Roehe R,Kennedy B W.Effect of selection for maternal and direct effects on genetic improvement of litter size in swine[J].J Anim Sci,1993,71(11):2891-2904.
[3]
Roehe R,Kennedy B W.Estimation of genetic parameters for litter size in Yorkshire and Landrace swine with each parity of farrowing treated as a different trait[J].J Anim Sci,1995,73:2959-2970.
[4]
Haley C S,Avalos E,Smith C.Selection for litter size in the pig[J].Anim breed Abstr,1988,56:317-332.
Alfonso L,Noguera J L,Babot D,et al.Estimation of genetic parameters for litter size at different parities in pigs[J].Livestock Production Science,1997,47:149-156.