李茂盛 李世昌 張秀鑾 吳明哲
THE INFLUENCE OF FARROWING MONTH AND FRATERNAL
BODY WEIGHT OF NURSING PUPS IN NEW ZEALAND WHITE RABBIT
M. S. Lee, S. C. Lee, H. L. Chang and M. C. Wu
Taiwan Livestock Research Institute
A total of 5217 litters of New Zealand White rabbits was recorded from January of 1990 to December of 1997. The influence of farrowing month and fraternal size on body weights of pups at birth and 3-week old and their survival rate. The birth weight of pups was the heaviest one, 68.2g, when they were born in January and February. It was significantly heavier than that of pups born in June to August (57.3g). They weighed 400.6 and 329.1g at 3-week old, respectively. Survival rates of 3-week old pups born in February and July were 89.7 and 81.0%, respectively. Three fraternal size groups: small (1~3 alive pups), medium (4~8 alive pups) and large (9~17 alive pups) were classified according to the number of born alive. Pups in the small group had a heaviest birth weight and 3-week old weight and a greatest survival rate. Birth weights of pups in the small, medium and large groups were 75.6, 61.6 and 53.5g; 3-week old weight were 473, 344 and 282g; and survival rate at 3-week old were 93.3, 87.0 and 77.0%, respectively (P<0.05). Results indicated that a summer depression on birth weight of pups and their 3-week old weight and survival rate existed in the summer of Taiwan. Nursing pups in the large fraternal size group increased only 5.3 times on body weight at 3-week old and it was significantly less than that of the small (6.3 times) and medium (5.6 times) groups.
Key Words: Rabbit, Season, Body weight.