Impact of crossing system on relative economic weights of traits in purebred pig populations

Abstract

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...

Genetic parameters for carcass weight, conformation and fat in five beef cattle breeds

“…The relative emphasis of the traits in an index was calculated as the proportion of a trait's standardized economic value (a S = a σ G ) from the total sum of all standardized values (relative importance of a trait = a S /Σ a S ; Wolfová et al, 2001). Genetic responses in the three traits (R) were calculated as R ¼ i σ I b 0 G, where i is the selection intensity (set to 0.5), σ I the standard deviation of the selection index, b the vector of three selection index weights and G the 3 × 3 genetic (co)variance matrix for the three traits, and σ I was calculated as σ I ¼ ffiffiffiffiffiffiffiffiffiffi b 0 Pb p , where P is the 3 × 3 phenotypic (co)variance matrix and b = P − 1 Ga, where a is the vector of the three economic values.…”

Economic weights for sow productivity traits in nucleus pig populations

“…Wilton et al (2002) distinguished between selection indices appropriate for breeders at the nucleus level, which are linear (Goddard, 1993), and those used at the commercial level, which may be non-linear, in order to account for factors such as heterosis and non-linear price grids. Smith et al (1983) and Wolfova et al (2001) found that economic weights also depended on the type of crossbreeding system, the breeding role of the stock, the management system, and the criteria of economic efficiency used in the production system. National or regional selection indices for purebred breeding stock are based on the average market requirements and a typical production system.…”

Realized effect of different selection criteria applied in breeding herds on performance in multiplier herds

“…Thus, commercial animals are crossbreds but genetic selection is based on purebred performance. Likewise, the economic weights should also depend on the type of the crossbreeding system, the management system and the criteria of economic efficiency used in the production system (Wolfova et al, 2001). The fact that selection of parents in one type of mating system and environment may not optimize progeny performance in another type of system and environment, was described in the work of Weigel et al (2001) or Mulder and Bijma (2005).…”