Keywords: Nutrient requirement of dairy cattle, N fertiliser, Herd fertility, Nutrient recycling, Trace elements, Geo-ecology.
The quantity parameters to be achieved in grassland production are set by the requirements of dairy cows for energy, protein, minerals and vitamins needed for maintenance and milk production. The paper describes these requirements and emphasises their dependence on the botanical composition of the sward, grassland management and application of fertilisers. Economical aspects of livestock production and grassland productivity are discussed as well as the consequences of excessive fertiliser use on animal health and environment. Instead of focusing on Mg and Na in grassland nutrition which are frequently in short supply for ruminants attention is primarily paid to the microelements. These can occur in sub- and supra-optimal concentrations, respectively, due to geo-ecological or anthropogenic causes.
Prof. Dr H Beringer, BÃƒÂ¼ntehof Agricultural Research Station, BÃƒÂ¼nteweg 8, D-3000 Hannover 7812, Germany.
25 pages, 8 figures, 13 tables, 26 references.