科研之友
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摘要
Twenty five mix breed cattle between the ages of 6 months and 2 years with a mean body mass of 337 kg were randomly selected from a herd exclusively on communal grazing and receiving no supplements and were used to evaluate how animals were able to cope on communal grazing without supplements. Bone, faecal and blood samples were sampled once monthly for 12 months and pasture samples were collected from grazing. Faecal P was significantly (P<0.05) higher, (4.70 mg/g) in March 2006 compared to all other months and was significantly (P<0.05) lower (1.17 mg/g) in July 2006 than all other months. This reflects grass P which was significantly (P<0.05) higher (2.4 mg/g) in March 2006 compared with all other months and significantly (P<0.05) lower (0.33 mg/g) in July 2006 compared to all other months and the rainfall which was also higher (111.1 mm) in March 2006 and lower (0 mm) in July 2006. The results showed that animals were not able to maintain normal values of P, Ca and Mg, especially of blood P when dietary minerals were limiting. Animals were able to use homeostatic mechanisms to maintain bone Mg in the face of deficient concentrations of Mg in the grass.
- 出版日期2017-1
- 单位西北大学
