genetic factors. Many genes have been found to be associated to varying degrees with fatty acid composition in Japanese Black cattle.

In general, traits in cattle - such as fatty acid composition - have been considered to be polygenic (determined by many genes). Although the mechanism for adipose tissue development is extremely complicated, several genes have been identified and confirmed as being either associated with or responsible for the fatty acid composition in Japanese Black cattle. Oleic acid is the MUFA that is favourably associated with flavour. Oleic acid and MUFA are generally regarded to have a favourable health profile for human heart disease. Progeny from leading Japanese Black sires were tested for oleic acid content in Hyōgo (Kagawa). 第2鶴雪土井, son of Dai 2 Yasutsuru Doi, tested highest out of the seven. Dai 2 Yasutsuru Doi was placed fourth. He had preceded Yasufuku and was extremely popular from the quality of his meat in Japan but growth of his progeny was slow. Two of his sons were foundation exports from Japan – Fukutsuru 068 and Kitatsurukiku Doi “007”. Progeny from Fukutsuru 068 are light in weight but high in subcutaneous fat thickness and marble score (IMF%) EBV is below average. Fukutsuru is more popular in USA where he ranks in eighth place by number of registrations amongst the Foundations.
The second highest Hyōgo sire, Terunaga Doi, is father of Kitateruyasu Doi, the Westholme foundation bull also known as “003”.  He is popular for producing Fullblood 450-500 day grain finishing from the performance of his progeny and high IMF% estimated breeding values. With 3,884 registered progeny in Australia he is amongst the more popular foundation sires and this is primarily from observations of his progeny from commercial lotfeeding in Australia. Subsequently his carcase traits were substantiated when single step genomic EBVs were published. Kitateruyasu Doi is amongst the leading sires outside Japan for overall eating quality from Fullblood grain finishing.
Tanifuku Doi, fifth on the list, is sire of Foundation bull Kikutsuru Doi TF146.
The common link between Tanifuku Doi and Dai 2 Yasutsuru Doi is their mother Kikutsuru - who happens to be my favourite Japanese Black dam.
Oleic acid is tested in a fatty acid profile and genomic evaluations are under investigation.

Melting point

Melting point is another indication of eating quality because fat that melts in the mouth enhances eating pleasure. Dr Sally Lloyd of CY O’Connor ERADE Village Foundation promoted testing for melting point in Australia. Results from the Australian Branded Beef competition in 2015 included melting point (data from AWA, 2015). Melting point had an association with IMF% (R = +0.45) and there was a positive trend of IMF% with Judges’ Scores (R = + 0.35). There was no association between Melting point and Judges’ score (R = - 0.08). The lowest Melting point (28.3%) was recorded from a 5 year old pasture fed steer which had 19% IMF%.
Inoue et al, 2008 measured melting point, fatty acid composition and carcass traits in Japanese Black cattle. Genetic correlations between Melting point and each saturated fatty acid were positive, while those between melting point and each unsaturated fatty acid or the ratio of unsaturated fatty acids over saturated fatty acids were negative. Differences among the sire groups in BMS and melting point were significant (P < 0.05). The relations between BMS and melting point were independent so these results suggest that it is possible to simultaneously improve both the quantity and quality of beef fat. The genetic and phenotypic correlations between Melting point with Fatty acids are illustrated below, to the right..
The heritability of Melting point was found to be 0.41 and with demonstrated sire effects, whole genome screening should be undertaken in the Kerwee study so that EBVs can be estimated.
Branded beef competition judges' scores against marbling (IMF) % and Melting pointnoneChart of correlation of melting point with fatty acids in Japanese Black

