Effects of pasture fertilization on the content of plasma minerals in grazing cows, 2: Yearly changes in plasma mineral levels in relation to the improvement of fertilizer.
1991
Kushibiki S. | Umemura K. | Hayashi T.
The relationship between pasture fertilization and the plasma mineral levels of grazing cows was studied from 1882 to 1988. Until 1982, the pasture had been used for beef cow grazing with conventional fertilizer application (N: 171, P2O5: 111, K20: 171 kg/ha/year) for more than 10 years. Around 1982, symptoms hypomagnesemia and Grass Tetany were observed in the grazing cows. Then, after 1983, the pasture was fertilized with an improved set of N: 171, P2O5: 128, K2O: 42, MgO: 84, CaO: 117 kg/ha/year. In 1985, fertilization was further improved as follows; N: 171 to 120, P2O5: 128 to 90 kg/ha/year, along with the application of Dolomite and in 1984 and 1987. 171 Japanese Black Cows (134 lactating cows and 37 nonlactating cows) were grazed on the pasture from April to November for 7 years. All the pregnant cows calved in March, and their calves were weaned in October every year. Live body weight of all the cows was determined on intervals of two weeks. Blood samples were taken from 70 cows during the grazing period in 1982, 1984, 1987 and 1988.
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