Selecting and Establishment of a Low-Incidence Hydronephrosis Wistar Rat (Mlac:WR) Colony at the National Laboratory Animal Center, Mahidol University, Thailand

Abstract

This study established a low incidence hydronephrosis Wistar rat (Mlac:WR) colony at the National Laboratory Animal Center, Mahidol University, Thailand. Twenty Mlac:WR breeding pairs were randomized to determine the percentage of hydronephrosis in the original National Laboratory Animal Center colony. Hydronephrosis was discovered in 9.66% of the population. Breeder selection for breeding was carried out by using the progeny selection method, which selects offspring based on their characteristics, in combination with the breeding principle of maximum avoidance of inbreeding and the rotational mating system. Breeding pairs that produced hydronephrosis offspring were removed from the colony and replaced with offspring from other healthy breeding pairs within the same group in the next generation. The results from selection and breeding revealed that the incidence of hydronephrosis was 7.5% in the F0, decreasing to 1.07%-1.72% in the F2-F4, and 0.00% in the F5. However, the incidence of hydronephrosis was found at 0.49% in the F6-F7, decreasing to 0.00% in the F8, and was found again at 0.42%-1.02% in the F9-F10. This is because hydronephrosis traits are genetically linked and controlled by several genes. Therefore, it cannot be completely eliminated from the population.