Stearoyl-CoA desaturase and lipids

Stearoyl-CoA desaturase (SCD) was one of the early genes to be associated with fatty acid composition in beef (Taniguchi et al, 2004). The SCD gene originally was made of Effect of SCD gene on MUFA % and Melting point in IMF in Japanese Black steersthe amino acid called valine (V type) but it was then substituted through a mutation to alanine (A type). There was a positive association between MUFA content with genotype. The genotype AA showed 1.7% higher MUFA percentage than the genotype VV. However, there was a large variation in MUFA content within each genotype with considerable overlapping. There was a negative correlation between melting point of intramuscular fat with SCD genotype. There was also large variation of melting point of intramuscular fat of the raw data within each genotype.
The variation within each genotype from the trial data is illustrated below. An outlier with VV genotype had a MUFA of 72.8% which is higher than all of those that had the AA genotype. To the other extreme, an animal with the AA genotype recorded MUFA of 50.5% which is lower than all of those with VV genotypes.
The authors concluded that the SCD genotype is not the only cause of genetic variation in fatty acid composition of Japanese Black carcasses.
Another trial found that the average effects of gene substitution of the SCD type A gene on the monounsaturated fatty acid (MUFA) percentage and the melting point of intramuscular fat were approximately +1.0% and -1.0°C, respectively. However, no effect of SCD or SREBP-1 genotypes on any representative carcass traits of Japanese Black in the field population was observed (Mannen H, 2011).
Kawamura et al, 2008 carried out extensive studies on physicochemical characteristics and sensory characteristics of Japanese Black beef. Intramuscular fat melting point is significantly lower in type AA than type VA (P < 0.05), and fatty acid composition is higher in myristoleic acid (C14:1) type AA than type VA or VV (P < 0.05), In saturated fatty acid stearic acid (C18:0), a difference was found between type AA and type VA (P < 0.05). Total unsaturated fatty acid (USFA), monounsaturated fatty acid (MUFA), unsaturated degree of fatty acid (total unsaturated fatty acid / total saturated fatty acid: US / S) are all higher in AA type than in VA type (P < 0.05) but no significant differences were found with SCD genotype in subcutaneous fat.
There was no significant difference between SCD genotypes in the sensory evaluation by the tasting panel or of physiochemical characteristics except that the pressed meat juice rate was significantly higher for AA than for VA.
Chart showing fatty acid composition from SCD genotype in Japanese BlacknoneChart of melting point by SCD genotype from intramuscular and subcutaneous fat in Japanese Black
The abundance of tests that have been reported in USA shows that SCD genotypes are confined to families in the global Black Wagyu population. Foundation sires that have been tested AA in the SCD test are Fukutsuru, Kikuyasu 400, Kitateruyasu Doi, Michifuku, Sanjirou and Yasufuku Jr. Both Fukutsuru 068 and Kitateruyasu Doi are descendants of sires that were found from testing in Hyōgo in Japan to convey high oleic acid to their offspring.
Michifuku, Sanjirou and Yasufuku Jr are known to produce quality carcasses so the potential to have some added benefit from some additional lipid is a positive bonus.
The exception is Kikuyasu 400. Japanese author, Kenichi Ono, wrote that Kikuyasu 400’s sire, Kikuyasu Doi has the lowest growth rates amongst the Kikumi-Doi family. In unpublished data, Kikuysasu 400 progeny in Australia recorded the lightest induction weights after backgrounding and required 24 months on feed to reach market weight. Genomic EBVs for Kikuysasu 400 award him three traits above average – yield, eye muscle area and low birth weight - despite weighing 900kg. With his strong muscling and potential for favourable fatty acid content, Kikuyasu 400 could have a role in boutique feeding situations where a premium can be obtained to compensate for the very long feeding period required in order to obtain favourable eating quality at three years of age. Some females from combinations of Kikumi-Doi lines with Tafuku-Doi/Yasutani-Doi genetics – such as Kikutsuru who was mother to Tanifuku Doi then Dai 2 Yasutsuru plus many daughters – have made lasting contributions in Japan.
SCD was the first gene to be associated with lipid content.

Several genes have an association with lipid content

Several genes affecting fatty acid composition have been identified. Sterol regulatory element binding protein-1 (SREBP-1) regulates gene transcription (copying) activation by binding sequences that are contained in the promoters of downstream genes, including the SCD gene, to the sterol regulatory element. The intron polymorphism of SREBP-1 also affects the fatty acid composition in bovine adipose tissue.
Bovine fatty acid synthase (FASN) generates a multifunctional enzyme that regulates biosynthesis of long-chain fatty acids in mammals. FASN genotypes affected the fatty acid composition of dorsal, intramuscular and intermuscular fat in an F2 population from Japanese Black and Limousin cattle. Representative genes such as SCD and FASN have been used as DNA markers to select sires.
Although the mechanism in adipose (fat) tissue is extremely complicated, several additional genes have been identified and confirmed as being either associated with or are responsible for the fatty acid composition in Japanese Black cattle. 
The following genes were reported to affect fatty acid composition: adipocytes fatty acid binding protein (FABP4), liver X receptor α (LXRα), elongation of very-long-chain fatty acid 5 (ELOVL5), fatty acid desaturase 2 (FADS2), acetyl-CoA carboxylase-α (ACACA), and urotensin 2 receptor.
The single and epistatic (joint) effects of four genes (FASN, SCD, SREBP1, and GH) with a total of five variations were evaluated on the fatty acid composition of the longissimus thoracis muscle and carcass and meat quality traits in 480 Japanese Black cattle.
The genotypic and allelic frequencies for the five polymorphic genetic markers in the four genes are shown in the table below. The major alleles of each marker were as follows: allele TW in FASN, allele A in SCD, allele V in GHL127V, and allele T in GHT172M. The allele frequencies for FASN were substantially biased toward the allele TW and there were only four animals with the genotype AR/ AR. There was little bias in the allele frequencies for SREBP1.


Genotype and genotypic frequency

Allelic frequency



































































Significant single effects of FASN, SCD, and GHL127V polymorphisms on the fatty acid composition were detected.  Combined response to the single effects on each fatty acid ranged between 5 and 30% of the total. When the genotypes of all three markers (FASN, SCD, and GHL127V) were substituted from the lesser effect allele to the greater effect allele, the proportion of C18:1 (oleic acid) increased by 4.46%. Polymorphisms in 2 fatty acid synthesis genes (FASN and SCD) independently influenced fatty acid composition in the longissimus thoracis muscle.
% variation in fatty acid composition from independent gene effects in IMF in Japanese Black Wagyunone% variation in carcass traits from independent gene effects in Japanese Black Wagyu
In a previous study, significant effects of the FASN genotype were reported on the lipids C14:0, C14:1, C16:0, C16:1 and C18:1 content of the trapezius muscle intramuscular fat in Japanese Black populations. In the present study, the same effect of the FASN marker was detected for the intramuscular fat of the longissimus thoracis muscle.
In another study, the group with genotype LL for the GH marker had a greater percentage of C14:1 and C16:1 and a reduced percentage of C18:0 in longissimus thoracis muscle lipid, compared with the group with genotype VV. In this study, similar effects were detected at the same mutation site.

