Use of nitrogen inputs in dairy cow grazing
1996
Delaby, L. | Peyraud, J.-L. | Delagarde, R. (Institut National de la Recherche Agronomique (INRA), Saint-Gilles (France). Station de Recherches sur la Vache Laitiere)
In the context of milk quotas, the availability of herbage areas, and environmental constraints, breeders have all interest to optimise the use of nitrogen input for grazing systems. The consequences of such options on the animals are analysed in the light of the studies conducted by the French Dairy Research Station of the INRA over several years, both in Normandy and Brittany. As a rule, the concomitant reduction of nitrogen fertilisation and stocking rates results in unchanged individual performances, lower yields per hectare, and a marked reduction of the nitrogen input from animal faeces. In areas with poor natural soil nitrogen supply the impact of a reduced nitrogen fertilisation on milk yields is the greater, the lower the protein content of the grass. Feed supplementation according to the animals' protein requirements allows this protein deficit to be corrected while maintaining biological performance. Nitrogen excretion is lower than on well fertilised pastures
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