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Presenter Information

H Valk, ID-DLO
A M. van Vuuren, ID-DLO

Publication Date

1997

Location

Manitoba and Saskatchewan

Description

In four zero-grazing experiments, the effects ofN fertilizer (450 to 300 to 150 kg/ha/yr) on intake and utilization of some grass minerals (Ca, P and Mg), were investigated. Grass was offered ad lib to 12 cows per N treatment. A reduction in N fertilizer resulted in lower mean contents and intakes of Ca and Mg while P content and intake increased in late summer/autumn. The output of these minerals in milk and urine was relatively low. Therefore, a reduced intake of Ca and Mg resulted in a lower faecal output of these minerals. The ratio between intake and requirement varied for Ca between 141% and 210%, for P between 115% and 140% and for Mg between 73% and 97%. Nevertheless, no signs of hypomagnesemia were obtained at the lowest levels of Mg intake as a consequence of a reduction in N fertilizer.

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Mineral Intake and Utilization by Dairy Cows Offered Grass Fertilized with Different Levels of Nitrogen

Manitoba and Saskatchewan

In four zero-grazing experiments, the effects ofN fertilizer (450 to 300 to 150 kg/ha/yr) on intake and utilization of some grass minerals (Ca, P and Mg), were investigated. Grass was offered ad lib to 12 cows per N treatment. A reduction in N fertilizer resulted in lower mean contents and intakes of Ca and Mg while P content and intake increased in late summer/autumn. The output of these minerals in milk and urine was relatively low. Therefore, a reduced intake of Ca and Mg resulted in a lower faecal output of these minerals. The ratio between intake and requirement varied for Ca between 141% and 210%, for P between 115% and 140% and for Mg between 73% and 97%. Nevertheless, no signs of hypomagnesemia were obtained at the lowest levels of Mg intake as a consequence of a reduction in N fertilizer.