Single nucleotide polymorphism and carcass traits

Moving away from fatty acids, endothelial differentiation sphingolipid G-protein-coupled receptor 1 (EDG1) (Sukegawa et al, 2010) gene was associated with the BMS level in a Japanese Black beef cattle population in Oita prefecture. The G allele is associated with a high level of BMS. This association was investigated in other prefectures. 
The effect of the genotype on the BMS level was not statistically significant in the Kagoshima prefecture population (P > 0.05) in which the predominant breeding objective has been for carcase weight. BMS has been historically selected for in the Miyazaki and Nagasaki prefectures so many quantitative trait loci for the BMS are thought to have been fixed in those populations. The carcase weight, rib loin area and fib fat thickness values were significantly higher in the GG homozygotes than in the AA homozygotes, and the values in the heterozygotes were intermediate between those in the 2 homozygotes. Thus, just like its effect on the BMS, the effects of the G allele on carcass traits other than the BMS, if any, seemed to be favourable rather than deleterious.

Growth hormone and performance

Another gene that has been found to have important roles in regulating animal growth and production is the growth hormone (GH) gene that has been extensively investigated in Japanese Black cattle (Kagawa). The frequency of the B allele was higher (0.421) than that of A (0.269) and C (0.311). High carcass weight (p < 0.05) and low beef marbling (p < 0.01) were associated with allele A, whereas beef marbling was increased by allele C (P < 0.05).
The following year, other workers found that allele A gave greater rib thickness and lower melting point of fat while allele B gave higher oleic acid fatty acid % (C18:1) (P < 0.05). Allele C gave higher oleic acid C18:1, monounsaturated fatty acid (MUFA), unsaturated fatty acid (USFA) percentages (P < 0.05). It also gave lower saturated fatty acid (SFA) percentages, higher MUFA/SFA and USFA/SFA ratios, and lower melting point (P < 0.05).
The distribution of GH genes is the result of selection pressure that has applied over the past and is directly related to prefecture and Wagyu strain. Nakadoi-kei strain (called Tajima outside Japan) comprises descendants from Nakadoi, and subsequently through Tajiri, and predominantly has B and C bGH alleles. Fujiyoshi strains and those from Okayama and Shimane prefectures predominantly have A and C alleles. The other major strain that is present amongst the exports from Japan is the Kedaka line from Tottori and Kedaka which is predominantly A. The Iwate-kei from Hiroshima is also mainly A. The foundation animals which form the basis of the Wagyu population outside Japan combine pairs of A, B and C alleles and are largely influenced by original family line or prefecture of origin.
Summary of the effects that each GH allele has on major carcase traits in Japanese Black:

Carcase trait

GH allele




Carcase weight




Marbling (IMF%)




Rib loin area




The effects of A and C allele are antagonistic between Carcase weight with both marbling (IMF%) and rib loin area while the B allele is intermediate. The implications from selection solely by GH allele will have a significant influence on the genotype of a herd or population.
Mr Shogo Takeda advocated the Fullblood Rotation Program when he became concerned that too much selection pressure was being applied towards marbling at the expense of frame size when Wagyu were introduced from Japan to the Americas and Australia. The principle is to cross cows from Frame sires to Marbling sires. Cows from Marbling sires are joined to Frame sires. Classification is based on prefectural content (also called 16/16). More information is detailed on the Wagyu Fullblood Rotation program that has been posted on this site.
Classification for Genetics reports by Wagyu International is primarily from a database compiled from copies of registrations in Japan as published in Kenichi Ono books. The registration is completed in the prefecture where the sire has completed the performance test so it can differ from prefecture of origin. There are more than 28 prefecture names in the Wagyu International database but only seven are reported and the remainder are grouped together as ‘Other’. Usually there is less than 5% in the ‘Other’ group. Dai 7 Itozakura who was born in Shimane from an Okayama sire is considered to be the founder of the modern Itozakura group.
There is some variation in methodology for classification used by different parties.
Whichever system of classification for Fullblood Rotation is used is not of much importance, but consistent use within one is very important to ensure that there is a constant rotation from growth to carcass, and carcass to growth perpetually for sustainability of the Fullblood seedstock herd. A deviation from the Wagyu Fullblood Rotation – such as selecting on GH results from Exon 5 tests – will have the same consequence that resulted from selecting too heavily on Tajima content. The B and C alleles in Tajima are more frequent in B and D sires in the Wagyu Fullblood Rotation. The A and C alleles from Fujiyoshi/Itozakura and Okayama are more prevalent in the A group. The A allele is highest from Kedaka and Hiroshima strains so is the major component in C group.

Whole genome sequencing

Accurate phonotypic (physical or chemical) measurements are taken and compared with the thousands of SNPs during a genomic-wide association study (GWAS). In this way, associations are made between SNPs and complex traits. Heritabilities are increasing from trials with 770k SNPs compared to those previously from low density SNP arrays.
The composition of fatty acids was assessed in Japanese Black cattle (Onogi et al, 2015). Genotyped animals were validated and the prediction accuracy was higher with ssGBLUP than with best linear unbiased prediction (BLUP).
A genome-wide association study (Sasago et al, 2016) and candidate gene analysis was carried out with Japanese Black cattle to evaluate the effectiveness of the GWAS for carcass weight (CW) and fatty acid composition and to detect novel candidate regions affecting non-CW carcass traits, chemical composition and sugar. In addition, the association of the candidate genes previously detected in CW and fatty acid composition were evaluated with other economically important traits. The significant regions with the candidate genes were detected for CW and fatty acid composition, and these results showed that a significant region was detectable. The novel candidate regions were detected for crude protein and for fructose. CW-related genes associated with the rib-eye area and fatty acid composition were identified, and fatty acid-related genes had no relationship with other traits. Moreover, the favourable allele of CW-related genes had an unfavourable effect on fatty acid composition.
This is an active area of research presently.


