Systematic effects on the occurrence of abomasal displacements in German Holstein cows

The objectives of this study were to analyse risk factors for the prevalenc e of abomasal displacement in German Holstein cows. Particularly, the inves tigation should show, whether a genetic disposition for the abomasal displa cement may be exist. In the period from 02/01/ 1999 to 01/31/2000 five vete rinary surgeons in Northern Lower Saxony registered all cases of abomasal d isplacement in German Holstein cows being under the official milk I recordi ng scheme. In total, the investigation included 160 farms and 9315 cows. An abomasa displacement was registered in 151 German Holstein cows, correspon ding to a frequency of 1.6%The left abomasal displacement (74.8%) was recor ded more often than the right abomasal displacement (25.2%). The influences of the calving month, the lactation number, the age at calving, calving pe rformance, duration of pregnancy, and the inbreeding coefficient did not ex plain a significant part of the variation of the frequency of the abomasal displacement. Significant effects of the sire and the herd were obtained fo r the leftsided abomasal displacement. For the rightsided abomasal displace ment and for all abomasal displacements the herd effect was not significant , Heritability estimates using bivariate linear REML models were h(2) = 0.0 34 +/- 0.009 for the leftsided abomasal displacement, and h(2) = 0.004 +/- 0.005 for the rightsided abomasal displacement, Using the threshold model t he heritabilities for the left abomasal displacement yielded estimates of h (2) = 0.41 and for the right abomasal displacement of h(2) = 0.11, respecti vely. The analyses showed a genetic predisposition for the displacement of the abomasum in German Holstein cows.