Feet and leg problems are of great concern to dairy producers since they are a major cause for unplanned, premature and costly culling of cows in dairy herds. Conventional selection so far in most populations has failed to improve upon this situation due to low heritabilities of the traits in question. Marker assisted selection based on the identification of QTLs should offer greater benefits. However, in a number of studies (e.g. Ashwell et al., 1998a ; Ashwell et al., 1998b ; Schrooten et al., 2000 ; Boichard et al., 2000) using grand-daughter designs and whole genome scans, a variety of QTLs have been reported on several chromosomes (9, 22, 23, 16, 24, 15) for the closely related traits foot angle, foot diagonal and heel depth. The variety of traits and chromosomes and given the fact that the Holstein sub-populations around the world should be closely related may indicate that it will be difficult to identify an important QTL based on the phenotypes used so far as these commonly are provided by national type scoring systems. In contrast to the studies mentioned, Baumgartner et al. (2002) reported a QTL influencing heel depth on BTA 7 based on direct measurements of the trait in bulls of age around 14 months. However, the authors were unable to verify this finding in a data set consisting of breeding values of A.I. bulls for linear type scores of their daughters. In the present study a larger data set of estimated breeding values for feet and leg traits of A.I. bulls could be used and all relevant traits were analyzed simultaneously.
Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 2002. Session 1, , 1.43, 2002
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