Geneticist Don Nichol was the driver in Australia for GeneSTAR® Marbling Nichol 2001 which was launched in July 2000 with joint input from Beef CRC as the first DNA marker test for commercial use by Australian beef producers. 
An association was found between number of tenderness markers and the measured tenderness (Nichol, 2008).  Although  statistically  significant,  the  total  amount  of phenotypic  variation  in  tenderness  accounted  for  by the GeneSTAR tenderness markers was only around 4% in  temperate  breeds  and  6%  in  tropical  breeds. While encouraging, it meant many more markers were required in both groups of breeds to account for a sizeable percentage of variation.
Nicol’s evaluation for marbling did not find statistically significant (P>0.05) marker effect as either individual markers or as increasing ‘stars’. Marbling markers were not consistent for IMF, MSA marble score or AUS-MEAT marble score in any of the populations tested. 
Net feed intake (NFI)is a measure of how much an animal eats relative to an expected amount for its weight and growth rate. The effect of increasing number of ‘stars’ was statistically significant for NFI (P<0.05) in the CRC temperate breed population, but not statistically significant in any other population. 
GeneSTAR MVP using 56 markers replaced the initial 12 marker test. Pfizer claimed reliability values of 30, 26 and 39 percent for feed efficiency, marbling and tenderness, respectively in their promotions. However, marbling is the key focus for Wagyu producers so GeneSTAR was largely abandoned by the Wagyu industry in Australia.
Pfizer (later to be called Zoetis) persevered with other breeds and the 50K SNP test is incorporated in several countries into a BLUP analysis. The Zoetis i20K is a lower density (20,000SNP) with a lower cost version of the Zoetis HD50K, but with comparable accuracy.
A comprehensive array of 22 traits are tested by the Zoetis i50K and HD500K products and 14 traits are incorporated into Angus BREEDPLAN.
Trends have recently been found of a positive association between marbling MVPs from published GeneSTAR results in a sales catalogue for Black Wagyu with ssgBLUP marble score EBVs. This indicates that some markers are presently common to both.

Constraints from limitations of visual grading of Marbling (IMF%)

Digital analysis of carcasses revealed the variability in marbling (IMF) % from grading in both Japan and Australian plants. In almost every case, the IMF% exceeds the minimum that is stipulated for each grade, but the wide range of IMF% within each grade is likely to be masking potential genetic relationships. Large data sets would be required to overcome this overlapping of the same IMF% across many marble grades and may be the major factor behind the need for at least 20 Fullblood and 80 F1 progeny per sire. The weight of a carcass is accurately measured at time of processing and EMA/REA estimates, despite being manual, are reasonably consistent. The range in IMF%, and average for each marbling grade in Australia and Japan from early digital assessments is illustrated below (data from Grose J, 2011):
Chart showing variation of Marbling (IMF) % within each marble grade of BMS in Japan and Marble Score by AUS-MEAT in Australia
Days on feed and efficiency when finishing
The conundrum in the feedlot is to identify those Wagyu animals that are heavier than 550 kg that are laying marbling for which there is financial gain and those that are adding more backfat with an uneconomic conversion. Those that have grown on a controlled program through weaning and backgrounding will have the benefit of balanced muscle on a full frame. High Marble score EBVs for terminal sires for the feedlot are essential, and Scott de Bruin of Chart showing gross margin variance with rump fat estimated breeding value from preliminary feed efficiency trial at Kerwee feedlot with Black WagyuMayura Wagyu has stated that by using EMA EBVs is his selection, he has earned an additional $550 per carcass.
On the other hand, high subcutaneous fat thickness (Rump fat EBV) will have a tendency to lay down backfat at an earlier age and continue during the feeding operation. Even during Yasufuku’s day, his advantage in increasing marbling without subcutaneous fat deposition was noted.
Wagyu Fullblood carcass data from a producer in Victoria were analysed.  Dressing percentage was found to be negatively associated with rib fat thickness (R = -0.5). This aligns with the association between waste and subcutaneous fat thickness in Japan NARO 2008. 
The relationship between backfat thickness and feeding efficiency was evaluated using preliminary data that was shared from the ongoing Feed Efficiency Test at Kerwee Feedlot AWA conference 2017. Performance and net feed intake was recorded for progeny. Not all sires were identified in charts, but those that were, were evaluated against Rump fat EBVs. Results were shown of Feed Cost variances, but the association between Gross Margin variance with Rump fat EBV is charted alongside.
The strongest association with Gross Margin was negative (R = – 0.93) with Rump fat EBV of sire, then second, but positive, was Marble score (R = + 0.54).
From such small numbers, these effects may prove to be speculative so the final report is eagerly anticipated. It is expected that consistent and moderate growth rate during backgrounding will ensure good conformation on feedlot entry, then expression of carcass traits and eating quality from efficient conversion during finishing are required to combine for optimum return.
Many independent components determine the efficiency of finishing Wagyu and they are in effect during different phases. Genetics has a considerable influence and environmental factors would affect different cohorts. However a genomic-wide association study in a controlled situation could provide a valuable $Index or EBVs for efficient Wagyu production.

