Limiting effects of uterine crowding on the number and weight of live pups at birth in hemiovariectomized and normal rabbit does.

Variation in the number, total weight, mean individual weight and minimum individual weight of live pups at first and second litter were studied in hemiovariectomized (H = 54 does) and normal (N = 55 does) rabbit does. The total number of implanted embryos in 25 unoperated (N) and 54 hemiovariectomized (H) does were recorded by laparoscopy on the 12th day of their second pregnancy. The total number of implanted embryos was not statistically different between experimental groups (m +/- SEM; H: 11.0 +/- 0.4; N: 12.4 +/- 0.5; P = 0.06). The number of total pups at birth (H: 7.7 +/- 0.2 vs N: 9.8 +/- 0.2; P < 0.01) was affected by hemiovariectomy even when analyzed as a constant total number of implanted embryos. The number of live pups (H: 7.0 +/- 0.2 vs N: 9.0 +/- 0.3; P < 0.01), the total weight of live pups (H: 395 +/- 11 g vs N: 479 +/- 12 g; P < 0.01), the mean litter weight (H: 58.9 +/- 1.1 g vs N: 54.1 +/- 0.7 g; P < 0.01) and the minimum individual weight of live pups at birth (H: 46.5 +/- 1.4 g vs N: 42.1 +/- 1.0 g; P < 0.05) were also affected by hemiovariectomy. The significance of hemiovariectomy effect disappeared when analyzed as a constant total number of pups at birth. A positive non-linear relationship between the total number of pups at birth and the total weight of live pups was detected.(ABSTRACT TRUNCATED AT 250 WORDS)