近交系クラウンミニブタの体尺測定値と特徴について

Increasing demands are being noted for miniature pigs in experimental uses as one of the large experimental animals as biomedical researches have made rapid progress in recent years. Our research project was initiated in 1978 at the Laboratory of Animal Reproduction in Kagoshima University. A boar and two sows of cross-bred strain of Ohmini miniature pig were introduced to the Laboratory and maintained therein as a closed group. Changes in the inbreeding coefficient, litter size, weaning rate, body weights, measurements of bodies, and characteristics of CLAWN miniature pigs were investigated in the meantime. The results were summarized as follows.<br>1. Six to seven generations were achieved in the piglets born up until 1989 since the introduction of the priginal crossbred pigs into our laboratory in 1978. The whole term of our investigation was roughly divided into 3 terms and the mean inbreeding coefficients of the 3 groups were checked to find that it was less then 12.5%, 28.2% and 41.4% in the first term (1978-1980), the second term (1981-1985) and the third term (1986-1989), respectively. The highest inbreeding coefficient shown by onf of them was as high as 57.0%.<br>2. The mean litter size was 5.0 (n=45) from among all the farrowings during the whole period of study. It wbs 5.7 in the first term and 4.7 in the third term, showing a decrease by one piglet. On the other hand, the differences in litter size by the season of farrowing revealed 5.5 in spring, 5.1 in summer, 5.0 in winter and 4.0 in fall. Tiis finding may suggest that the litter size was more influenced by seasons, especially by the mating in summar, than by the increase in the inbreeding coefficient.<br>3. The mean weaning rate was 78.0% during the whole period of study. It was reduced from 77.2% in the first term into 74.5% in the third term, a drop of 2.7%. By seasons of farrowing, the farrowing rate was 72.7%, 90.2%, 77.5% and 66.0% in spring, summer, fall and winter, respectively. The one in winter showed a sharp drop.<br>4. In terms of main measurements of bodies (body weights, lengths and body heights), the three measurements at birth were 0.55kg in males, and 0.50kg in females only weights bt birth, 20.5kg, 74.6cm and 39.5cm in males and 23.7kg, 74.7cm and 38.9cm in females at 6 months of age, 36.7kg, 88.6cm, and 47.9cm in males and 40.1kg, 87.3cm and 44.9cm in females at 12 months of age and 48.6kg, 100.2cm and 54.0cm in males and 58.1kg, 94.9cm and 51.5cm in females at age of 18 months.<br>5. CLAWN miniature pigs are mostly in white color, but some have black spots on the body. Totally black colored ones were noted in 13.7% of them during the whole period of our study. They are tame and meek.<br>It can be claimed that CLAWN miniature pigs have thus been established as an inbred strain of miniature pigs, as it is of a small size, white color and tame for easy handling. It is therefore hoped that it be subjected to propagation in a larger scale and effective uses.