How many progeny are needed to give an indication of breeding merit of carcass traits?

Breeding decisions will determine the genetic potential of the eating quality. A detailed report has been written on the number of progeny that are required for on-farm evaluation.
For instance, a minimum of 50 Fullblood carcasses from a sire are required for reliability.
Between 200 and 12,000 F1 progeny from 12 World K’s sires were finished for 540 days. Despite the large number of progeny, there were some outliers when AUS-MEAT Marble Score grade was evaluated against genomic Marble Score EBV, and when daily gain over 540 days was compared with growth EBVs.
An analysis of accuracy of Marbling EPD from Wagyu cross shows that 650 F1 carcasses that are processed using Bolt analysis are required for 75% accuracy:
Chart showing accuracy of Marbling EPDs from Washington State 2017

60% accuracy should be obtained from:
Genomic EBVs, or
BLUP analysis from 20 Fullblood progeny, or
40 Fullblood progeny, or
BLUP/Bolt analysis from 150 F1 progeny.

The target is 75% accuracy, and this will be secured in most cases from:
10 carcass progeny in combination with genomic EBVs.
Alternatively, BLUP/Bolt analysis from 650 F1 progeny will give the same result.

The importance of recognizing the 50% contribution in DNA from the dam should never be overlooked.

Overview of genetic contribution to eating quality

The Australians have considered the influence from the SCD gene on eating quality to be insufficient to merit testing for it except animals that have a potential for export. No single test is available yet that determines the composition of the major desirable fatty acids but whole genome testing might provide the solution.
Trials on Net Feed Intake are ongoing at Kerwee Feedlot and intake breeding values should be generated after sufficient data has been generated. This will be a valuable complement to BREEDPLAN EBVs and the only gap remaining will be eating quality. Oleic acid and melting point have been used recently to describe eating quality in Japanese Black in Japan (Ono, 2017). If they have been recorded in carcasses from Kerwee then it is only a matter of time before those EBVs should become available. However, if the work has to commence now, it is suggested that a full fatty acid profile be obtained so that aspects of human health can also be addressed. The full fatty acid profile should be recorded so that the omega-6:omega-3 ratio from Wagyu can be confirmed.
The 500K SNP is a single test that provides a comprehensive breeding evaluation for multiple traits from single step gBLUP in Australia.
Progress had been rapid since digital imaging improved the accuracy of phenotypic measurements. Prof Rob Banks has stated that the accuracy from scanned data for Wagyu is only 30%. Caution should be applied when only scanned progeny have been analysed for Marble score EBVs.
Similarly, unless progeny have been raised together, they should not be submitted as cohorts because this will also have an adverse impact on how the data will be analysed.
The genomic EBVs can be obtained early in life and the best will require carcass data from progeny for incorporation into ssgBLUP analysis. Failing that, a minimum of 40 Fullblood progeny carcasses are needed from each candidate sire to be “proven” as trends only become evident from 20. Otherwise, 80 F1 progeny carcasses are required from crosses. The AWA tour to the Nick & Vicky Sher’s property in Victoria in May 2019 was told how they evaluate their own candidate sires from F1 progeny. During the farm tour, I asked Leigh Bradbury how many progeny results are required from each sire to get an evaluation and he answered 70. Fewer progeny would be sufficient when there is consistency amongst all of the dams. Unless 70 to 80 crossbred progeny have been obtained from any parent, any carcass claims that are made when marketing can only be considered to be speculative.
The best illustration of the influence from a dam is to compare Michifuku with his half-brother Haruki II as they both have the same sire Monjirō. Michifuku is a leader for carcass traits and Haruki II is a leader for maternal traits. Michifuku is +50% wi CI and -50% wiMI while Haruki II is -50% wi CI and +50% wi MI. It is not possible to be more extreme yet they both share 25% of each other’s DNA! The EBVs are illustrated below:
Chart of estimated breeding values and Wagyu International Indicators for Michifuku a leading foundation Wagyu bullnoneChart of estimated breeding values of Haruki II foundation Wagyu bull
This illustrates why many progeny (a minimum of at least 20 Fullblood) are required before an average will give a representative indication of one sire and why a BLUP analysis is required to eliminate the influence of the dam in progeny tests. Brothers from the same parents share 50% of each other’s DNA, whilst half-brothers in a progeny test, share only 25% of their DNA. The long overdue accurate measurement of marbling % that has been provided by digital imaging and, together with single step genomic BLUP analysis from BREEDPLAN, and the introduction of Marbling Fineness EBV, rapid progress in identifying animals with superior breeding merit is taking place in Australia. Progeny that has EBVs that are 30 to 50% better than their parents are now replacing the Foundation generation. Recognition has come from sales this year when not only has the highest price for a beef female been broken by two Wagyu females, but the highest price for a dairy cow, which was higher, was also broken by a 17 month old Wagyu heifer to an international buyer.
However, for those who cannot record their carcasses for BLUP analysis, the following information is provided. Breeding merit for carcass traits for 45 sires that are either leading or second generation Foundation sires is summarised in Figures 20 to 22. EBVs have been ranked against breed midpoint and the more favourable EBVs are above the 0% (Midpoint line). The more important traits are towards to the left - yellow for Marble score, white for Marble fineness and light green for EMA. 'FA content' is a combination of oleic acid content results from Hyogo and the SCD gene and on the far right as a dark blue bar.
Chart of breeding merit for carcass traits of the most influential foundation Black Wagyu siresnoneChart of breeding merit of carcass traits of some Black Wagyu foundation siresnoneChart of breeding merit of carcass traits of 1976 and second generation Black Wagyu sires
The average for all traits in these charts from the leading foundation sires and the second generation appears to be below midpoint. This is to be expected due to improvement in breeding merit that would result each progressive generation from effective breeding selection.
Photo of Wagyu sire YasufukuhisaThe Wagyu breed is usually finished with adequate marbling in order to receive a premium in the market and the quality of the beef is assured – especially when fineness of marbling is given second priority after IMF%. The third trait to be incorporated in selection is eye muscle area. Tenderness is rarely a limiting factor so there is no economic merit to select for the tenderness gene in the Wagyu breed when they are raised under conventional commercial conditions.
It is intriguing to read about a recent super-sire Yasufukuhisa in Japan who was born in 2001 and passed away in 2016. He is considered to have completed the last era in Japanese Black breeding and 30 progeny had an average BMS of 10.1. His sire is the son of Yasufuku who produced breeding values that were higher than his famous father. On the maternal side one grandsire is Monjirō (sire of Michifuku) and Harumi (Kedaka) comes in on the other side of the maternal line. His only drawback was low oleic acid content and elevated melting point. REA was 74.2 cm2 and carcass weight averaged 500.9kg from an average age of 28.1 months of age. Other superior sires in Japan have been combinations of at least two leading Tajima sires and very often Dai 20 Shigeru is in the background or Dai 7 Itozakura to a lesser extent. The similarities are uncanny when looking through auction results in Australia where the most successful Foundation ancestors are the next generation from the leading Japanese sires from the 1970-80s.
In both countries, genomic BLUP is a powerful tool for breeders and producers. The challenge is to select Wagyu genetics to provide the best eating Wagyu more efficiently at a younger age.
There is a negative association between Marble Score EBV and Carcass Weight EBV (r2 = - 0.35). If selection is only for either of these traits, the performance of the other is going to decline progressivley. By selecting for animals that are both average for Marble Score and Carcass Weight, the overall carcass weight and marbling score can improve ina herd.
Chart showing association ebtween AUS-MEAT Marble Score and Carcass Weight EBV in Australian BREEDPLAN



