The aim of this review was to summarize new genetic approaches and techniques in the breeding of cattle, pigs, sheep and horses. Often production and reproductive traits are treated separately in genetic evaluations, but advantages may accrue to their joint evaluation. A good example is the system in pig breeding. Simplified breeding objectives are generally no longer appropriate and consequently becoming increasingly complex. The goal of selection for improved animal performance is to increase the profit of the production system; therefore, economic selection indices are now used in most livestock breeding programmes. Recent developments in dairy cattle breeding have focused on the incorporation of molecular information into genetic evaluations and on increasing the importance of longevity and health in breeding objectives to maximize the change in profit. For a genetic evaluation of meat yield (beef, pig, sheep), several types of information can be used, including data from performance test stations, records from progeny tests and measurements taken at slaughter. The standard genetic evaluation method of evaluation of growth or milk production has been the multi-trait animal model, but a test-day model with random regression is becoming the new standard, in sheep as well. Reviews of molecular genetics and pedigree analyses for performance traits in horses are described. Genome -wide selection is becoming a world standard for dairy cattle, and for other farm animals it is under development.
ABSTRACT:The Old Kladruber horse is an important Czech genetic resource. In the current study, two categories of traits were evaluated -the first, a numerical score for Type and Gender Expression and the second, 11 traits describing performance divided into four categories: (1) Rideability (Overall Impression, Rideability), (2) Gaits (Walk, Trot, Canter), (3) Carriage Drivability (Dressage Test, Obstacle Driving Test, Marathon Test), and (4) Reliability in Tug (First Tug, Second Tug, Third Tug). The original data set contained records from 700 individuals from the period 1995-2014, each horse having 3-5 performance evaluations for the suite of traits. Our objective was to identify a suitable model for the estimation of genetic parameters and prediction of breeding values. Only one model was examined for the Type and Gender Expression trait, whereas three models were compared for the analysis of each performance trait. Criteria for choosing the most appropriate model were minimal values for the deviance information criterion (DIC) statistics, low ratios of residual variance to phenotypic variance, and maximal heritability estimates. The heritability estimate for Type and Gender Expression was 0.18. For the performance traits, the model with the fewest sources of variation (model 1) was more appropriate than two alternatives with more sources of variation. Heritability estimates from this model ranged from 0.08 to 0.40, while estimates for various performance traits from the other models were in the range 0.08-0.24. Low heritabilities for several of the performance traits suggested that selection for their genetic improvement would likely be unsuccessful. In order to maintain genetic variability, inbreeding, and fitness in the Old Kladruber population we suggest to use breeding value estimation using the heritabilities and the method presented in this paper.
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