Production of SPF Akita giant rabbits

○ Yukihisa Matsuda １）、 Yoshiko shibata １）、 Keita Basaki １）、 Yasuyoshi

Fukuda １）、 Yuko Tsuya ２）

1) Animal Research Laboratory, Bioscience Education-Research Center, Akita

University, 2) JAC, The Care Taker of Laboratory Animals

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).

Ｈｉｓｔｏｒｙ　ｏｆ　 Akita giant rabbits

Fig.1 Fig.2 Fig.3

Relationship between number and body weight of Akita giants rabbits exhibited in cattle fair of each year

BWYear

4-6kg 6-8kg Over 8kg SUM

1992 56(42%)

62(46%)

16(12%)

134(100%)

1993 65(45%)

56(39%)

22(15%)

143(100%)

1994 54(50%)

49(45%)

5(5%)

108(100%)

2013 36(42%)

33(39%)

16(19%)

85(100%)

The number of Akita giant rabbits exhibited in cattle fair are decreasing every year by decrease of farm owners.

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.

JW AGR JW AGR JW AGR

Fig. 5 Tibia and femur Fig. 6 Common carotid arteryFig. 4 Body size

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

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

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 rabbits started from Apple 2010.• Rabbits were fed Labo R stock (NOSAN) and drunk by Automatic

watering system

Fig.9 Fig.10

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)

About 10 fertilized eggs( 2days after mating AGR) were transplanted from fimbriae into oviduct of recipient (KBL)

AGR sperm diluted by TCG buffer were injected into vagina of JW-AKT by artificial insemination

AGR sperm were collected using with artificial vagina

Fig.11 Fig.13Fig.12

The relationship between the number and body weight of newborns

Fertilization & delivery

Number of

newborns

Body weight of newborns(0 day)

Survival number after weaning

Natural mating (KBL) &natural delivery(4 heads ) 26 60.8±8.9g* 24

TFE of giant rabbit to KBL & natural delivery(12 heads ) 19 60.0±12.5g** 1

TFE of AGR to KBL & CS(1 head) 1 125g 1Natural mating (AGR) &SC(1 head) 9 54.6±10.0g 5Natural mating (JW-AKT) &natural delivery(1 head) 14 50.7±10.0g** 2

AI with AGR sperm to JW-AKT & natural delivery(3 head) 25 - 15

*Data of KITAYAMA LABES**Part of newborns

Growth curves of JW-AKT and KBL

0 5 10 15 20 25 30 350

1000

2000

3000

4000

5000

6000

7000

(n=3)

(n=5)

(n=7)

(n=6)

weeks

g

Reference in data of Akita prefecture

The situation of rearing Akita giant rabbits

heads

Fiscal year1990 1991 1995 1996 1997 1998 1999 2000 2001 2002

Number of rearing

Number of owners

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.

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