Temperament is the way in which an individual animal reacts to an unfamiliar or challenging situation. Temperament of an individual animal is a result of both its inherent temperament and its environment, including handling and training.
Research has found favourable genetic and phenotypic relationships between temperament and meat quality, feedlot performance, ease of transport and some reproductive traits indicating that selection to improve temperament will also result in genetic improvements in these traits.
Animals with poor temperament are more likely to produce progeny whose beef is of unacceptable eating quality. This is because stress depletes glycogen in nervous animals prior to slaughter, potentially resulting in dark-cutting meat or reducing the ability of the beef to age effectively post-mortem. Measurements taken on Bos indicus and their composites showed that flight time had a strong favourable genetic correlation with MSA eating meat quality score and MSA tenderness score. Favourable genetic and phenotypic correlations were also found between flight time and steer striploin tenderness across the breed spectrum that had been finished in feedlots.
Research has also shown that tropically adapted cattle with better temperament lose less weight during long distance transport, plus regain lost weight more rapidly post-transport. Three groups of steers were transported 1,365km on a 4–5 day trip. Steers with the fastest flight times lost 5% more weight than steers with slowest flight times. Flight time measures were also found to be useful predictors of how well groups of animals fared during a long distance journey.
Animals across tropically adapted and British breeds with good temperament have higher weight gains in feedlots. In Brahman derived breeds, steers with the best temperament grew 0.38 kg/day more than steers with the worst temperament. In another experiment it was demonstrated that feedlot cattle with poor temperament incurred more health issues.
Whereas Wagyu as a breed is not considered to have issues with temperament, when they are not in regular contact they may become quite flighty during backgrounding. With automated feeding systems they may became wary of human contact. Training may improve an animal’s reactions in a familiar situation so regular human contact during lotfeeding may result in less stress during handling. This may have an influence on weight gain during finishing. Whereas regular contact may have less influence over an animal’s inherent reaction in unfamiliar environments – such as during transport and at slaughter – the benefits on-farm have been demonstrated. Whilst regular contact may not always keep animals calm during processing, any reduction in the depletion of glycogen levels from stress will improve grading and eating quality.

Importance of nutrition for Wagyu eating quality

The Wagyu breeds 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 other beef breeds or in milk 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.

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.

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%. However, it has been acknowledged that shortening the fattening period will have an impact on carcass weight and meat quality.

Calves in Japan are typically sold to the fattening industry between 8 and 10 months of age depending on strain/prefecture.  Although there are differences of sex and strain of Black Wagyu, the weight for age at the calf markets is a useful indication of finishing potential. 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 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 taken on a different perspective. The numerous results have been reviewed by Wagyu International and any findings that have implications for either pasture or grain finishing of Wagyu in the global arena are applied. The effect of ADG and the time to reach the same end-point on marbling (IMF%) is illustrated below:

Chart showing marbling IMF% versus ADG and age of processing Wagyu

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. 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 Pathways during carbohydrate fermentation in the rumenthe 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 CO2 which 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 highest for propionate, intermediate for butyrate, and lowest 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.

