Key Black Wagyu Bloodlines

Introduction
  - Tsuru vs Modern Lines
   - Tsuru vs Modern Joining

- Tottori Prefecture (Kedaka)
- Okayama Prefecture
- Shimane Prefecture
- Modern Itozakura and Fujiyoshi

Introduction

Diversity of performance between traditional Black Wagyu bloodlines is widely discussed and we examine prefectural influences in this section.   However, the Japanese breeding trend is convergence towards a homogeneous, national Black Wagyu genetic core that has already absorbed those key traits from prefectural tsuru that are likely to deliver the ‘economic production’ benefits sought after. Hyogo prefecture remains the exception – and here traditional inbreeding continues.

For the remainder, although modern bloodlines are dominant, traditional prefectural bloodline names remain in use alongside modern strain nomenclature – usually based on the name of a foundation sire. So, for example, a sire might be described as ‘25% Shimane’ and ‘40% Itozakura’ – which also a Shimane-bred bloodline.

The purpose of this section is took look at both Traditional and Modern strains – identifying and attempting to resolve points of confusion.

So, for example, a sire might be described as ‘25% Shimane’ and ‘40% Itozakura’. In fact, a combination of Shimane tsuru and Shimane Modern – a total 65% Shimane prefecture breeding.

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Tsuru vs Modern Bloodlines

1.     Tsuru. The traditional, quarantined prefecture bloodline.  Japanese geneticists refer to these groups as sub-populations.  Historically, these sub-populations were proudly unique, today (for the most part) significantly endangered. Those reviewed are the key tsuru (linebred/female focus) herds unique to the prefectures of Tottori, Okayama, Shimane, Hiroshima and Hyogo.  The major concern for tsuru is the loss of genetic depth as lines die out within the traditional sub-populations, resulting from : a) extensive outcrossing continues in efforts to fix a limited number of traits  (for example, see Honda et al), or: b) intensive inbreeding targets a similar result.

2.     Modern. Modern Japanese ‘strains’ developed by outcrossing from tsuru.   Although each may be linked with a specific prefecture, the breeder has selected genetic resources from across the national herd with the objectives of breed improvement and trait fixing.   Such bloodlines developed rapidly in the post-1950s era when beef production had become the exclusive focus of contemporary Japanese breeding, often with the objective of ‘economical production’.  Targeting faster growth, earlier maturity, and increased yield.  With maintained marbling.  Examples are Itozakura and Fujiyoshi – in this case, virtually identical strains based on the same sire line, but from different prefectures.

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Tsuru vs Modern Joining

In the move away from quarantined prefectural ‘tsuru’ sub-populations, joining strategies have also changed, although a heavy emphasis on female selection remains.

a) Traditional “Tsuru” Joining. This is a unique Japanese ‘take’ on in-breeding. Following is an edited version of a web-published explanation authored by Dr. Kiyoshi Namikawa, an Executive Director of ZENWA, the Japanese Wagyu association.

Tsuru is a popular name for inbred strains of native cattle. It describes a group of related cattle within a strain, representing superior and common external and productive traits for that strain based on genetic make-up. EG: One tsuru group originated from one excellent cow which produced 19 calves over 23 years. Two daughters inherited superior dam characteristics, and they formed two sub-strains. A son was backcrossed to his dam to fix desired traits. Two bulls were selected among offspring produced by son and mother mating. Cows of this strain were sired with one of the bulls reciprocally in the successive generations. Most female progeny were held nearby to enable observation of performance.

Dr Namikawa emphasises that tsuru strains were founded on maternal lines, “because reproductive and growing performance records were observed only for females in some closed place from their farm.” For the original text see Namikawa, p3-4.

b) Modern Joining . As described in Predicting Wagyu Performance, modern Japanese Wagyu joining strategies are similar to contemporary Western assortative mating selection; frequently joining superior individuals from different sub-populations (often prefecture-based tsuru).

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