Die Selektion auf Wurfgröße beim Schwein
Abstract. Title ofthe paper: Selection for litter size in swine
The present paper deals with the estimation of genetic parameter for litter size of two purebred lines 03 and 04 in order to choose the optimal model for variance component estimation. Data from nucleus and multiplier farms from 1989 to 1997 of a North-German breeding Company were observed. 9,957 litter records from 3,423 sows of line 03 and 5,045 litter records from 2,009 sows of line 04 were collected. The 404 sires of line 03 had an average of 8.5 daughters and the 285 sires of line 04 had an average of 7,0 daughters. Litter size were different between both lines, 9.6 (3.2) and 10.1 (3.4) for line 03 and 04, respectively.
Genetic correlations between litters of parity 1, 2 and 3 were rg > 0,81 on high level. Also, in bivariate analysis high correlations rg > 0,88 were estimated for both lines. This model takes the matemal effect for the first parity and the permanent environment in subsequent parities into account. Due to the results a repeatability model may be appropiate for breeding values of litter size. Estimation of genotype by environment interaction showed different heritabilities between farms. Genetic corrlation was on moderate level (rg = 0,61) between two farms for line 04, other estimates ranged between rg = 0,73 and 0,97.
