Production of SPF Akita giant rabbits

1. Production of SPF Akita giant rabbits ○ Yukihisa Matsuda１）、Yoshiko shibata１）、Keita Basaki１）、Yasuyoshi Fukuda１）、Yuko Tsuya２）1) Animal Research Laboratory, Bioscience Education-Research Center, Akita University, 2) JAC, The Care Taker of Laboratory Animals

2. Ｈｉｓｔｏｒｙ　ｏｆ　Akita giant rabbits In around Daisen City of Akita Prefecture (Fig.1), rabbits for food materials have been reared since over 100 years ago. For ten decades those rabbits have been enlarged in body size through cattle fair held every year by their owners (Fig.2, 3). Fig.1 Fig.2 Fig.3

3. Relationship between number and body weight of Akita giants rabbits exhibited in cattle fair of each year The number of Akita giant rabbits exhibited in cattle fair are decreasing every year by decrease of farm owners.

4. Use the giant rabbits for animal research We used those Akita giant rabbits(AGR) as experimental animals instead of dogs and cats in orthopedic or cardiovascular research and got good results in every research region. Fig. 5 Tibia and femur Fig. 6 Common carotid artery Fig. 4 Body size JW AGR JW AGR JW AGR

5. Diseases of Akita giant rabbits Most of GR had infectious diseases, especially respiratory infections(Table 3, Fig 7), so it was difficult constantly to supply them to research laboratory as they were. Fig. 7

6. Production of SPF Akita giant rabbits Therefore we tried to produce SPF giant rabbits with using caesarian section and foster mother method. As a result of such trials we obtained SPF giant rabbits (JW-AKT) 20 years ago . Fig.8 shows growth curve of JW-AKT and KBL (KITAYAMA LABES., CO LTD. ). Biochemical data of serum are shown table 4. There is no different from normal Japanese white rabbits in those values. Unfortunately we could not continue to maintain SPF colony because of reproductive disturbance by inbreeding depression. Retrial to produce JW-AKT was difficult because of marked increase in gene modified mice. Fig. 8

7. Retrial of producing JW-AKT • SPF rabbit room was secured in March 2009 as results of reconstruction and expansion of animal facilities(Fig.9). • Large cages with W653×D653×H450mm(TECNIPLAST, JAPAN co., Ltd, Tokyo) were used for giant rabbits(Fig.10) • Retrial of producing SPF giant rabbitsstarted from Apple 2010. • Rabbits were fed Labo R stock (NOSAN) and drunk by Automatic watering system Fig.9 Fig.10

8. Methods of producing JW-AKT • Caesarian section (CS) and foster mother method • Transplantation of fertilized eggs (TFE) method (Fig. 11) • JW-AKT natural delivery method • Artificial insemination (AI) method (fig.12, 13) Fig.12 Fig.11 Fig.13 About 10 fertilized eggs( 2days after mating AGR) were transplanted from fimbriae into oviduct of recipient (KBL) AGR sperm were collected using with artificial vagina AGR sperm diluted by TCG buffer were injected into vagina of JW-AKT by artificial insemination

9. The relationship between the number and body weight of newborns *Data of KITAYAMA LABES **Part of newborns

10. Growth curves of JW-AKT and KBL g (n=3) (n=5) (n=6) (n=7) weeks

11. The situation of rearing Akita giant rabbits Number of rearing heads Number of owners 1990 1991 2002 1995 1996 1998 1999 2000 2001 1997 Fiscal year Reference in data of Akita prefecture The number of Akita giant rabbits and their owners in Daisen area are decreasing every year.Valuable genes of Akita giant rabbits are in danger of extinction.

12. Conclusion • In this study, we succeed with reproducing JW-AKT, and got largest female one with over 7kg at 34 weeks (Fig. 14). • The growth curves of JW-AKT between 20 years ago group and this study group were similar and there were no significant difference in male and female body weight at 31 weeks, respectively. • From results of this study, we considered that it will be able to maintain JW-AKT colony with using AI based on Akita giant rabbits rearing in Daisen area. • Furthermore, we consider that the technique such as cryopreservation of sperm and fertilized eggs will be able to contribute in protecting AGR in Daisen area from anxious reproductive disturbance by inbreeding depression. Fig. 14