动物造模 z-bio 2022-04-28 378

　　Objective To systematically study the effects of different first mating days on the reproductive performance of NIH mice.

　　Methods This experiment was divided into 4 groups according to the age of first mating, 30 pairs of mice on 50, 60, 70, and 85 days each, and the reproductive performance of each pair of mice was recorded from the 1st to 6th litters.

　　Results There were significant or extremely significant differences in litter size, weaning number, weaning rate, birth and average body weight of weaned mice between the 70-day and 85-day groups and the 50-day group (P<0.05, P<0.01). ;Compared with the 60 d group, there were significant differences in the average birth weight and weaning number (P<0. p="">0. 05); the average litter size of the 2nd to 3rd litter and the first litter in NIH mice The ratio was significantly increased (P<0.05), and the 5th to 6th pregnancies were significantly decreased (P<0.05); the weaning number of the 3rd to 4th pregnancies was different from that of the 1st pregnancies (P<0.05). 05); the average body weight and weaning rate of newborn mice increased with the increase of parity (P<0.05, P<0.p="">0.05).

　　Conclusion NIH mice have good reproductive performance at 70-85 days of age, and the reproductive performance of the 2nd-3rd litter is stable. It is recommended to breed to the sixth litter.