Development of an animal model for across-herd genetic evaluation of number born alive in swine

Abstract

An animal model and computer software were developed to conduct across-herd genetic evaluations using data from producers participating in the Sow Productivity Index program of the American Yorkshire Club. The final data set consisted of 61,596 litter records from 1986 to early 1990. The animal model included fixed contemporary group effects and random additive direct, service sire, permanent environmental, and residual effects. Additive genetic relationships among animals were included. A separate relationship matrix for service sires and their sires was also included. A data set similar to the Yorkshire field data was simulated to use in testing the animal model. The simulated data set consisted of 40 herds, each with 120 reproducing dams and either four or five sires. Six generations of simulated data were produced, resulting in 20,605 litter records. These records were then evaluated using the animal model for number of pigs born alive. Finally, correlations between the true breeding values from the simulation and the predicted breeding values were computed. The correlation between the 918 true and predicted sire breeding values was considerably lower for the animal model without a service sire effect than when it was included (.53 vs .74, respectively). However, the difference was cut in half (.66 vs .77) when only sires with greater than five daughter records were included. The high accuracy of the animal model with a random service sire effect indicates that the proposed model adequately accounts for the variation found in records for number of pigs born alive.

Selection for litter size at day five to improve litter size at weaning and piglet survival rate1

“…This component is not related to the genotype of the piglet, but accounts for variation of sire permanent effects on sire fertility. The estimated variance components were consistent with reports in previous studies (e.g., See et al, 1993;Woodward et al, 1993;Van der Lende et al, 1999;Hamann et al, 2004). On the other hand, the variance component of sire genetic effects on litter size reflects sire fertility and the contribution to embryo survival through the offspring's genotype.…”

“…Litter size and piglet survival rate are usually treated as traits of the sow. However, the fertilization capacity of the service-sire and the genotype of the piglet could have an effect on these traits (Strang, 1970;Hill and Webb, 1982;See et al, 1993;Woodward et al, 1993;Van der Lende et al, 1999). It therefore seems reasonable to estimate genetic parameters for these traits based on a model that includes effects of sow and service-sire.…”

Biology and genetics of reproduction.

“…They have confirmed the prominent part of sow genotype, but have also shown that both progeny and boa r genotypes significantly influence litter traits. The service sire has a rather limited effect on litter size 0-5% of phenotypic variance) according to Ollivier and Legault 0967), See et al 0993), Beauvois et al 0997), but taking into account this effect has been shown to improve genetic evaluation models for litter size (Woodward et al , 1993;Beauvois, 1996). Similarly, low but non-negligible additive direct genetic effects on embryonic survival ( 4% of phenotypic variance) and litter weight at 21 days (6% of phenotypic variance) were obtained by Gama et al (1991) and Rodriguez et al 0994), respectively.…”

Effect of service sire on litter size traits in Czech Large White and Landrace pigs

“…When considering the relationship matrix, a joint matrix for sows and boars has generally been defined. In contrast to this most common procedure, Woodward et al (1993) constructed separate relationship matrices for sows and boars.…”