Soil nitrates in pastures rotationally grazed by cows: relation with urea in milk and blood plasma (original) (raw)

Abstract

An experiment was carried out to evaluate the effect of three management systems on animal performance and nitrogen (N) cycle in permanent pastures. The managements were an intensive system with a high N fertilizer application at 136 kg N ha-1 and a stocking rate of 3.35 cows ha-1 (H-N), a system with moderate N application with 91 kg N ha-1 year-1 and the same stocking rate (M-N) and a system without N fertilizer application and with 2.51 cows ha-1 (0-N). The individual milk production was not affected by treatments but the milk yield per hectare was largely influenced by the stocking rate. Milk and plasma urea concentrations were the highest in the H-N group and the lowest in the 0-N group. Similarly, the system N balance was the highest in H-N and the smallest in 0-N group. Inversely the N use efficiency was the highest in 0-N group. Soil nitrate concentration in 0-90 cm deep cores was higher in H-N than 0-N samples.

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