The acetate:propionate ratio is important but there is a negative trend between NDF and IMF%. Research data from fattening trials in Japan have been reviewed by Wagyu International is continually monitoring progress in Japan and applying it through collaborations with producers in the northern and southern hemispheres. As always, the economics and end-points are different in every enterprise. Determination of the desired eating quality and carcass size will enable Wagyu International to recommend the growth profile and feeding program that will be based on local resources and feed components.

Many producers are content to follow their neighbours. Those that want excellence contact Wagyu International.


Akaushi. See Japanese Brown.
American Wagyu. Four bulls were imported from Japan to USA in 1976. They were crossed over local breeds and the fourth generation were classed as Purebreds with 93.75% Wagyu content. During the 1990s both in-calf heifers and bulls were imported from Japan, so 100% Wagyu (Fullblood) were bred. The minimum content that is permitted for beef to be labelled Wagyu in USA is 46%.
AUS-MEAT Eye Muscle Area (EMA). Eye Muscle Area is the area of the surface of the
M. longissimus dorsi at the ribbing site and is calculated in square centimetres. Eye Muscle Area
may be measured at the 10th, 11th, 12th or 13th rib.
AUS-MEAT Marble Score (MS). The AUS-MEAT marbling scores range from 0 (nil) to 9 (abundant) and are assessed based upon the amount of marbling present in the eye muscle and is assessed from the 5th to 13th rib on the carcase, depending on market. The grader checks from marbling chips before a grade is awarded. The IMF% against Marble Score grade for the first 550 Wagyu carcases that were digitally recorded in Australia is shown in jade colour, while white circles show the minimum IMF% for each grade in the chart to the left, below (data from Grose J, 2011). The chart next to it, on the right, illustrates the minimum IMF% for each marbling grade in Japan, Australia and USA:
Chart of IMF% for each AUS-MEAT Marble Score in AustralianoneChart of Marbling (IMF) % by BMS in Japan, by Marble Score in AUS-MEAT in Australia and in Prime, Choice and Select from USDA in USA on Wagyu International
The IMF% by Marble Score in Australia is approximately half the IMF% for the same BMS in Japan. For example, Marble Score 4 in Australia has an average IMF of 15%, while BMS 4 in Japan has an average IMF that is above 40% Grose, 2011. Therefore, it is misleading when marbling scores in Australia are referred to as “BMS” in auction catalogues or in sales promotions when they are really AUS-MEAT “MS”.
Beef Marbling Standard (BMS). Silicone resin models are used by graders for beef marbling to standardize the degree of marbling in different processing plants across Japan. The score is from 1 to 12 and there is minimum intramuscular fat percentage content for each score from 3. Score 1 is given when marbling is absent, and 2 is awarded when the minimum standard of 3 is not reached.
Australian Wagyu. Purebred embryos were imported from USA to Australia, but most Australian breeders build their herds with 100% content when the second wave of imports arrived in USA in the 1990s as females were included. The minimum content that is permitted for beef to be labelled Wagyu in Australia is 50%. 100% Wagyu content is called Fullblood Wagyu.
Bayesian inference (BayesB/R) is a method of statistical inference in which Bayes' theorem is used to update the probability for a hypothesis as more evidence or information becomes available. Bayes' theorem describes the probability of an event, based on prior knowledge of conditions that might be related to the event.
Best Linear Unbiased Prediction (BLUP) is the technology that incorporates multi-trait   analysis   procedures to  produce  estimates  of  breeding  values  (EBVs) for  recorded cattle across a range of important production traits.  Fixed effects of environment and genetics on observed phenotypic values are estimated simultaneously using BLUP and, therefore, genetic differences between herds are accounted for.
Black Wagyu. Numerous export consignments of Japanese Black were exported from Japan to USA. After quarantine periods were completed a number of them were exported to Canada and Australia while many remained in Australia. The Tajima, Itozakura, Kedaka and some Fujiyoshi are the major strains. Wagyu populations are raised globally in at least 35 countries.
BMS. See Beef Marbling Standard.
Cohort. A cohort or contemporary group consists of animals raised under the same management conditions.
English. Spelling has mainly been Australian English which resembles the original British English and differs from American English.
Estimated Breeding Value (EBV) is the genetic merit for each trait. EBVs are expressed as the difference between an individual animal’s genetics and the genetic base to which the animal is compared.  EBVs are reported in the units in which the measurements are taken. On average, half of the EBV will be passed on to the animal’s progeny because the other half will pass from the other parent.
Expected Progeny Differences (EPDs) provide estimates of the genetic value of an animal as a parent. Specifically, differences in EPDs between two individuals of the same breed predict differences in performance between their future offspring when each is mated to animals of the same average genetic merit.Photo showing plastic grid over rib loin to measure eye muscle area in AUS-MEAT grading
Eye muscle area (EMA) or REA in Japan. Eye Muscle Area is the area of the surface of the M.longissimus dorsi at the ribbing site and is calculated in square centimetres. EMA may be measured at the 10th, 11th, 12th or 13th rib. EMA is measured manually using a plastic grid (photo to the right).
Genomic Best Linear Unbiased Prediction (GBLUP or gBLUP) is a method that utilizes genomic relationships to estimate the genetic merit of an individual. For this purpose, a genomic relationship matrix is used, estimated from DNA marker information.
Japanese Black. There are four beef cattle breeds In Japan – Japanese Black, Japanese Brown, Japanese Shorthorn and Japanese Polled. The high levels marbling in beef produced by Japanese Black cattle has led to this breed comprising the greatest share of Japan’s Wagyu cattle population (Gotoh, 2018). Each prefecture is responsible for the beef husbandry in its jurisdiction so distinct strains have evolved. Tajima in Hyogo originated from Naka-doi line and Kumanami-line, the Fujiyoshi-line from Shimane and Kedaka-kei and Eikō-line from Tottori and Kagoshima. Properties of the various strains are very distinct.
Japanese Brown. The Japanese Brown is the second most common domestic beef breed in Japan despite a reduction from 22% to 4% of the Wagyu population. It is comprised of two isolated sub‐breeds, Kumamoto and Kōchi, each possessing a different gene pool. Simmental and Korean Hanwoo were crossed with native cattle in Kumamoto and Kochi, and Devon were crossed in Kumamoto before the Japanese Brown breed evolved. The Japanese Brown breed is also called Akaushi in Japan.
Metabolisable Energy (ME) is an estimate of the energy available to an animal from digestion of a feed material, expressed in units of mega Joules per kilogram of feed (MJ/kgDM) or mega calories (Mcal/kgDM). Feed materials are comprised of a number of components (fats, proteins, carbohydrates etc), each of which are potentially metabolisable by an animal and contribute to the energy content of the feed. These components do not all contribute equally (for instance fats have higher energy content than proteins) and the concept of ME has been developed to account for these differences.
MSA Marble Score. MSA marbling scores are used to provide a finer scale than the AUS-MEAT scores.  It is assessed based upon amount as well as distribution of the marbling within the eye muscle.  Each MSA marbling score is divided into tenths for grading, creating a score range from 100 to 1,190 in increments of 10.
Net Energy (NE) for maintenance (NEm) and gain (NEg) are used to formulate diets for growing and finishing cattle. These energy values are more useful than TDN, because they allow more accurate prediction of the amount of energy used for maintenance and gain purposes. NEm of a feed measures the ability of the feed to meet the energy requirement for maintenance. NEg of a feed measures the ability of the feed to meet the energy requirements for gain. Energy needs for maintenance must be met first before the animal can use any energy for growth (gain). Once energy needs for maintenance are met, then the remaining energy in the diet can go towards gain. The reason that feeds have two different NE composition values, one for maintenance and one for gain, is that feed energy is used more efficiently for maintenance than for gain. Therefore, NEm values are always higher for a feed than NEg values.
P8 fat thickness. Fat depths may be measured manually using a cut and measure knife or electronically at the P8 site using a Hennessey Grading probe. The P8 site for AUS-MEAT grading is the point of intersection of a line from the dorsal tuberosity of the tripartite tuber ischii parallel with the chine, and a line at 90o to the sawn chine centred on the crest of the spinous process of the third sacral vertebrae. Excess or deficiency of subcutaneous fat is undesirable. Some processors of Wagyu impose a penalty for fat depth lighter than 12mm and it is heavier when less than 6mm at P8 site. A penalty applies for depth exceeding 31mm and it is heaviest for P8 fat thickness exceeding 41mm.
Site for measuring P8 fat thickness for AUS-MEAT gradingP8 fat thickness noneLocation of measurement of Rib Fat Thickness for AUS-MEAT grading in AustraliaRib fat thickness

