FACTORS AFFECTING OCCURRENCE OF RETAINED PLACENTA IN CATTLE - EFFECT OF SIRE ON INCIDENCE

Influences of defined factors on the incidence of retained placenta in dairy cattle of the Dutch Meuse-Rhine-Yssel breed were assessed from records of 246 066 selected calvings by 106 506 cows, resulting in a single live calf. Analysis of ten main effects and their interactions, indicated that increased incidences of retained placenta can be expected after difficult calving, with increasing age of the dam, after gestation periods of 260-270 days, and during June through August. Retention of the placenta at previous calvings increased the risk of recurrence by up to 50%. However, analysis of the same effects in a fixed model revealed an extremely low R2 value, indicating that although these factors are implicated in retained placenta most cases following normal parturitions have to be explained otherwise. Thus, a separate analysis of the influence of service sire and sire of dam was performed on a selected subset of retained placenta cases. The analysis included service sire, sire of the dam and the interaction of both effects. It appeared that in normal calvings preceded by gestation lengths of 275-284 days (population average) and with calves of 38-42 kg (population average), the effects on the incidence of retained placenta of both service sire and sire of the dam were highly significant. The effect of the interaction of both effects was not significant. It was also possible to group the sires and still obtain an equally good fit of the model. The effects of both sires are exerted in a cumulative fashion. Thus, the model can be used to predict retained placenta incidences in mating combinations, provided the data on incidences of retained placenta in sire offspring are available. On the basis of the present results, we think that it is feasible to consider the involvement of a genetic system, comprising a restricted number of genes, on the incidence of retained placenta.