4[8]Lund. V, Algers. B. Research on animal health and welfare in organic farming-a literature review[J]. Livestock Production Science, 2003,80: 55- 68
5[9]Kouba. M. , Quality of organic animal products[J]. Livestock Production Science. 80 (2003) 33-40.
6[10]Bartussek. ,H. A review of the animal needs index (ANI) for the assessment of animals' well being in the housing systems for Austrian proprietary products and legislation[J]. Livestock Production Science, 1999,61:179- 192.
7Qian H. Adverse effects of wide calcium: Phosphorus rations on supplemental phytase efficacy for weanling pigs fed two dietary phosphorus leves. J. Anim. Sci., 1996,74:1288-1297.
8Cromwell G. L. Efficacy of recombinant-devived phytase in improving the bioavailability of phosphorus in corn-soybean meal diets for pigs. J.Anim. Sci., 1995,73 : 2000-2008.
9Gromwell G. L. Efficacy of phytase in improving the bioavailibity of phosphorus in soybean meal and corn-soybean meal diets for pigs. J. Anim. Sci., 1993,71 ; 1831- 1840.
10Cromwell G.L. Efficacy of low-activity microbial phytase in improving the bioavailability of phosphorus in corn-soybean meal diets for pigs.J.Anim. Sci., 1995,73:449-456.