Health benefits and flavour advantages from Wagyu beef
Wagyu beef is so superior in eating quality that it has been excluded from competing directly with other beef breeds during the premier beef tasting competition in Brisbane since 2012. This enables other breeds to win some silverware then the winner of the Wagyu class and the winner of the non-Wagyu class compete in the Grand Final. The supreme flavour in Wagyu comes from high levels of marbling which is intramuscular fat that is spread throughout the beef. Fine meat fibres also improve the tasting experience from the soft texture. Pure Wagyu just melts in the mouth to give the ultimate eating sensation.
Wagyu is unique as its origins are from the fourth Aurochs (T4) in North East Asia some four to five thousand years ago. The role of the traditional Japanese cattle as draught animals for almost 
two thousand years may also have contributed through selection to increase the amount of fat in muscles that was the energy source. There was a short period of crossbreeding which was introduced to increase the body size and milk yield of the traditional cattle across Japan from 1868. Several distinct breeds were developed in distinct districts but the most popular two that remain are the Japanese Black and Japanese Brown. The Hanwoo breed in Korea has similar qualities to Wagyu owing to the common source and Hanwoo genetics were introduced in the south to Japanese Brown just over a hundred years ago. Wagyu that were exported from Japan are called Black Wagyu or Red Wagyu (Akaushi) depending on their source.
For beef to have an acceptable flavour to the Western palate, a minimum fat content of 30mg/kg (3%) is required. In Japan, the lowest grade for Wagyu beef is BMS 3 and this is awarded when 
intramuscular fat is just above 20%. Marbling below this content is graded BMS 2, and the absence of marbling is graded BMS 1. The highest grade is BMS 12 for 57% IMF. In Australia, marbling is graded on the AUS-MEAT score from 1 to 9 and beef which exceeds 20% IMF is awarded 9+. About a third of grain finished pure Wagyu in Australia is graded 9 or above so beyond the maximum AUS-MEAT and MSA grading. IMF% is measured to improve the heritablity of marbling and it is not unusual to find IMF that exceeds 50% - especially in the Branded Beef competition.
The best eating quality from the slower growing Wagyu breed takes a long time so a premium price is required. The demand in the market is not fully satisfied from the production of pure 100% Wagyu (Fullblood) so most Wagyu beef that is produced in Australia is 50% Wagyu content. The lower fat content of between 10 to 15% IMF that comes from cross-bred Wagyu suits the palate of many consumers and is also more affordable. Most Wagyu that is sold in Australia is F1 or 50% Wagyu with an average AUS-MEAT marble score of 5.
Wagyu have the ability to keep depositing intramuscular fat over three yearsof age or beyond whereas all other breeds plateau at a younger age and weight. The fats that are converted to marbling are healthier for the heart and they are very high in Wagyu beef.
After grain finishing, Wagyu fat usually contains about 50% monounsaturated fat (MUFA) which has a more favourable association with heart disease because beef patties containing MUFA have been found to lower cholesterol when beef patties containing saturated faty acid fat (SFA), had the oppositie effect. The MUFA with the highest abundance in Wagyu is oleic acid, and oleic acid is the major fatty acid in olive oil - hence the favourable cholesterol profile from Wagyu beef. It is only in old cows that a higher proprortion of another MUFA - palmitoleic acid - that may be at higher levels than oleic acid.
The composition of fatty acids varies according to location in the Wagyu carcass. MUFA is higher in subcutaneous fat in Wagyu than in the intramuscular fat or marbling. The distribution is illustrated in the chart above to the left.
Omega-3 and omega-6 fatty acids have implications in disease and their ratio can be influenced by the feed but they are generally higher in Wagyu beef than in many other breeds. A higher omega-6 to omega-3 ratio is considered to be unhealthy and omega-6 is higher in grains so is usually higher in high grain ration feeding. Omega-3 is higher with pasture feeding but some flavours have an adverse influence on beef flavour. The ratio between omega-3 and omerga-6 has different implications to health and flavour of beef.
Some tasting studies give an indication that some fatty acids have a favourable effect on flavour, while otrhers have an undesirable influence. Oleic acid, that is more abundant in Wagyu than in any other cattle breed is one that has the highest positive contributiuon to eating quality and lines that are known to carry it are recommended for breeding. A table showing fatty acids that are reported to have the strongest influence is shown to the right.
Most of the flavour from beef comes from MUFA and higher quality Wagyu "melts in the mouth". This is because the fatty acids have a low melting point. Some Wagyu beef have a melting point that is below room temperature and they give the very best in eating enjoyment. Matsusaka beef in Japan has been recorded to have a melting point below 20oC. Some recordings that have been made of Wagyu in Australia are shown in the chart below.
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