BENEFIT OF MULTIPLE-TRAIT SELECTION TO INCREASE REPRODUCTIVE TRAITS -EXPERIMENTAL-EVIDENCE FROM GOLDEN-HAMSTERS

Fifteen generations of selection were conducted to study responses for litter size at birth (LSB), weight at weaning of standardized litter (LWW), and individual body weight at 8 wk of age (BW8) using golden ha msters as an experimental model for pigs. The experiment involved thre e lines: selection on an aggregate breeding value of LSB, LWW, and BW8 (line W); selection on an aggregate breeding value of LSB and LWW (li ne R); and a randomly selected control (line C). Selection in W and R was based on breeding values from a multiple trait animal model. Restr icted maximum likelihood with an animal model was used to estimate gen etic parameters and genetic trends. Heritability estimates for LSB, LW W, and BW8 were .10, .47, and .52, respectively, and genetic correlati ons between traits were all positive. The mean estimated breeding valu e (EBV) for LSB in generation 15 was +2.2 pups in W and R. The mean EB V for LWW in generation 15 was +318 g for W and +174 g for R, and for BW8 means were +64 g and +24 g, respectively. Average inbreeding at ge neration 16 was 13.4, 19.5, and 8.0% for W, R, and G, respectively. In cluding BW8 in the selection criterion reduced inbreeding and had a be neficial effect on selection responses in LSB, LWW, and BW8.