Anotace:
In this study, inbreeding and effective population size of the Latvian gene conservation cattle breeds Latvian Brown (LB) and Latvian Blue (LZ) were analysed. The study was based on the pedigree data of 319 LB and 712 LZ cows that were alive at the time of data selection. The inbreeding level in LB and LZ has been increasing during the last decade and at the end of the year 2019, it was 2.61% and 5.20% for LB and LZ, respectively. The average increase of inbreeding from 2010 to 2019 was 1.80% for LB and 2.26% for LZ. The proportions of inbred animals with an inbreeding level greater than 10% were 0.60% and 2.14% in LB and LZ, respectively. Effective population size based on the rate of inbreeding decreased and was close or within the minimum range of recommended effective population size. The current study demonstrates that the inbreeding has increased, and the effective population size decreased in both populations. Therefore, the breeding organizations have to monitor and control the rate of inbreeding in LB and LZ populations over time.