Pedigree BLUP (PBLUP). See Best Linear Unbiased Prediction (BLUP).
Predicted Breeding Value (PBV) is the genetic merit for each trait and comparisons are made within prefectures. In Japanese literature, both PBV and EBV have been translated. See Estimated Breeding Value.
Red Wagyu. Japanese Brown cattle that were exported from Japan are either called Red Wagyu or Akuishi. They were only selected from the Kumamoto strain of Japanese Brown so there is no Kochi strain Japanese Brown outside Japan. Red Wagyu have never exceeded 4% of the Wagyu population in Australia but they have a stronger following in USA, the southern Americas, and they were fashionable for a while in South Africa.
Rib fat thickness. Rib fat is the measurement of the thickness of subcutaneous fat measured in millimetres at the specified rib. Rib fat is used in MSA grading as both a minimum requirement for grading and as a prediction input. The 3 mm minimum standard aims at reducing temperature variation through the carcase muscles during chilling. A small eating quality improvement also occurs as rib fat increases from 3 mm –18 mm and this is more significant in breeds that do not exhibit much marbling. Accordingly, in Japan, subcutaneous fat thickness has a negative effect on yield estimate score.
Subcutaneous fat thickness. Rib fat thickness is the measured depth of subcutaneous fat over the quartered rib site between the 5th and 13th ribs. Rib fat thickness may vary between sites and typically increases towards the head (5th rib). Rib fat is a better indicator of yield than the P8 site. It is measured when the carcase is chilled and quartered, as opposed to P8 fat being measured on the hot carcase on the slaughter floor.
USDA beef marbling grades. Prime beef is produced from young, well-fed beef cattle. It has slightly abundant to moderate marbling. Choice beef is high quality, but has less marbling than Prime. It has at least a small amount of marbling, and can be modest or medium. Select beef is very uniform in quality and normally leaner than the higher grades. It is fairly tender, but because it has less marbling, it may lack some of the juiciness and flavour of the higher grades. It has at least a Slight amount of marbling.

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小野健一 日本名牛百選IV
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Date of posting: 5th November, 2019

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