Fertilizing capability of breeding boars by evaluation of the early pregnancy factor in test sows

The fertilizing ability of breeding boars was evaluated on the basis of an early pregnancy factor (EPF) determined in the blood serum of test sows by the method of rosette inhibition. The fertilizing ability was tested in ten boars on an insemination farm: the fertilizing potency of 41 ejaculates was evaluated from the percent conception of 105 test sows. The percent conception of test sows was evaluated from the EPF positive findings in the blood serum of these sows in the average range of 8.02 +/- 1.70 days (the range of 2 to 11 days) after insemination and from the recorded deliveries. The evaluation of the fertilizing of boars on the basis of EPF in test sows revealed in most cases the higher fertilization rate than could be found on the basis of the recorded deliveries of test sows. There was an exception to this trend: one breeding boar with a paradoxical finding of the somewhat higher percentage of deliveries recorder in test sows, in comparison with the fertilization ability according to the results of EPF. Identical results of the two criteria of fertilizing ability were recorder in another boar with a small number of tested ejaculates and test sows. The average fertilization of the whole set of the breeding boars, expressed by the average percent conception of all test sows, reached 86.67% on the basis of the EPF positive findings in 2 to 11 days after insemination, and 67.31% on the basis of recorded deliveries. These differences in fertilization are likely to be related to the share of dams and can be ascribed to embryonic mortality.