Geplaatst: 29-01-12 12:11 Citaat:Osteochondrosis (OC) is an important orthopedic developmental disorder in
many horse populations. A review of the literature reveals widely variable
heritability estimates for the disorder. We estimated the genetic parameters
(heritabilities and genetic correlations) of various manifestations of OC.
Femoropatellar, tarsocrural, and metacarpophalangeal/ metatarsophalangeal
joints of 811 randomly selected yearlings from the Royal Warmblood Studbook
of the Netherlands (KWPN), descending from 32 representative stallions, were
scored for OC at 28 predilection sites. At each site, OC was scored in 5
categories, distinguishing between flattened bone contours and fragments. At
the animal level, the overall heritability of OC was 0.23, the heritability of
flattened bone contours was 0.08, and the heritability of fragments was 0.22. At
the joint level, heritability was highest in the tarsocrural joints, intermediate in
the metacarpophalangeal/ metatarsophalangeal joints, and lowest in the
femoropatellar joints. The heritability estimates for the contralateral joint
homologues were very similar. The genetic correlation between the tarsocrural
and femoropatellar joint was high, whereas correlations between the
metacarpophalangeal/ metatarsophalangeal and other joints were moderate.
The genetic correlation between flattened bone contours and fragments at the
animal level was 0.80. Scoring OC on a 5-point categorical scale resulted in
higher heritability on the observed scale than when analyzing OC as a binary
trait. Our results suggest that selection against OC could best be performed by
taking into account the OC status of all 4 joints, the femoropatellar, the
tarsocrural, and the metacarpophalangeal/metatarsophalangeal joints, and
discerning between flattened bone contours and fragments.
Blijkbaar zijn de correlaties dus toch aan de hoge kant, waardoor er wel degelijk 1 waarde kan geschat worden.
Echter staat hier dat er wordt aangeraden om OC en OCD apart te nemen...
En ik blijf erbij, 20 nakomelingen screenen is nihil. Ik heb zelf genetische paramaters geschat voor m'n eindverhandeling waar ik bij 1 hengst 1120 nakomelingen in m'n dataset had...
Maar, voor alle duidelijkheid, ik ben absoluut voor dit onderzoek naar OCD vererving! Hoe meer gegevens geweten hoe beter! Alleen vind ik dat hun model wel eens mogen uitleggen ook (de verschillende onafhankelijke factoren die ze gebruikt hebben), of gebeurt dat ik het artikel in IDS?
