2Y Sasaki,Y Koketsu. Mortality, death interval, survivals, and herd factors for death in gilts and sows in commercial breeding herds [J]. J Anim Sci, 2008, 86(11):3159-3165.
3Gaughan J B, R D A, Cameron G M, Dryden, et al. Effect of se- lection for leanness on overall reproductive performance in large white sows[J]. Anim Sci, 1995,61: 561-564.
4Challinor C M, G Dams, B Edwards, et al. The effect of body con- dition of gilts at first mating on long-term sow production [C]. British Society of Animal Science, Winter Meeting, Scarborough, York. 1996: 144.
5Boyle L, Leonard F C, Lynch B, et al. Sow culling patterns and sow welfare [J] . Ir Vet J,1998,51: 354-357.