An indication of major genes affecting hip and elbow dysplasia in four Finnish dog populations

The aim of the study was to assess the possible existence of major genes influencing hip and elbow dysplasia in four dog populations. A Bayesian segregation analysis was performed separately on each population. In total, 34 140 dogs were included in the data set. Data were analysed with both a polygenic and a mixed inheritance model. Polygenic models included fixed and random environmental effects and additive genetic effects. To apply mixed inheritance models, the effect of a major gene was added to the polygenic models. The major gene was modelled as an autosomal biallelic locus with Mendelian transmission probabilities. Gibbs sampling and a Monte Carlo Markov Chain algorithm were used. The goodness-of-fit of the different models were compared using the residual sum-of-squares. The existence of a major gene was considered likely for hip dysplasia in all the breeds and for elbow dysplasia in one breed. Several procedures were followed to exclude the possible false detection of major genes based on non-normality of data: permuted datasets were analysed, data-transformations were applied, and residuals were judged for normality. Allelic effects at the major gene locus showed nearly to complete dominance, with a recessive, unfavourable allele in both traits. Relatively high estimates of the frequencies of unfavourable alleles in each breed suggest that considerable genetic progress would be possible by selection against major genes. However, the major genes that are possibly affecting hip and elbow dysplasia in these populations will require further study.

Estimates of genetic parameters for hip and elbow dysplasia in Finnish Rottweilers

Data from 2,764 Rottweiler dogs born from 1987 to 1996 were analyzed with a Restricted Maximum Likelihood procedure using a mixed linear animal model to obtain variance component estimates for hip and elbow dysplasia. The data included 2,764 hip dysplasia and 2,278 elbow dysplasia records. Hip joints were scored as normal (0), borderline (1), slight (2), moderate (3), and severe (4, 4.5, and 5) hip dysplasia. Elbow joints were graded normal or borderline (0), slight (1), moderate (2), and severe (3) elbow dysplasia. The mean for the hip scores was 1.07 and for the elbow scores .60. Environmental effects influencing hip dysplasia were age, birth year, birth year x season interaction, and experience of the veterinarian responsible for x-raying the dog. For elbow dysplasia, statistically significant effects were age, birth year, sex of the dog, and panelist responsible for each screening. Estimates of heritability for hip and elbow dysplasia were .58 +/- .04 and .31 +/- .04, respectively, with a genetic correlation of .37 +/- .08 between the traits. Genetic improvement of almost one genetic standard deviation was observed in both traits during the 10 yr covered by the data.

Combining selection for carcass quality, body weight, and milk traits in dairy cattle

Alternative selection strategies were evaluated for breeding for carcass quality, body weight, and milk traits in dairy cattle. The efficiency of different alternatives was evaluated by comparing predicted genetic responses in individual traits as well as in the aggregate genotype. Particular interest was paid to the loss of response with indices that partially or totally ignored genetic correlations between traits, reflecting selection on single-trait evaluations. Simplified indices gave almost the same total response as a full multiple-trait index, but relative responses in carcass and milk traits differed between indices. Also studied were the consequences of restricting increase in body weight of dairy cows, while selecting for carcass and milk production traits. Restriction of body weight of cows resulted in considerable loss of predicted total response.

Estimates of genetic parameters and environmental effects for measures of hunting performance in Finnish hounds

Data from field trials of Finnish Hounds between 1988 and 1992 in Finland were used to estimate genetic parameters and environmental effects for measures of hunting performance using REML procedures and an animal model. The original data set included 28,791 field trial records from 5,666 dogs. Males and females had equal hunting performance, whereas experience acquired by age improved trial results compared with results for young dogs (P < .001). Results were mostly better on snow than on bare ground (P < .001), and testing areas, years, months, and their interactions affected results (P < .001). Estimates of heritabilities and repeatabilities were low for most of the 28 measures, mainly due to large residual variances. The highest heritabilities were for frequency of tonguing (h2 = .15), pursuit score (h2 = .13), tongue score (h2 = .13), ghost trailing score (h2 = .12), and merit and final score (both h2 = .11). Estimates of phenotypic and genetic correlations were positive and moderate or high for search scores, pursuit scores, and final scores but lower for other studied measures. The results suggest that, due to low heritabilities, evaluation of breeding values for Finnish Hounds with respect to their hunting ability should be based on animal model BLUP methods instead of mere performance testing. The evaluation system of field trials should also be revised for more reliability.