A new approach to estimating the allele frequencies of lethal autosomal-recessive genetic disorders was developed based on the gene dropping method. The method was tested in the complex pedigrees of 1 830 125 animals of the Austrian Brown Swiss population, where carriers for 4 genetic disorders were recorded. Trends of allele frequencies of Spinal Dysmyelination and Spinal Muscular Atrophy increased while Weaver decreased, but allele frequencies of Arachnomelia fluctuated between 2 and 3 %. The results were compared to the results from other methods. The results obtained from probability of gene origin were higher than the results from gene dropping in general, while the results from gene counting were lowest due to the fact that just a part of the pedigree information could be considered by the used program. The gene dropping and gene counting methods used here take lethal selection into account, while the program based on probability of gene origin does not. Therefore, gene dropping and gene counting seem to be more appropriate for estimating the lethal allele frequency of lethal autosomal-recessive genetic disorders. Applying the gene dropping approach, one can obtain the distribution of allele frequencies and confidence intervals for the allele frequency, which might be valuable for observing trends in active breeding populations. Keywords

Abstract. Microsatellite analysis was used to estimate genetic diversity and relationship of 180 individuals belonging to two native endangered Austrian cattle breeds, Carinthian Blond (CB) and Waldviertler Blond (WV), and Hungarian Grey (HU) from Hungary. Twenty-five markers were used, and a total of 213 alleles were detected, of which 54 alleles (~25 %) were private alleles. Three breeds are clearly separated from each other with a correct assignment higher than 90 %. No bottlenecks were detected in any of the populations. A small amount of gene flow among the three populations occurred in the past. The closest genetic relationship is between Carinthian Blond and Waldviertler Blond (NEI et al.’s distance DA, [1983]; DA=0.11). However, Carinthian Blond showed higher mean number of alleles per locus (6.76), number of private alleles (17) and expected heterozygosity (0.663) than Waldviertler Blond (6.04, 9 and 0.631, respectively). The negative values of fixation index FIS (−0.018 and −0.037 for CB and WV, respectively) indicated that inbreeding is avoided, a sign for a successful conservation breeding program.

Genetic parameters were estimated for stillbirth, calving ease and gestation length in three endangered Austrian blond cattle breeds, Carinthian Blond, Murboden and Waldviertel Blond. REML analysis based on an animal model including direct and maternal genetic effects was applied. Direct heritability estimates for calving ease, stillbirth and gestation length varied from 0.003 to 0.111, 0.006 to 0.044 and 0.235 to 0.512, respectively, while maternal heritabilities ranged from 0.001 to 0.007 for calving ease, 0.005 to 0.014 for stillbirth, and 0.002 to 0.063 for gestation length. All pairwise genetic correlations for direct traits were generally moderate to high except for stillbirth-calving ease (−0.077, Carinthian Blond). The genetic correlations of all pairs of the 3 direct traits were positive for Murboden (0.520 to 0.700) and Waldviertel Blond (0.253 to 0.707) while negative genetic correlations were detected for Carinthian Blond (−0.077 to −0.943). Close positive genetic correlations were found between direct stillbirth and calving ease of Murboden (0.700) and between direct calving ease and gestation length of Waldviertel Blond (0.707), while a close negative genetic correlation was found between direct calving ease and gestation length of Carinthian Blond (−0.943). Keywords