Estimation of genetic parameters for body weight of the Goettingen minipig with random regression models

F. Köhn ^1*, A. R. Sharifi ¹, . Malovrh ², H. Simianer ¹

¹ Institute of Animal Breeding and Genetics, University of Göttingen, 37075 Göttingen, Germany
² Animal Science Dept., Biotechnical Faculty, University of Ljubljana, 1230 Domale, Slovenia

^* To whom correspondence should be addressed. E-mail: fkoehn{at}gwdg.de.

	Abstract

The Goettingen minipig is a laboratory animal especially developed for medical research. For easy and comfortable handling during experiments, and to minimize costs, a low body weight is essential. To breed for an even smaller minipig, genetic parameters for body weight were estimated using a random regression model (RRM). The RRM was calculated using random animal, common litter environment and permanent environment effects, respectively. Regressions for the random effects in the RRM were modeled using Legendre polynomials from second to fourth order of fit in different combinations. The model was applied to a data set which focused on the time period from 30 to 400 d of age. Eight age classes were built to consider heterogeneous residual variances. The heritabilities were moderate and ranged from 0.211 (375 d of age) to 0.2542 (275 d of age). The variances initially decreased and then increased towards the end of the examined time period for permanent environment and litter effect. Genetic and phenotypic correlations between body weights in different age classes decreased with increasing distance between age classes. The major eigenfunction showed positive values throughout the whole trajectory, i.e. a selection for low body weight has positive effects on this trait throughout the whole range of time. On the basis of the estimated genetic parameters a breeding scheme can be created to develop genetically smaller Goettingen minipigs in the future.

Key Words: body weight, genetic parameters, Goettingen minipig, random regression