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Fertility related traits as cost reducing factors are of increasing concern to Holstein breeders. Dystocia and stillbirth represent important economic costs either direct (loss of calf, death of dam, veterinary assistance and labour) or long-term (culling rate, milk yield and fertility) ones (Meijering, 1984). In spite of low heritability (Kemp et al., 1988 (Meijering, 1984). Adjustments for such non-genetic factors are made in genetic evaluations (Berger, 1994;McGuirk et al., 1999;Fuerst and Egger-Danner, 2003).The incidence of dystocia and stillbirths tends to be population specific because of genetic factors and a range of non-genetic factors (Berry et al., 2007). The Czech Holstein population is specific in its development (conversion from the original Czech Fleckvieh cattle by upgrading crossing with Black and White and Holstein bulls) and in management conditions in herds. In the Czech Republic, data on the course of deliveries on farms have been recorded by breeders for more than ten years, but they have not been used for the genetic evaluation of calving traits yet. A model for the estimation of breeding value of calving difficulty in populations

The relative economic importance of traits was calculated for various crossbreeding systems in pigs. The in¯uence of the following three factors on the relation of standardised and discounted economic weights (SDEW) for reproduction and production traits was investigated: (i) the position of breeds in the crossing system, (ii) the use of breed-sex groups for mating in different tiers and (iii) the level of the management input parameters. The SDEW for each trait was calculated as the product of the marginal economic value, the genetic standard deviation and the number of discounted expressions. The ratio of SDEW for reproduction traits to SDEW for production traits was from 3 : 1 to 3.7 : 1 which is about twice the value of the corresponding ratio of undiscounted standardized economic weights (1.7 : 1). There were small differences in the ratio of standardized economic weights for number born alive and average daily gain (SDEWR) between males and females used for mating in the same tiers within a given crossing system (less than 1%). In each breed-sex group, there were signi®cant differences in the SDEWR (up to 24%) dependent on the use of this group for mating in different tiers within a given crossing system or in different crossing systems. This means that clients at multiplier and commercial levels should rank the genetic merit of their breeding stock differently from that of a common breeding objective. In crossing systems with two dam breeds without reciprocal crossing, the SDEWR was higher in the breed used in granddam position than in the breed used in grandsire position (about 20% under Czech conditions). Changes in the management parameters had only a minor impact on the SDEWR. ZusammenfassungFu È r verschiedene Kreuzungssysteme beim Schwein wurden relative o È konomische Gewichte berechnet mit dem Ziel, den Ein¯uss der Stellung der Rasse im Kreuzungssystem, der Verwendung der Rasse-Geschlecht-Gruppen fu È r die Anpaarung in verschiedenen Produktionsstufen und des Niveaus der Management-Input-Parameter auf das Verha Èltnis der standardisierten o È konomischen Gewichte (SDEW) fu È r Reproduktions-und Produktionsmerkmale zu untersuchen. Die Gro È ûe SDEW wurde fu È r jedes Merkmal als das Produkt aus dem Grenznutzen, der genetischen Standardabweichung und der Anzahl der diskontierten Merkmalsrealisierungen berechnet. Das Verha Èltnis zwischen SDEW fu È r Reproduktionsmerkmale und SDEW fu È r Produktionsmerkmale lag zwischen 3 : 1 und 3,7 : 1, d.h. war etwa doppelt so hoch wie das entsprechende Verha Èltnis der undiskontierten o È konomischen Gewichte (1,7 : 1). Fu È r das Verha Èltnis der standardisierten o È konomischen Gewichte der Anzahl lebend geborener Ferkel und der mittleren ta Èglichen Zunahme (SDEWR) wurden geringe Unterschiede (weniger als 1%) zwischen den Geschlechtern festgestellt, wenn sie innerhalb der gleichen Produktionsstufe des gegebenen Produktionssystems eingesetzt wurden. Innerhalb jeder Rasse-Geschlecht-Gruppe gab es gro È ûere Unterschiede im SDEWR (bis zu 24%) in Abha Èngigkeit da...

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