Browsing by Subject "genetic correlation"

Genetic and phenotypic parameters and relationships for fertility traits, body type traits and production were estimated. The data analyzed included 21,450 Ayrshires. Animals were reared in 2,647 herds, born from 1994 to 2005 and were progeny of 1652 sires. Analyzed fertility traits were days from first service to last insemination and number of inseminations to conception for heifers, and days from calving to first insemination for first parity cows. Production traits were first lactation milk and lifetime milk and body type traits were stature, body depth, chest width, angularity, top line, rump width and rump angle. Variance components and the heritability estimates were calculated by restricted maximum likelihood (REML) method using the DMU software. The heritability estimates of first lactation milk yield and lifetime milk yield were 0.28 and 0.08, re-spectively. The heritabilities for fertility traits in virgin heifers and first lactation cows were low (0.02 – 0.03). Heritability estimates for the type traits varied from 0.10 to 0.43. The largest heritability was found for stature (0.43) and rump width (0.27). The highest positive genetic correlations were angularity with first lactation milk (0.41) and lifetime milk (0.45), and the highest negative genetic correlation was between top line and first lactation milk (-0.33). Chest width and rump angle had a positive genetic correlation to days from calving to first insemination. The significant genetic correlations were heifer fertility with body depth, rump width and rump angle. Estimated correlations between heifer fertility traits and lifetime milk yield were positive and moderate. First parity cow fertility was not related to production traits. Fertility traits and lifetime milk have a low heritability. Progress can be made relatively fast in body traits and first lactation milk by breeding, because of the moderate heritabilities. Selection for some body type traits may cause improvement in production but deterioration in fertility. Declined heifer fertility is associated with high lifetime production. However is not reasonable to put emphasis on poor heifer fertility in selection.

The aim of this study was to investigate the genetic relationships between conformation and performance traits in Finnish Warmblood riding horse population. The research material included the RHQT (riding horse quality test) results from the years 1996-2010 and the pedigree data for the horses. The RHQT results were received from the Finnish Breeders Association and the pedigree data was received from the Finnish trotting and breeding association’s horse register. The RHQT results consisted of 640 horses and the pedigree data consisted of 4 458 horses. The REML estimates of (co)variance components were calculated by VCE6 using multi trait model. Altogether there were six trait groups, which consisted of 27 different traits. Because of the large number of traits, the analyses were done in smaller subsets with two trait groups at the same time. The heritability estimates for the studied traits were quite high and the standard errors were small. The genetic correlations within each trait group were strong and positive. Thus it could be concluded that same genes or groups of genes affect all the traits within the trait group. The other explanation for this could be that in reality the judges have evaluated the same traits as different traits. The genetic correlations between conformation traits and all gait traits and dressage traits indicate that conformation can be used indirectly in the breeding of gait and dressage traits. Furthermore, it could be concluded that the genetic relationships between conformation and show-jumping traits are quite low. The genetic correlations between gait traits and show-jumping traits were low. The genetic correlations between gait traits and dressage traits were positive and strong. These strong and positive correlations indicate that the judged traits are actually same or very similar. From the results of this study can be concluded that all three different tests for show-jumping traits are actually measuring the same traits. Because of this one test would be adequate to produce the information of horses quality, capacity and breeding value. Moreover it can be concluded that there are genetic relationships between conformation and performance in Finnish Warmblood riding horse population. These discovered relationships can be used when breeding traits that have low heritabilities, such as the mechanic of movement in the walk or rideability. Furthermore, these results can be used to improve the judging methods in RHQT and other performance tests.